Publications by authors named "Laura B Martin"

52 Publications

Short Vi-polysaccharide abrogates T-independent immune response and hyporesponsiveness elicited by long Vi-CRM conjugate vaccine.

Proc Natl Acad Sci U S A 2020 09 8;117(39):24443-24449. Epub 2020 Sep 8.

Technology Platform Unit, GSK Vaccines Institute for Global Health (GVGH), 53100 Siena, Italy.

Polysaccharide-protein conjugates have been developed to overcome the T-independent response, hyporesponsiveness to repeated vaccination, and poor immunogenicity in infants of polysaccharides. To address the impact of polysaccharide length, typhoid conjugates made with short- and long-chain fractions of Vi polysaccharide with average sizes of 9.5, 22.8, 42.7, 82.0, and 165 kDa were compared. Long-chain-conjugated Vi (165 kDa) induced a response in both wild-type and T cell-deficient mice, suggesting that it maintains a T-independent response. In marked contrast, short-chain Vi (9.5 to 42.7 kDa) conjugates induced a response in wild-type mice but not in T cell-deficient mice, suggesting that the response is dependent on T cell help. Mechanistically, this was explained in neonatal mice, in which long-chain, but not short-chain, Vi conjugate induced late apoptosis of Vi-specific B cells in spleen and early depletion of Vi-specific B cells in bone marrow, resulting in hyporesponsiveness and lack of long-term persistence of Vi-specific IgG in serum and IgG antibody-secreting cells in bone marrow. We conclude that while conjugation of long-chain Vi generates T-dependent antigens, the conjugates also retain T-independent properties, leading to detrimental effects on immune responses. The data reported here may explain some inconsistencies observed in clinical trials and help guide the design of effective conjugate vaccines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.2005857117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7533886PMC
September 2020

Booster Vaccination With GVGH 1790GAHB GMMA Vaccine Compared to Single Vaccination in Unvaccinated Healthy European Adults: Results From a Phase 1 Clinical Trial.

Front Immunol 2019 8;10:335. Epub 2019 Mar 8.

GSK Vaccines Institute for Global Health, Siena, Italy.

The investigational vaccine (1790GAHB) based on GMMA (generalized modules for membrane antigens) is immunogenic, with an acceptable safety profile in adults. However, pre-vaccination anti- lipopolysaccharide (LPS) antibody levels seemed to impact vaccine-related immune responses. This phase 1, open-label, non-randomized extension study (ClinicalTrials.gov: NCT03089879) evaluated immunogenicity of a 1790GAHB booster dose in seven adults with undetectable antibodies prior to priming with three 1790GAHB vaccinations 2-3 years earlier (boosted group), compared to one dose in 28 vaccine-naïve individuals (vaccine-naïve group). Anti- LPS serum IgG geometric mean concentrations and seroresponse (increase of ≥25 EU or ≥50% from baseline antibody ≤ 50 EU and ≥50 EU, respectively) rates were calculated at vaccination (day [D]1), D8, D15, D29, D85. Safety was assessed. Geometric mean concentrations at D8 were 168 EU (boosted group) and 32 EU (vaccine-naïve group). Response peaked at D15 (883 EU) and D29 (100 EU) for the boosted and vaccine-naïve groups. Seroresponse rates at D8 were 86% (boosted group) and 24% (vaccine-naïve group) and increased at subsequent time points. Across both groups, pain (local) and fatigue (systemic) were the most frequent solicited adverse events (AEs). Unsolicited AEs were reported by 57% of boosted and 25% of vaccine-naïve participants. No deaths, serious AEs, or AEs of special interest (except one mild neutropenia case, possibly vaccination-related) were reported. One 1790GAHB dose induced a significant booster response in previously-primed adults, regardless of priming dose, and strong immune response in vaccine-naïve individuals. Vaccination was well tolerated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fimmu.2019.00335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418009PMC
September 2020

A Phase 2a Randomized Study to Evaluate the Safety and Immunogenicity of the 1790GAHB Generalized Modules for Membrane Antigen Vaccine against Administered Intramuscularly to Adults from a Shigellosis-Endemic Country.

Front Immunol 2017 22;8:1884. Epub 2017 Dec 22.

GSK Vaccines Institute for Global Health, Siena, Italy.

Shigellosis is a mild-to-severe diarrheal infection, caused by the genus , and is responsible for significant morbidity and mortality worldwide. We evaluated the safety and immunogenicity of an investigational vaccine (1790GAHB) based on generalized modules for membrane antigens (GMMA) in Kenya, a -endemic country. This phase 2a, observer-blind, controlled randomized study (NCT02676895) enrolled 74 healthy adults aged 18-45 years, of whom 72 were vaccinated. Participants received, in a 1:1:1 ratio, two vaccinations with the 1790GAHB vaccine at doses of either 1.5/25 μg of O antigen (OAg)/protein (group 1.5/25 μg) or 5.9/100 μg (group 5.9/100 μg) at day (D) 1 and D29, or vaccination with a quadrivalent meningococcal vaccine at D1 and tetanus, diphtheria, and acellular pertussis vaccine at D29 (control group). Solicited and unsolicited adverse events (AEs), serious AEs (SAEs), and AEs of special interest (neutropenia and reactive arthritis) were collected. Anti- lipopolysaccharide (LPS) serum immunoglobulin G (IgG) geometric mean concentrations (GMC) were evaluated at D1, D29, and D57 and compared to anti- LPS antibody levels in convalescent patients naturally exposed to . The percentages of participants with seroresponse were also calculated. The most frequently reported solicited local and systemic AEs across all groups were pain and headache, respectively. Only one case of severe systemic reaction was reported (severe headache after first vaccination in group 5.9/100 μg). Seven and three episodes of neutropenia, assessed as probably or possibly related to vaccination respectively, were reported in the investigational and control groups, respectively. No other SAEs were reported. Despite very high baseline anti- LPS serum IgG levels, the 1790GAHB vaccine induced robust antibody responses. At D29, GMC increased 2.10- and 4.43-fold from baseline in groups 1.5/25 and 5.9/100 μg, respectively, whereas no increase was observed in the control group. Antibody titers at D57 were not statistically different from those at D29. Seroresponse was 68% at D29 and 90% at D57 in group 1.5/25 μg, and 96% after each vaccination in group 5.9/100 μg. The 1790GAHB vaccine was well tolerated and highly immunogenic in a population of African adults, regardless of the GMMA OAg/protein content used.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fimmu.2017.01884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5763125PMC
December 2017

Safety Profile and Immunologic Responses of a Novel Vaccine Against Shigella sonnei Administered Intramuscularly, Intradermally and Intranasally: Results From Two Parallel Randomized Phase 1 Clinical Studies in Healthy Adult Volunteers in Europe.

EBioMedicine 2017 Aug 15;22:164-172. Epub 2017 Jul 15.

