284 results match your criteria ty21a


Age-dependency of terminal ileum tissue resident memory T cell responsiveness profiles to S. Typhi following oral Ty21a immunization in humans.

Immun Ageing 2021 Apr 19;18(1):19. Epub 2021 Apr 19.

Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.

Background: The impact of aging on the immune system is unequivocal and results in an altered immune status termed immunosenescence. In humans, the mechanisms of immunosenescence have been examined almost exclusively in blood. However, most immune cells are present in tissue compartments and exhibit differential cell (e. Read More

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Enteric fever.

BMJ 2021 02 26;372:n437. Epub 2021 Feb 26.

Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK.

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February 2021

Impact of BCG revaccination on the response to unrelated vaccines in a Ugandan adolescent birth cohort: randomised controlled trial protocol C for the 'POPulation differences in VACcine responses' (POPVAC) programme.

BMJ Open 2021 02 16;11(2):e040430. Epub 2021 Feb 16.

Immunomodulation and Vaccines Programme, MRC/UVRI and LSHTM Uganda Research Unit, Entebbe, Wakiso, Uganda.

Introduction: There is evidence that BCG immunisation may protect against unrelated infectious illnesses. This has led to the postulation that administering BCG before unrelated vaccines may enhance responses to these vaccines. This might also model effects of BCG on unrelated infections. Read More

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February 2021

Nonclinical safety evaluation of oral recombinant anti-human papilloma virus vaccine (RHPV 16 & 18): Regulatory toxicology studies in mice, rats and rabbits - An innovative approach.

Vaccine 2021 01 31;39(5):853-863. Epub 2020 Dec 31.

Advanced Centre for Preclinical Toxicology Studies, ICMR-National Institute of Nutrition, Jamai-Osmania, Hyderabad 500007, India. Electronic address:

Aim: The human papilloma virus (HPV) type 16 and 18 causes nearly 70% of uterine cervical cancers. Oral administration of live Salmonella typhi Ty21a, expressing major capsid proteins (L1) of HPV 16 and 18 is a potential choice for immunization in adolescent girls under low resource settings. Present study aimed to assess the nonclinical safety of recombinant S. Read More

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January 2021

Multidose Priming and Delayed Boosting Improve PfSPZ Vaccine Efficacy against Heterologous P. falciparum Controlled Human Malaria Infection.

Clin Infect Dis 2020 Sep 12. Epub 2020 Sep 12.

Naval Medical Research Center Malaria Department, Silver Spring, MD.

Background: A live-attenuated Plasmodium falciparum (Pf) sporozoite (SPZ) vaccine (PfSPZ Vaccine) has shown up to 100% protection against controlled human malaria infection (CHMI) using homologous parasites (same Pf strain as in the vaccine). Using a more stringent CHMI, with heterologous parasites (different Pf strain), we assessed the impact of higher PfSPZ doses, a novel multi-dose prime regimen, and a delayed vaccine boost upon vaccine efficacy.

Methods: Four groups of 15 healthy, malaria-naïve adults were immunized. Read More

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September 2020

Differentially regulated promoters for antigen expression in Salmonella vaccine strains.

Vaccine 2020 05 4;38(26):4154-4161. Epub 2020 May 4.

Materno-fetal and Obstetrics Research Unit, Department Woman-Mother-Child, Lausanne University Hospital, Lausanne, Switzerland. Electronic address:

In most attenuated Salmonella enterica vaccines, heterologous antigens are expressed under the control of strong inducible promoters to ensure a high level of synthesis. Although high expression levels of the antigen can improve the immunogenicity of the vaccine, they might be toxic to the Salmonella carrier. Expression problems could be avoided by the use of promoters with specific characteristics with respect to strength and timing of expression. Read More

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Oral typhoid vaccine Ty21a elicits antigen-specific resident memory CD4 T cells in the human terminal ileum lamina propria and epithelial compartments.

J Transl Med 2020 02 25;18(1):102. Epub 2020 Feb 25.

Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.

Background: Salmonella enterica serovar Typhi (S. Typhi) is a highly invasive bacterium that infects the human intestinal mucosa and causes ~ 11.9-20. Read More

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February 2020

Differential functional patterns of memory CD4 and CD8 T-cells from volunteers immunized with Ty21a typhoid vaccine observed using a recombinant Escherichia coli system expressing S. Typhi proteins.

Vaccine 2020 01 16;38(2):258-270. Epub 2019 Oct 16.

Center for Vaccine Development and Global Health (CVD), Department of Pediatrics, University of Maryland School of Medicine, 685 West Baltimore Street, HSF1, Baltimore, MD 21201, USA.

It is widely accepted that CD4 and CD8 T-cells play a significant role in protection against Salmonella enterica serovar Typhi (S. Typhi), the causative agent of the typhoid fever. However, the antigen specificity of these T-cells remains largely unknown. Read More

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January 2020

Generating the Evidence for Typhoid Vaccine Introduction: Considerations for Global Disease Burden Estimates and Vaccine Testing Through Human Challenge.