GSK Vaccines Institute for Global Health, Siena, Italy. Electronic address:

Background: Approximately 164,000 deaths yearly are due to shigellosis, primarily in developing countries. Thus, a safe and affordable Shigella vaccine is an important public health priority. The GSK Vaccines Institute for Global Health (GVGH) developed a candidate Shigella sonnei vaccine (1790GAHB) using the Generalized Modules for Membrane Antigens (GMMA) technology. The paper reports results of 1790GAHB Phase 1 studies in healthy European adults.

Methods: To evaluate the safety and immunogenicity profiles of 1790GAHB, we performed two parallel, phase 1, observer-blind, randomized, placebo-controlled, dose escalation studies in France ("study 1") and the United Kingdom ("study 2") between February 2014 and April 2015 (ClinicalTrials.gov, number NCT02017899 and NCT02034500, respectively) in 18-45years old subjects (50 in study 1, 52 in study 2). Increasing doses of Alhydrogel adsorbed 1790, expressed by both O Antigen (OAg) and protein quantity, or placebo were given either by intramuscular route (0.059/1, 0.29/5, 1.5/25, 2.9/50, 5.9/100μg of OAg/μg of protein; study 1) or by intradermal (ID), intranasal (IN) or intramuscular (IM) route of immunization (0.0059/0.1, 0.059/1, 0.59/10μg ID, 0.29/5, 1.2/20, 4.8/80μg IN and 0.29/5μg IM, respectively; study 2). In absence of serologic correlates of protection for Shigella sonnei, vaccine induced immunogenicity was compared to anti-LPS antibody in a population naturally exposed to S. sonnei.

Findings: Vaccines were well tolerated in both studies and no death or vaccine related serious adverse events were reported. In study 1, doses ≥1.5/25μg elicited serum IgG median antibody greater than median level in convalescent subjects after the first dose. No vaccine group in study 2 achieved median antibody greater than the median convalescent antibody.

Interpretation: Intramuscularly administered Shigella sonnei GMMA vaccine is well tolerated, up to and including 5.9/100μg and induces antibody to the OAg of at least the same magnitude of those observed following natural exposure to the pathogen. Vaccine administered by ID or IN, although well tolerated, is poorly immunogenic at the doses delivered. The data support the use of the GMMA technology for the development of intramuscular multivalent Shigella vaccines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ebiom.2017.07.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552227PMC
August 2017

An evaluation of purified Salmonella Typhi protein antigens for the serological diagnosis of acute typhoid fever.

J Infect 2017 08 25;75(2):104-114. Epub 2017 May 25.

The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Viet Nam; Centre for Tropical Medicine and Global Health, Oxford University, Oxford, United Kingdom; The Department of Medicine, University of Cambridge, Cambridge, United Kingdom. Electronic address:

Objectives: The diagnosis of typhoid fever is a challenge. Aiming to develop a typhoid diagnostic we measured antibody responses against Salmonella Typhi (S. Typhi) protein antigens and the Vi polysaccharide in a cohort of Bangladeshi febrile patients.

Methods: IgM against 12 purified antigens and the Vi polysaccharide was measured by ELISA in plasma from patients with confirmed typhoid fever (n = 32), other confirmed infections (n = 17), and healthy controls (n = 40). ELISAs with the most specific antigens were performed on plasma from 243 patients with undiagnosed febrile disease.

Results: IgM against the S. Typhi protein antigens correlated with each other (rho > 0.8), but not against Vi (rho < 0.6). Typhoid patients exhibited higher IgM against 11/12 protein antigens and Vi than healthy controls and those with other infections. Vi, PilL, and CdtB exhibited the greatest sensitivity and specificity. Specificity and sensitivity was improved when Vi was combined with a protein antigen, generating sensitivities and specificities of 0.80 and >0.85, respectively. Applying a dynamic cut-off to patients with undiagnosed febrile disease suggested that 34-58% had an IgM response indicative of typhoid.

Conclusions: We evaluated the diagnostic potential of several S. Typhi antigens; our assays give good sensitivity and specificity, but require further assessment in differing patient populations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jinf.2017.05.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5522525PMC
August 2017

Evaluation of the Clinical and Microbiological Response to Salmonella Paratyphi A Infection in the First Paratyphoid Human Challenge Model.

Clin Infect Dis 2017 04;64(8):1066-1073

Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford, UK.

Background: To expedite the evaluation of vaccines against paratyphoid fever, we aimed to develop the first human challenge model of Salmonella enterica serovar Paratyphi A infection.

Methods: Two groups of 20 participants underwent oral challenge with S. Paratyphi A following sodium bicarbonate pretreatment at 1 of 2 dose levels (group 1: 1-5 × 103 colony-forming units [CFU] and group 2: 0.5-1 × 103 CFU). Participants were monitored in an outpatient setting with daily clinical review and collection of blood and stool cultures. Antibiotic treatment was started when prespecified diagnostic criteria were met (temperature ≥38°C for ≥12 hours and/or bacteremia) or at day 14 postchallenge.

Results: The primary study objective was achieved following challenge with 1-5 × 103 CFU (group 1), which resulted in an attack rate of 12 of 20 (60%). Compared with typhoid challenge, paratyphoid was notable for high rates of subclinical bacteremia (at this dose, 11/20 [55%]). Despite limited symptoms, bacteremia persisted for up to 96 hours after antibiotic treatment (median duration of bacteremia, 53 hours [interquartile range, 24-85 hours]). Shedding of S. Paratyphi A in stool typically preceded onset of bacteremia.

Conclusions: Challenge with S. Paratyphi A at a dose of 1-5 × 103 CFU was well tolerated and associated with an acceptable safety profile. The frequency and persistence of bacteremia in the absence of clinical symptoms was notable, and markedly different from that seen in previous typhoid challenge studies. We conclude that the paratyphoid challenge model is suitable for the assessment of vaccine efficacy using endpoints that include bacteremia and/or symptomatology.

Clinical Trials Registration: NCT02100397.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/cid/cix042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5439345PMC
April 2017

Status of paratyphoid fever vaccine research and development.

Vaccine 2016 06 12;34(26):2900-2902. Epub 2016 Apr 12.

Center of Excellence for Women and Child Health, The Aga Khan University, Stadium Road, Karachi 74800, Pakistan. Electronic address:

Salmonella enterica serovars Typhi and Paratyphi (S. Paratyphi) A and B cause enteric fever in humans. Of the paratyphoid group, S. Paratyphi A is the most common serovar. In 2000, there were an estimated 5.4 million cases of S. Paratyphi A worldwide. More recently paratyphoid fever has accounted for an increasing fraction of all cases of enteric fever. Although vaccines for typhoid fever have been developed and in use for decades, vaccines for paratyphoid fever have not yet been licensed. Several S. Paratyphi A vaccines, however, are in development and based on either whole cell live-attenuated strains or repeating units of the lipopolysaccharide O-antigen (O:2) conjugated to different protein carriers. An O-specific polysaccharide (O:2) of S. Paratyphi A conjugated to tetanus toxoid (O:2-TT), for example, has been determined to be safe and immunogenic after one dose in Phase I and Phase II trials. Two other conjugated vaccine candidates linked to diphtheria toxin and a live-attenuated oral vaccine candidate are currently in preclinical development. As promising vaccine candidates are advanced along the development pipeline, an adequate supply of vaccines will need to be ensured to meet growing demand, particularly in the most affected countries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2016.03.106DOI Listing
June 2016

Nontyphoidal salmonella disease: Current status of vaccine research and development.

Vaccine 2016 06 29;34(26):2907-2910. Epub 2016 Mar 29.

Center of Excellence in Woman and Child Health, The Aga Khan University, Stadium Road Karachi 74800, Pakistan. Electronic address:

Among more than 2500 nontyphoidal Salmonella enterica (NTS) serovars, S. enterica serovar Typhimurium and S. enterica serovar Enteritidis account for approximately fifty percent of all human isolates of NTS reported globally. The global incidence of NTS gastroenteritis in 2010 was estimated to be 93 million cases, approximately 80 million of which were contracted via food-borne transmission. It is estimated that 155,000 deaths resulted from NTS in 2010. NTS also causes severe, extra-intestinal, invasive bacteremia, referred to as invasive nontyphoidal Salmonella (iNTS) disease. iNTS disease usually presents as a febrile illness, frequently without gastrointestinal symptoms, in both adults and children. Symptoms of iNTS are similar to malaria, often including fever (>90%) and splenomegaly (>40%). The underlying reasons for the high rates of iNTS disease in Africa are still being elucidated. Evidence from animal and human studies supports the feasibility of developing a safe and effective vaccine against iNTS. Both antibodies and complement can kill Salmonella species in vitro. Proof-of-principle studies in animal models have demonstrated efficacy for live attenuated and subunit vaccines that target the O-antigens, flagellin proteins, and other outer membrane proteins of serovars Typhimurium and Enteritidis. More recently, a novel delivery strategy for NTS vaccines has been developed: the Generalized Modules for Membrane Antigens (GMMA) technology which presents surface polysaccharides and outer membrane proteins in their native conformation. GMMA technology is self-adjuvanting, as it delivers multiple pathogen-associated molecular pattern molecules. GMMA may be particularly relevant for low- and middle-income countries as it has the potential for high immunologic potency at a low cost and involves a relatively simple production process without the need for complex conjugation. Several vaccines for the predominant NTS serovars Typhimurium and Enteritidis, are currently under development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2016.03.072DOI Listing
June 2016

The transfer and decay of maternal antibody against Shigella sonnei in a longitudinal cohort of Vietnamese infants.

Vaccine 2016 Feb 29;34(6):783-90. Epub 2015 Dec 29.

Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Viet Nam; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, Oxford, UK; London School of Hygiene and Tropical Medicine, London, UK. Electronic address:

Background: Shigella sonnei is an emergent and major diarrheal pathogen for which there is currently no vaccine. We aimed to quantify duration of maternal antibody against S. sonnei and investigate transplacental IgG transfer in a birth cohort in southern Vietnam.

Methods And Results: Over 500-paired maternal/infant plasma samples were evaluated for presence of anti-S. sonnei-O IgG and IgM. Longitudinal plasma samples allowed for the estimation of the median half-life of maternal anti-S. sonnei-O IgG, which was 43 days (95% confidence interval: 41-45 days). Additionally, half of infants lacked a detectable titer by 19 weeks of age. Lower cord titers were associated with greater increases in S. sonnei IgG over the first year of life, and the incidence of S. sonnei seroconversion was estimated to be 4/100 infant years. Maternal IgG titer, the ratio of antibody transfer, the season of birth and gestational age were significantly associated with cord titer.

Conclusions: Maternal anti-S. sonnei-O IgG is efficiently transferred across the placenta and anti-S. sonnei-O maternal IgG declines rapidly after birth and is undetectable after 5 months in the majority of children. Preterm neonates and children born to mothers with low IgG titers have lower cord titers and therefore may be at greater risk of seroconversion in infancy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2015.12.047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4742520PMC
February 2016

Joseph's Story: A Case Study of Late-Onset Necrotizing Enterocolitis From Early Birth to Recovery.

J Perinat Neonatal Nurs 2015 Oct-Dec;29(4):345-55

College of Nursing, The University of Arizona, Tucson, Arizona (Drs Gephart, Ms Kijewski, and Mr Johnson); and Graham's Foundation, Waterville, OH (Ms Martin).

Although necrotizing enterocolitis (NEC) is often catastrophic among premature infants, most cases occur in the first month after birth. This case study presents Joseph's story about a 24-week surviving twin who developed severe NEC at 5 months of age just days before he was to go home. The purpose of this case study report is to place Joseph and his parents' experience in the context of what is known about NEC risk factors, clinical presentation, and treatment, and then to offer recommendations to healthcare professionals to support families from NEC diagnosis to recovery. Now 5 years old, Joseph continues to manage consequences of NEC including deafness, developmental delay, multiple food allergies, and recurrent gastrointestinal challenges from short gut syndrome. Although NEC struck late and kept Joseph in the neonatal intensive care unit for 228 days, its consequences remain with this resilient child and his family.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/JPN.0000000000000137DOI Listing
December 2016

Production of a Shigella sonnei Vaccine Based on Generalized Modules for Membrane Antigens (GMMA), 1790GAHB.

PLoS One 2015 6;10(8):e0134478. Epub 2015 Aug 6.

Sclavo Behring Vaccines Institute for Global Health S.r.l., Siena, Italy.

Recently, we developed a high yield production process for outer membrane particles from genetically modified bacteria, called Generalized Modules of Membrane Antigens (GMMA), and the corresponding simple two step filtration purification, enabling economic manufacture of these particles for use as vaccines. Using a Shigella sonnei strain that was genetically modified to produce penta-acylated lipopolysaccharide (LPS) with reduced endotoxicity and to maintain the virulence plasmid encoding for the immunodominant O antigen component of the LPS, scale up of the process to GMP pilot scale was straightforward and gave high yields of GMMA with required purity and consistent results. GMMA were formulated with Alhydrogel and were highly immunogenic in mice and rabbits. In mice, a single immunization containing 29 ng protein and 1.75 ng of O antigen elicited substantial anti-LPS antibody levels. As GMMA contain LPS and lipoproteins, assessing potential reactogenicity was a key aspect of vaccine development. In an in vitro monocyte activation test, GMMA from the production strain showed a 600-fold lower stimulatory activity than GMMA with unmodified LPS. Two in vivo tests confirmed the low potential for reactogenicity. We established a modified rabbit pyrogenicity test based on the European Pharmacopoeia pyrogens method but using intramuscular administration of the full human dose (100 μg of protein). The vaccine elicited an average temperature rise of 0.5°C within four hours after administration, which was considered acceptable and showed that the test is able to detect a pyrogenic response. Furthermore, a repeat dose toxicology study in rabbits using intramuscular (100 μg/dose), intranasal (80 μg/dose), and intradermal (10 μg/dose) administration routes showed good tolerability of the vaccine by all routes and supported its suitability for use in humans. The S. sonnei GMMA vaccine is now in Phase 1 dose-escalation clinical trials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134478PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4527750PMC
May 2016

Understanding paratyphoid infection: study protocol for the development of a human model of Salmonella enterica serovar Paratyphi A challenge in healthy adult volunteers.