Clin Infect Dis 2019 10;69(Suppl 5):S402-S407

Oxford Vaccine Group, Department of Paediatrics, University of Oxford, United Kingdom.

Typhoid fever has had a major impact on human populations, with the causative pathogen Salmonella enterica serovar Typhi implicated in many outbreaks through history. The current burden of disease is estimated at 11-18 million infections annually, with the majority of infections located in Africa and South Asia. Data that have been used to estimate burden are limited to a small number of blood-culture surveillance studies, largely from densely populated urban centers. Read More

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October 2019

Characteristics of regulatory T-cell populations before and after Ty21a typhoid vaccination in children and adults.

Clin Immunol 2019 06 4;203:14-22. Epub 2019 Apr 4.

Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA; Molecular Microbiology and Immunology Department, University of Maryland Graduate Program in Life Sciences, Baltimore, MD, USA; Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA. Electronic address:

Typhoid fever, caused by the pathogen Salmonella enterica serovar Typhi (S. Typhi), is a serious global health concern. Challenge studies with wild type S. Read More

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Salmonella Typhi outer membrane protein STIV is a potential candidate for vaccine development against typhoid and paratyphoid fever.

Immunobiology 2019 05 22;224(3):371-382. Epub 2019 Mar 22.

Division of Clinical Medicine, National Institute of Cholera and Enteric Diseases, P-33 Scheme-XM, C.I.T. Road, Beliaghata, Kolkata, 700010, India. Electronic address:

Enteric fever, caused by Salmonella enterica serovars, Typhi (S. Typhi) and Paratyphi (S. Paratyphi) is a major public health challenge for the developing nations. Read More

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Diversity of Salmonella Typhi-responsive CD4 and CD8 T cells before and after Ty21a typhoid vaccination in children and adults.

Int Immunol 2019 04;31(5):315-333

Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.

Typhoid fever is a life-threatening disease caused by the human-restricted pathogen Salmonella enterica serovar Typhi (S. Typhi). The oral live attenuated Ty21a typhoid vaccine protects against this severe disease by eliciting robust, multifunctional cell-mediated immunity (CMI), shown to be associated with protection in wild-type S. Read More

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Attenuated Oral Typhoid Vaccine Ty21a Elicits Lamina Propria and Intra-Epithelial Lymphocyte Tissue-Resident Effector Memory CD8 T Responses in the Human Terminal Ileum.

Front Immunol 2019 14;10:424. Epub 2019 Mar 14.

Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States.

Tissue-resident memory T cells (T) are newly defined memory T cells (T) distinct from circulating T subsets which have the potential to mount rapid protective immune responses at the site of infection. However, very limited information is available regarding the role and contribution of T in vaccine-mediated immune responses in humans at the site of infection. Here, we studied the role and contribution of tissue resident memory T cells (T) located in the terminal ileum (TI) (favored site of infection for . Read More

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Age-Associated Heterogeneity of Ty21a-Induced T Cell Responses to HLA-E Restricted Typhi Antigen Presentation.

Front Immunol 2019 4;10:257. Epub 2019 Mar 4.

Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States.

Human-restricted serovar Typhi (. Typhi) is the causative agent of typhoid fever-a life-threatening disease of great global health significance, particularly in the developing world. Ty21a is an oral live-attenuated vaccine that protects against the development of typhoid disease in part by inducing robust T cell responses, among which multifunctional CD8 cytotoxic T lymphocytes (CTL) play an important role. Read More

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Publisher Correction: Clonal analysis of Salmonella-specific effector T cells reveals serovar-specific and cross-reactive T cell responses.

Nat Immunol 2019 Apr;20(4):514

MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.

In the version of this article initially published, the first affiliation lacked 'MRC'; the correct name of the institution is 'MRC Weatherall Institute of Molecular Medicine'. Two designations (SP110Y and ST110H) were incorrect in the legend to Fig. 6f,h,i. Read More

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Association between . Typhi-specific memory CD4+ and CD8+ T responses in the terminal ileum mucosa and in peripheral blood elicited by the live oral typhoid vaccine Ty21a in humans.

Hum Vaccin Immunother 2019 2;15(6):1409-1420. Epub 2019 Apr 2.

a Center for Vaccine Development and Global Health , University of Maryland School of Medicine , Baltimore , MD , USA.

CD4+ and CD8+ T subsets are essential components of the adaptive immune system which act in concert at the site of infections to effectively protect against pathogens. Very limited data is available in humans regarding the relationship between CD4+ and CD8+ . Typhi responsive cells in the terminal ileum mucosa (TI) and peripheral blood following Ty21a oral typhoid immunization. Read More

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Nonspecific effects of oral vaccination with live-attenuated Typhi strain Ty21a.

Sci Adv 2019 02 27;5(2):eaau6849. Epub 2019 Feb 27.

Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.

Epidemiological and immunological evidence suggests that some vaccines can reduce all-cause mortality through nonspecific changes made to innate immune cells. Here, we present the first data to describe the nonspecific immunological impact of oral vaccination with live-attenuated Typhi strain Ty21a. We vaccinated healthy adults with Ty21a and assessed aspects of innate and adaptive immunity over the course of 6 months. Read More

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February 2019

Intravesical Ty21a Vaccine Promotes Dendritic Cells and T Cell-Mediated Tumor Regression in the MB49 Bladder Cancer Model.