BMJ Open 2015 Jun 16;5(6):e007481. Epub 2015 Jun 16.

Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK Primary Care Clinical Trials Unit, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, Oxfordshire, UK.

Introduction: This study will develop the first human challenge model of paratyphoid infection which may then be taken forward to evaluate paratyphoid vaccine candidates. Salmonella Paratyphi A is believed to cause a quarter of the estimated 20 million cases of enteric fever annually. Epidemiological evidence also suggests that an increasing proportion of the enteric fever burden is attributable to S. Paratyphi infection meriting further attention and interest in vaccine development. Assessment of paratyphoid vaccine efficacy in preclinical studies is complicated by the lack of a small animal model and the human-restricted nature of the infection. The use of experimental human infection in healthy volunteers provides an opportunity to address these problems in a cost-effective manner.

Methods And Analysis: Volunteers will ingest virulent S. Paratyphi A bacteria (NVGH308 strain) with a bicarbonate buffer solution to establish the infectious dose resulting in an 'attack rate' of 60-75%. Using an a priori decision-making algorithm, the challenge dose will be escalated or de-escalated to achieve the target attack rate, with the aim of reaching the study end point while exposing as few individuals as possible to infection. The attack rate will be determined by the proportion of paratyphoid infection in groups of 20 healthy adult volunteers, with infection being defined by one or more positive blood cultures (microbiological end point) and/or fever, defined as an oral temperature exceeding 38 °C sustained for at least 12 h (clinical end point); 20-80 participants will be required. Challenge participants will start a 2-week course of an oral antibiotic on diagnosis of infection, or after 14 days follow-up.

Ethics And Dissemination: The strict eligibility criterion aims to minimise risk to participants and their close contacts. Ethical approval has been obtained. The results will be disseminated in a peer-reviewed journal and presented at international congresses.

Trial Registration Number: NCT02100397.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/bmjopen-2014-007481DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4480031PMC
June 2015

Typhoid fever in Fiji: a reversible plague?

Trop Med Int Health 2014 Oct 25;19(10):1284-92. Epub 2014 Jul 25.

Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, Oxford, UK.

The country of Fiji, with a population of approximately 870 000 people, faces a growing burden of several communicable diseases including the bacterial infection typhoid fever. Surveillance data suggest that typhoid has become increasingly common in rural areas of Fiji and is more frequent amongst young adults. Transmission of the organisms that cause typhoid is facilitated by faecal contamination of food or water and may be influenced by local behavioural practices in Fiji. The Fijian Ministry of Health, with support from Australian Aid, hosted a meeting in August 2012 to develop comprehensive control and prevention strategies for typhoid fever in Fiji. International and local specialists were invited to share relevant data and discuss typhoid control options. The resultant recommendations focused on generating a clearer sense of the epidemiology of typhoid in Fiji and exploring the contribution of potential transmission pathways. Additionally, the panel suggested steps such as ensuring that recommended ciprofloxacin doses are appropriate to reduce the potential for relapse and reinfection in clinical cases, encouraging proper hand hygiene of food and drink handlers, working with water and sanitation agencies to review current sanitation practices and considering a vaccination policy targeting epidemiologically relevant populations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/tmi.12367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4285329PMC
October 2014

Vaccines against invasive Salmonella disease: current status and future directions.

Hum Vaccin Immunother 2014 7;10(6):1478-93. Epub 2014 May 7.

Novartis Vaccines Institute for Global Health; Siena, Italy.

Though primarily enteric pathogens, Salmonellae are responsible for a considerable yet under-appreciated global burden of invasive disease. In South and South-East Asia, this manifests as enteric fever caused by serovars Typhi and Paratyphi A. In sub-Saharan Africa, a similar disease burden results from invasive nontyphoidal Salmonellae, principally serovars Typhimurium and Enteritidis. The existing Ty21a live-attenuated and Vi capsular polysaccharide vaccines target S. Typhi and are not effective in young children where the burden of invasive Salmonella disease is highest. After years of lack of investment in new Salmonella vaccines, recent times have seen increased interest in the area led by emerging-market manufacturers, global health vaccine institutes and academic partners. New glycoconjugate vaccines against S. Typhi are becoming available with similar vaccines against other invasive serovars in development. With other new vaccines under investigation, including live-attenuated, protein-based and GMMA vaccines, now is an exciting time for the Salmonella vaccine field.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4161/hv.29054DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4185946PMC
June 2015

Immunogenicity and safety of the Vi-CRM197 conjugate vaccine against typhoid fever in adults, children, and infants in south and southeast Asia: results from two randomised, observer-blind, age de-escalation, phase 2 trials.

Lancet Infect Dis 2014 Feb 28;14(2):119-29. Epub 2013 Nov 28.

Novartis Vaccines Institute for Global Health, Siena, Italy. Electronic address:

Background: Typhoid vaccination is a public health priority in developing countries where young children are greatly affected by typhoid fever. Because present vaccines are not recommended for children younger than 2 years, the Novartis Vaccines Institute for Global Health developed a conjugate vaccine (Vi-CRM197) for infant immunisation. We aimed to assess the immunogenicity and safety of Vi-CRM197 in participants of various ages in endemic countries in south and southeast Asia.

Methods: We did two randomised, observer-blind, age de-escalation, phase 2 trials at two sites in Pakistan and India (study A), and at one site in the Philippines (study B), between March 2, 2011, and Aug 9, 2012. Adults aged 18-45 years, children aged 24-59 months, older infants aged 9-12 months, and infants aged 6-8 weeks were randomly assigned (1:1) with a computer-generated randomisation list (block size of four) to receive either 5 μg Vi-CRM197 or 25 μg Vi-polysaccharide vaccine (or 13-valent pneumococcal conjugate vaccine in children younger than 2 years). Both infant populations received Vi-CRM197 concomitantly with vaccines of the Expanded Programme on Immunization (EPI), according to WHO schedule. With the exception of designated study site personnel responsible for vaccine preparation, study investigators, those assessing outcomes, and data analysts were masked to treatment allocation. We specified no a-priori null hypothesis for the immunogenicity or safety objectives and all analyses were descriptive. Analyses were by modified intention-to-treat. These studies are registered with ClinicalTrials.gov, numbers NCT01229176 and NCT01437267.

Findings: 320 participants were enrolled and vaccinated in the two trials: 200 in study A (all age groups) and 120 in study B (children and infants only), of whom 317 (99%) were included in the modified intention-to-treat analysis. One dose of Vi-CRM197 significantly increased concentrations of anti-Vi antibody in adults (from 113 U/mL [95% CI 67-190] to 208 U/mL [117-369]), children (201 U/mL [138-294] to 368 U/mL [234-580]), and older infants (179 U/mL [129-250] to 249 U/mL [130-477]). However, in children and older infants, a second dose of conjugate vaccine had no incremental effect on antibody titres and, at all ages, concentrations of antibodies increased substantially 6 months after vaccination (from 55 U/mL [33-94] to 63 U/mL [35-114] in adults, from 23 U/mL [15-34] to 51 U/mL [34-76] in children, and from 21 U/mL [14-31] to 22 U/mL [14-33] in older infants). Immune response in infants aged 6-8 weeks was lower than that in older participants and, 6 months after third vaccination, antibody concentrations were significantly higher than pre-vaccination concentrations in Filipino (21 U/mL [16-28] vs 2.88 U/mL [1.95-4.25]), but not Pakistani (3.76 U/mL [2.77-5.08] vs 2.77 U/mL [2.1-3.66]), infants. Vi-CRM197 was safe and well tolerated and did not induce any significant interference with EPI vaccines. No deaths or vaccine-related serious adverse events were reported throughout the studies.

Interpretation: Vi-CRM197 is safe and immunogenic in endemic populations of all ages. Given at 9 months of age, concomitantly with measles vaccine, Vi-CRM197 shows a promise for potential inclusion in EPI schedules of countries endemic for typhoid. An apparent absence of booster response and a reduction in antibody titres 6 months after immunisation should be further investigated, but data show that an immunogenic typhoid vaccine can be safely delivered to infants during EPI visits recommended by WHO.

Funding: Sclavo Vaccines Association and Regione Toscana.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/S1473-3099(13)70241-XDOI Listing
February 2014

Differential epidemiology of Salmonella Typhi and Paratyphi A in Kathmandu, Nepal: a matched case control investigation in a highly endemic enteric fever setting.

PLoS Negl Trop Dis 2013 22;7(8):e2391. Epub 2013 Aug 22.

Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal.

Background: Enteric fever, a systemic infection caused by the bacteria Salmonella Typhi and Salmonella Paratyphi A, is endemic in Kathmandu, Nepal. Previous work identified proximity to poor quality water sources as a community-level risk for infection. Here, we sought to examine individual-level risk factors related to hygiene and sanitation to improve our understanding of the epidemiology of enteric fever in this setting.

Methodology And Principal Findings: A matched case-control analysis was performed through enrollment of 103 blood culture positive enteric fever patients and 294 afebrile community-based age and gender-matched controls. A detailed questionnaire was administered to both cases and controls and the association between enteric fever infection and potential exposures were examined through conditional logistic regression. Several behavioral practices were identified as protective against infection with enteric fever, including water storage and hygienic habits. Additionally, we found that exposures related to poor water and socioeconomic status are more influential in the risk of infection with S. Typhi, whereas food consumption habits and migration play more of a role in risk of S. Paratyphi A infection.

Conclusions And Significance: Our work suggests that S. Typhi and S. Paratyphi A follow different routes of infection in this highly endemic setting and that sustained exposure to both serovars probably leads to the development of passive immunity. In the absence of a polyvalent vaccine against S. Typhi and S. Paratyphi A, we advocate better systems for water treatment and storage, improvements in the quality of street food, and vaccination with currently available S. Typhi vaccines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pntd.0002391DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3749961PMC
February 2014

Characterization of Citrobacter sp. line 328 as a source of Vi for a Vi-CRM(197) glycoconjugate vaccine against Salmonella Typhi.

J Infect Dev Ctries 2012 Nov 26;6(11):763-73. Epub 2012 Nov 26.

Novartis Vaccines Institute for Global Health.

Introduction: Salmonella enterica serovar Typhi is the causative agent of typhoid fever with over 22 million cases and over 200,000 deaths reported annually. A vaccine is much needed for use in young children and the Novartis Vaccines Institute for Global Health (NVGH) is developing a conjugate vaccine which targets S. Typhi Vi capsular polysaccharide.

Methodology: Here we describe a method suitable for industrial scale production of the Vi antigen based on expression by a Citrobacter line. We optimized the production of Vi by selecting a suitable Citrobacter strain (Citrobacter 328) that yields high and stable expression of Vi in chemically defined medium under industrial-scale fermentation conditions.

Results: Vi-CRM197 made using Vi from Citrobacter 328 elicited high anti-Vi antibody levels in mice and rabbits.

Conclusions: Citrobacter 328 is a suitable strain for production of Vi for conjugate anti-Typhi vaccines. Being a BSL-1 organism, which grows in defined medium and stably produces high yields of Vi, it offers excellent potential for safe production of inexpensive vaccines for populations at risk of typhoid fever.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3855/jidc.2495DOI Listing
November 2012

The capsular polysaccharide Vi from Salmonella typhi is a B1b antigen.

J Immunol 2012 Dec 16;189(12):5527-32. Epub 2012 Nov 16.

Medical Research Council Centre for Immune Regulation, School of Immunity and Infection, Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.

Vaccination with purified capsular polysaccharide Vi Ag from Salmonella typhi can protect against typhoid fever, although the mechanism for its efficacy is not clearly established. In this study, we have characterized the B cell response to this vaccine in wild-type and T cell-deficient mice. We show that immunization with typhoid Vi polysaccharide vaccine rapidly induces proliferation in B1b peritoneal cells, but not in B1a cells or marginal zone B cells. This induction of B1b proliferation is concomitant with the detection of splenic Vi-specific Ab-secreting cells and protective Ab in Rag1-deficient B1b cell chimeras generated by adoptive transfer-induced specific Ab after Vi immunization. Furthermore, Ab derived from peritoneal B cells is sufficient to confer protection against Salmonella that express Vi Ag. Expression of Vi by Salmonella during infection did not inhibit the development of early Ab responses to non-Vi Ags. Despite this, the protection conferred by immunization of mice with porin proteins from Salmonella, which induce Ab-mediated protection, was reduced postinfection with Vi-expressing Salmonella, although protection was not totally abrogated. This work therefore suggests that, in mice, B1b cells contribute to the protection induced by Vi Ag, and targeting non-Vi Ags as subunit vaccines may offer an attractive strategy to augment current Vi-based vaccine strategies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4049/jimmunol.1103166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3605773PMC
December 2012

O:2-CRM(197) conjugates against Salmonella Paratyphi A.

PLoS One 2012 7;7(11):e47039. Epub 2012 Nov 7.

Novartis Vaccines Institute for Global Health, Siena, Italy.

Enteric fevers remain a common and serious disease, affecting mainly children and adolescents in developing countries. Salmonella enterica serovar Typhi was believed to cause most enteric fever episodes, but several recent reports have shown an increasing incidence of S. Paratyphi A, encouraging the development of a bivalent vaccine to protect against both serovars, especially considering that at present there is no vaccine against S. Paratyphi A. The O-specific polysaccharide (O:2) of S. Paratyphi A is a protective antigen and clinical data have previously demonstrated the potential of using O:2 conjugate vaccines. Here we describe a new conjugation chemistry to link O:2 and the carrier protein CRM(197), using the terminus 3-deoxy-D-manno-octulosonic acid (KDO), thus leaving the O:2 chain unmodified. The new conjugates were tested in mice and compared with other O:2-antigen conjugates, synthesized adopting previously described methods that use CRM(197) as carrier protein. The newly developed conjugation chemistry yielded immunogenic conjugates with strong serum bactericidal activity against S. Paratyphi A.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0047039PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3492368PMC
April 2013

Phase 1 study in malaria naïve adults of BSAM2/Alhydrogel®+CPG 7909, a blood stage vaccine against P. falciparum malaria.

PLoS One 2012 4;7(10):e46094. Epub 2012 Oct 4.

Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIAID/NIH), Rockville, Maryland, United States of America.

Unlabelled: A Phase 1 dose escalating study was conducted in malaria naïve adults to assess the safety, reactogenicity, and immunogenicity of the blood stage malaria vaccine BSAM2/Alhydrogel®+ CPG 7909. BSAM2 is a combination of the FVO and 3D7 alleles of recombinant AMA1 and MSP1(42), with equal amounts by weight of each of the four proteins mixed, bound to Alhydrogel®, and administered with the adjuvant CPG 7909. Thirty (30) volunteers were enrolled in two dose groups, with 15 volunteers receiving up to three doses of 40 µg total protein at Days 0, 56, and 180, and 15 volunteers receiving up to three doses of 160 µg protein on the same schedule. Most related adverse events were mild or moderate, but 4 volunteers experienced severe systemic reactions and two were withdrawn from vaccinations due to adverse events. Geometric mean antibody levels after two vaccinations with the high dose formulation were 136 µg/ml for AMA1 and 78 µg/ml for MSP1(42). Antibody responses were not significantly different in the high dose versus low dose groups and did not further increase after third vaccination. In vitro growth inhibition was demonstrated and was closely correlated with anti-AMA1 antibody responses. A Phase 1b trial in malaria-exposed adults is being conducted.

Trial Registration: Clinicaltrials.gov NCT00889616.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0046094PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3464250PMC
April 2013

Vaccines for typhoid fever and other salmonelloses.

Authors:
Laura B Martin

Curr Opin Infect Dis 2012 Oct;25(5):489-99

Novartis Vaccines Institute for Global Health, Siena, Italy.

Purpose Of Review: This review summarizes the recent advances in vaccination against Salmonella enterica serovar Typhi and highlights the data supporting the development of next generation vaccines to address paratyphoid fever and invasive nontyphoidal Salmonella (iNTS) disease.

Recent Findings: There has been increasing awareness of the disease burden caused by S. Typhi particularly in Africa and greater recognition of S. Paratyphi A's contribution to enteric fever episodes throughout Asia. Groups have been working to improve the existing typhoid vaccines and provide comprehensive data on the feasibility of their implementation in endemic settings. These data have resulted in modifications to the recommendations for typhoid vaccination in traveller markets and endemic settings, and has also led to the development of S. Paratyphi A vaccine components that can be combined with existing typhoid vaccines to generate bivalent formulations against enteric fever. The epidemiology of iNTS serovars as cause of appreciable morbidity and mortality in Africa, and the need for vaccines, has also become more widely appreciated.

Summary: Current typhoid vaccines, although moderately effective for short periods of time, cannot be used in all age groups and only target one of the clinically relevant Salmonella serovars. Greater effort must be placed on the development and implementation of improved vaccines for the disease burden resulting from Typhi, Paratyphi A or iNTS infections.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/QCO.0b013e328356ffebDOI Listing
October 2012

Immunization with the conjugate vaccine Vi-CRM₁₉₇ against Salmonella typhi induces Vi-specific mucosal and systemic immune responses in mice.

Vaccine 2012 Sep 15;30(43):6111-4. Epub 2012 Jun 15.

Laboratorio di Microbiologia Molecolare e Biotecnologia, Dipartimento di Biotecnologie, Università di Siena, Italy.

Typhoid fever is a public health problem, especially among young children in developing countries. To address this need, a glycoconjugate vaccine Vi-CRM₁₉₇, composed of the polysaccharide antigen Vi covalently conjugated to the non-toxic mutant of diphtheria toxin CRM₁₉₇, is under development. Here, we assessed the antibody and cellular responses, both local and systemic, following subcutaneous injection of Vi-CRM₁₉₇. The glycoconjugate elicited Vi-specific serum IgG titers significantly higher than unconjugated Vi, with prevalence of IgG1 that persisted for at least 60 days after immunization. Vi-specific IgG, but not IgA, were present in intestinal washes. Lymphocytes proliferation after restimulation with Vi-CRM₁₉₇ was observed in spleen and mesenteric lymph nodes. These data confirm the immunogenicity of Vi-CRM₁₉₇ and demonstrate that the vaccine-specific antibody and cellular immune responses are present also in the intestinal tract, thus strengthening the suitability of Vi-CRM₁₉₇ as a promising candidate vaccine against Salmonella Typhi.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2012.05.081DOI Listing
September 2012

Immunogenicity of self-associated aggregates and chemically cross-linked conjugates of the 42 kDa Plasmodium falciparum merozoite surface protein-1.

PLoS One 2012 4;7(6):e36996. Epub 2012 Jun 4.

Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.

Self-associated protein aggregates or cross-linked protein conjugates are, in general, more immunogenic than oligomeric or monomeric forms. In particular, the immunogenicity in mice of a recombinant malaria transmission blocking vaccine candidate, the ookinete specific Plasmodium falciparum 25 kDa protein (Pfs25), was increased more than 1000-fold when evaluated as a chemical cross-linked protein-protein conjugate as compared to a formulated monomer. Whether alternative approaches using protein complexes improve the immunogenicity of other recombinant malaria vaccine candidates is worth assessing. In this work, the immunogenicity of the recombinant 42 kDa processed form of the P. falciparum merozoite surface protein 1 (MSP1(42)) was evaluated as a self-associated, non-covalent aggregate and as a chemical cross-linked protein-protein conjugate to ExoProtein A, which is a recombinant detoxified form of Pseudomonas aeruginosa exotoxin A. MSP1(42) conjugates were prepared and characterized biochemically and biophysically to determine their molar mass in solution and stoichiometry, when relevant. The immunogenicity of the MSP1(42) self-associated aggregates, cross-linked chemical conjugates and monomers were compared in BALB/c mice after adsorption to aluminum hydroxide adjuvant, and in one instance in association with the TLR9 agonist CPG7909 with an aluminum hydroxide formulation. Antibody titers were assessed by ELISA. Unlike observations made for Pfs25, no significant enhancement in MSP1(42) specific antibody titers was observed for any conjugate as compared to the formulated monomer or dimer, except for the addition of the TLR9 agonist CPG7909. Clearly, enhancing the immunogenicity of a recombinant protein vaccine candidate by the formation of protein complexes must be established on an empirical basis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0036996PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3366955PMC
October 2012

Efficient extraction of vaccines formulated in aluminum hydroxide gel by including surfactants in the extraction buffer.

Vaccine 2012 Jan 19;30(2):189-94. Epub 2011 Nov 19.

Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.

Efficient antigen extraction from vaccines formulated on aluminum hydroxide gels is a critical step for the evaluation of the quality of vaccines following formulation. It has been shown in our laboratory that the efficiency of antigen extraction from vaccines formulated on Alhydrogel decreased significantly with increased storage time. To increase antigen extraction efficiency, the present study determined the effect of surfactants on antigen recovery from vaccine formulations. The Plasmodium falciparum apical membrane antigen 1 (AMA1) formulated on Alhydrogel and stored at 2-8°C for 3 years was used as a model in this study. The AMA1 on Alhydrogel was extracted in the presence or absence of 30 mM sodium dodecyl sulfate (SDS) or 20mM cetylpyridinium chloride in the extraction buffer (0.60 M citrate, 0.55 M phosphate, pH 8.5) using our standard antigen extraction protocols. Extracted AMA1 antigen was analyzed by 4-20% Tris-glycine SDS-PAGE followed by silver staining or western blotting. The results showed that inclusion of SDS or cetylpyridinium chloride in extraction buffer increased the antigen recovery dramatically and can be used for efficient characterization of Alhydrogel vaccines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2011.11.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3246088PMC
January 2012

Safety, immunogenicity and dose ranging of a new Vi-CRM₁₉₇ conjugate vaccine against typhoid fever: randomized clinical testing in healthy adults.

PLoS One 2011 30;6(9):e25398. Epub 2011 Sep 30.

Center for the Evaluation of Vaccination, Vaccine & Infectious Disease Institute, University of Antwerp, Antwerp, Belgium.

Background: Typhoid fever causes more than 21 million cases of disease and 200,000 deaths yearly worldwide, with more than 90% of the disease burden being reported from Asia. Epidemiological data show high disease incidence in young children and suggest that immunization programs should target children below two years of age: this is not possible with available vaccines. The Novartis Vaccines Institute for Global Health developed a conjugate vaccine (Vi-CRM₁₉₇) for infant vaccination concomitantly with EPI vaccines, either starting at 6 weeks with DTP or at 9 months with measles vaccine. We report the results from a Phase 1 and a Phase 2 dose ranging trial with Vi-CRM₁₉₇ in European adults.

Methodology: Following randomized blinded comparison of single vaccination with either Vi-CRM₁₉₇ or licensed polysaccharide vaccines (both containing 25·0 µg of Vi antigen), a randomised observer blinded dose ranging trial was performed in the same center to compare three concentrations of Vi-CRM₁₉₇ (1·25 µg, 5·0 µg and 12·5 µg of Vi antigen) with the polysaccharide vaccine.

Principal Findings: All vaccines were well tolerated. Compared to the polysaccharide vaccine, Vi-CRM₁₉₇ induced a higher incidence of mild to moderate short lasting local pain. All Vi-CRM₁₉₇ formulations induced higher Vi antibody levels compared to licensed control, with clear dose response relationship.

Conclusions: Vi-CRM₁₉₇ did not elicit safety concerns, was highly immunogenic and is therefore suitable for further clinical testing in endemic populations of South Asia.

Trial Registration: ClinicalTrials.gov NCT01123941 NCT01193907.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0025398PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3184126PMC
January 2012

Impact on malaria parasite multiplication rates in infected volunteers of the protein-in-adjuvant vaccine AMA1-C1/Alhydrogel+CPG 7909.

PLoS One 2011 22;6(7):e22271. Epub 2011 Jul 22.

Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, University of Oxford, Oxford, United Kingdom.

Background: Inhibition of parasite growth is a major objective of blood-stage malaria vaccines. The in vitro assay of parasite growth inhibitory activity (GIA) is widely used as a surrogate marker for malaria vaccine efficacy in the down-selection of candidate blood-stage vaccines. Here we report the first study to examine the relationship between in vivo Plasmodium falciparum growth rates and in vitro GIA in humans experimentally infected with blood-stage malaria.

Methods: In this phase I/IIa open-label clinical trial five healthy malaria-naive volunteers were immunised with AMA1/C1-Alhydrogel+CPG 7909, and together with three unvaccinated controls were challenged by intravenous inoculation of P. falciparum infected erythrocytes.

Results: A significant correlation was observed between parasite multiplication rate in 48 hours (PMR) and both vaccine-induced growth-inhibitory activity (Pearson r = -0.93 [95% CI: -1.0, -0.27] P = 0.02) and AMA1 antibody titres in the vaccine group (Pearson r = -0.93 [95% CI: -0.99, -0.25] P = 0.02). However immunisation failed to reduce overall mean PMR in the vaccine group in comparison to the controls (vaccinee 16 fold [95% CI: 12, 22], control 17 fold [CI: 0, 65] P = 0.70). Therefore no impact on pre-patent period was observed (vaccine group median 8.5 days [range 7.5-9], control group median 9 days [range 7-9]).

Conclusions: Despite the first observation in human experimental malaria infection of a significant association between vaccine-induced in vitro growth inhibitory activity and in vivo parasite multiplication rate, this did not translate into any observable clinically relevant vaccine effect in this small group of volunteers.

Trial Registration: ClinicalTrials.gov [NCT00984763].
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022271PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3142129PMC
December 2011

Long term stability of a recombinant Plasmodium falciparum AMA1 malaria vaccine adjuvanted with Montanide(®) ISA 720 and stabilized with glycine.

Vaccine 2011 May 8;29(20):3640-5. Epub 2011 Apr 8.

Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Disease, National Institutes of Health, 5640 Fishers Lane, Rockville, MD 20852, USA.

Plasmodium falciparum apical membrane antigen 1 (AMA1) is an asexual blood-stage vaccine candidate against the malaria parasite. AMA1-C1/ISA 720 refers to a mixture of recombinant AMA1 proteins representing the FVO and 3D7 alleles in 1:1 mass ratio, formulated with Montanide(®) ISA 720 as a water-in oil emulsion. In order to develop the AMA1-C1/ISA 720 vaccine for human use, it was important to determine the shelf life of this formulation. Previously it was found 267 mM glycine stabilized the proteins in Montanide(®) ISA 720 formulations for a short period of time at 2-8°C [25]. We now test the long term stability of AMA1-C1 at 10 and 40 μg/mL formulated with Montanide(®) ISA 720 with 50mM glycine as a stabilizer. Stability of AMA1-C1/ISA 720 at different time points following formulation (0, 5, 12 or 18 months) was evaluated by determining the mean particle size (diameter of the mean droplet volume), total protein content by a Modified Lowry assay, identity and integrity using western blot and SDS-PAGE. Our results showed that the mean particle size of these emulsions increased over time, whereas protein content, as determined by an ELISA method using a monoclonal antibody against penta-his, decreased over time. For the 10 μg/mL AMA1-C1/ISA 720 vaccine, the protein content was 6.5±2.2 μg/mL, and for the 40 μg/mL AMA1-C1/ISA 720 vaccine, the protein content was only 8.2±2.3 μg/mL after 18 months of storage at 2-8°C. These results suggest that the integrity of the protein was affected by long-term storage. The results of the present study indicate that the AMA1-C1/ISA 720 emulsion was unstable after 12 months of storage, after which AMA1-C1 proteins were partially degraded.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.vaccine.2011.03.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3089892PMC
May 2011

Evaluation of the immunogenicity and biological activity of the Citrobacter freundii Vi-CRM197 conjugate as a vaccine for Salmonella enterica serovar Typhi.

Clin Vaccine Immunol 2011 Mar 19;18(3):460-8. Epub 2011 Jan 19.

Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy.

Typhoid fever remains a major health problem in developing countries. Young children are at high risk, and a vaccine effective for this age group is urgently needed. Purified capsular polysaccharide from Salmonella enterica serovar Typhi (Vi) is licensed as a vaccine, providing 50 to 70% protection in individuals older than 5 years. However, this vaccine is ineffective in infants. Vi conjugated to a carrier protein (i.e., an exoprotein A mutant from Pseudomonas aeruginosa [rEPA]) is highly immunogenic, provides long-term protection, and shows more than 90% protective efficacy in children 2 to 5 years old. Here, we describe an alternative glycoconjugate vaccine for S. Typhi, Vi-CRM(197), where Vi was obtained from Citrobacter freundii WR7011 and CRM(197), the mutant diphtheria toxin protein, was used as the carrier. We investigated the optimization of growth conditions for Vi production from C. freundii WR7011 and the immunogenicity of Vi-CRM(197) conjugates in mice. The optimal saccharide/protein ratio of the glycoconjugates was identified for the best antibody production. We also demonstrated the ability of this new vaccine to protect mice against challenge with Vi-positive Salmonella enterica serovar Typhimurium.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/CVI.00387-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3067394PMC
March 2011

Conjugate vaccines for enteric fever: proceedings of a meeting organized in New Delhi, India in 2009.

J Infect Dev Ctries 2010 Jun 30;4(6):404-11. Epub 2010 Jun 30.

Novartis Vaccines Institute for Global Health, 53100 Siena, Italy.

Enteric fever is responsible for significant morbidity in South Asia and high prevalence of severe disease is seen in children under two years of age. Effective typhoid vaccines are available, but they cannot be used for children under two years of age and also have some limitations in older age groups. Participants supported development of a Salmonella Typhi conjugate vaccine able to induce effective, long-lasting immunity in young children. The role of Salmonella Paratyphi A as a cause of enteric fever was discussed and consensus reached that a bivalent S. Typhi-S. Paratyphi A conjugate vaccine is highly desirable; however, considering disease epidemiology and the advanced status of vaccine development, rapid introduction of monovalent S. Typhi conjugate vaccine into vaccination programs of South Asia was recommended. Prevention should be emphasized, available vaccines used, and efforts toward improving sanitation continued. Success of the new vaccine will depend on several factors, including delivery costs and governmental ability to adopt and implement suitable immunization programs. To ensure good immunization coverage, the conjugate vaccine could be administered either to young infants, concomitantly with infant EPI vaccines, or to older infants, concomitantly with measles vaccine, currently given at 9 to 12 months. The need for new combination vaccines, containing both EPI and typhoid antigens, was discussed as a tool to increase coverage and reduce the number of injections and priority conflicts in a crowded infant vaccination schedule. However, stand-alone enteric fever conjugate vaccines would allow more flexibility to immunize different age groups and therefore should be rapidly developed.
View Article and Find Full Text PDF

Download full-text PDF

Source
June 2010

Phase 1 trial of the Plasmodium falciparum blood stage vaccine MSP1(42)-C1/Alhydrogel with and without CPG 7909 in malaria naïve adults.

PLoS One 2010 Jan 22;5(1):e8787. Epub 2010 Jan 22.

Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases/National Institutes of Health, Rockville, Maryland, USA.

Background: Merozoite surface protein 1(42) (MSP1(42)) is a leading blood stage malaria vaccine candidate. In order to induce immune responses that cover the major antigenic polymorphisms, FVO and 3D7 recombinant proteins of MSP1(42) were mixed (MSP1(42)-C1). To improve the level of antibody response, MSP1(42)-C1 was formulated with Alhydrogel plus the novel adjuvant CPG 7909.

Methods: A Phase 1 clinical trial was conducted in healthy malaria-naïve adults at the Center for Immunization Research in Washington, D.C., to evaluate the safety and immunogenicity of MSP1(42)-C1/Alhydrogel +/- CPG 7909. Sixty volunteers were enrolled in dose escalating cohorts and randomized to receive three vaccinations of either 40 or 160 microg protein adsorbed to Alhydrogel +/- 560 microg CPG 7909 at 0, 1 and 2 months.

Results: Vaccinations were well tolerated, with only one related adverse event graded as severe (Grade 3 injection site erythema) and all other vaccine related adverse events graded as either mild or moderate. Local adverse events were more frequent and severe in the groups receiving CPG. The addition of CPG enhanced anti-MSP1(42) antibody responses following vaccination by up to 49-fold two weeks after second immunization and 8-fold two weeks after the third immunization when compared to MSP1(42)-C1/Alhydrogel alone (p<0.0001). After the third immunization, functionality of the antibody was tested by an in vitro growth inhibition assay. Inhibition was a function of antibody titer, with an average of 3% (range -2 to 10%) in the non CPG groups versus 14% (3 to 32%) in the CPG groups.

Conclusion/significance: The favorable safety profile and high antibody responses induced with MSP1(42)-C1/Alhydrogel + CPG 7909 are encouraging. MSP1(42)-C1/Alhydrogel is being combined with other blood stage antigens and will be taken forward in a formulation adjuvanted with CPG 7909.

Trial Registration: ClinicalTrials.gov Identifier: NCT00320658.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0008787PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2809736PMC
January 2010