Cancer Immunol Res 2019 04 29;7(4):621-629. Epub 2019 Jan 29.

Department of Urology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.

Preclinical data show that intravesical instillation of Ty21a/Vivotif, a commercial vaccine against typhoid fever, is an effective alternative option to standard Bacillus Calmette-Guérin (BCG) immunotherapy for non-muscle-invasive bladder cancer (NMIBC). Here, we characterized the inflammatory effects of Ty21a on the bladder and investigated the immune mechanisms underlying tumor regression toward the use of this bacterial vaccine in NMIBC patients. MB49 bladder tumor-bearing mice had significantly improved survival after intravesical instillations of Ty21a doses of 10 to 10 colony-forming units. Read More

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Manipulation of Typhi Gene Expression Impacts Innate Cell Responses in the Human Intestinal Mucosa.

Front Immunol 2018 1;9:2543. Epub 2018 Nov 1.

Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States.

Although immunity induced by typhoid fever is moderated and short-lived, typhoid vaccination with the attenuated Ty21a oral vaccine generates long-lasting protection rates reaching up to 92%. Thus, there are important differences on how wild-type and typhoid vaccine strains stimulate host immunity. We hypothesize that vaccine strains with different mutations might affect gut inflammation and intestinal permeability by different mechanisms. Read More

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September 2019

Current Clinical Trials in Non-muscle Invasive Bladder Cancer.

Curr Urol Rep 2018 Oct 24;19(12):101. Epub 2018 Oct 24.

Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Level 6, 2775 Laurel St, Vancouver, BC, V6N 2W6, Canada.

Purpose Of Review: As our molecular understanding of bladder cancer continues to advance, more and more novel agents are entering clinical trials across the spectrum of bladder cancer stages. The clinical trial activity for non-muscle invasive bladder cancer (NMIBC) has been boosted further by the evolution of specific disease states that set more uniform inclusion criteria for clinical trial design. Here, we aimed to review the current clinical trials landscape in non-muscle invasive bladder cancer with respect to these disease states. Read More

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October 2018

Effect of the live oral attenuated typhoid vaccine, Ty21a, on systemic and terminal ileum mucosal CD4+ T memory responses in humans.

Int Immunol 2019 02;31(2):101-116

Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.

Our current understanding of CD4+ T-cell-mediated immunity (CMI) elicited by the oral live attenuated typhoid vaccine Ty21a is primarily derived from studies using peripheral blood. Very limited data are available in humans regarding mucosal immunity (especially CD4+ T) at the site of infection (e.g. Read More

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February 2019

The Impact of Vaccination and Prior Exposure on Stool Shedding of Salmonella Typhi and Salmonella Paratyphi in 6 Controlled Human Infection Studies.

Clin Infect Dis 2019 04;68(8):1265-1273

Oxford Vaccine Group, Department of Paediatrics, University of Oxford.

Background: Shedding of Salmonella Typhi or Paratyphi in the stool or urine leads to contamination of food or water, which is a prerequisite for transmission of enteric fever. Currently, there are limited data on the effect of vaccination or prior exposure on stool shedding.

Methods: Six Salmonella Typhi or Paratyphi human challenge studies were conducted between 2011 and 2017. Read More

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Alive attenuated Salmonella as a cargo shuttle for smart carrying of gold nanoparticles to tumour hypoxic regions.

J Drug Target 2019 03 3;27(3):315-324. Epub 2018 Oct 3.

d Department of Chemistry , University of Isfahan , Isfahan , Iran.

In the present study, alive attenuated Salmonella typhi Ty21a was introduced as a vehicle for smart delivery of gold nanoparticles to the tumours' hypoxic regions. At the first step, the uptakes of gold nanoparticles with seven different decorations by S. typhi Ty21a was investigated using flow cytometry and inductively coupled plasma optical emission spectroscopy. Read More

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Longevity of duodenal and peripheral T-cell and humoral responses to live-attenuated Salmonella Typhi strain Ty21a.

Vaccine 2018 07 27;36(31):4725-4733. Epub 2018 Jun 27.

Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, UK; Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, Queen Elizabeth Central Hospital, Malawi. Electronic address:

Background: We have previously demonstrated that polyfunctional Ty21a-responsive CD4 and CD8 T cells are generated at the duodenal mucosa 18 days following vaccination with live-attenuated S. Typhi (Ty21a). The longevity of cellular responses has been assessed in peripheral blood, but persistence of duodenal responses is unknown. Read More

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Vaccines for preventing typhoid fever.

Cochrane Database Syst Rev 2018 05 31;5:CD001261. Epub 2018 May 31.

Cochrane Infectious Diseases Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK, L3 5QA.

Background: Typhoid fever and paratyphoid fever continue to be important causes of illness and death, particularly among children and adolescents in south-central and southeast Asia. Two typhoid vaccines are widely available, Ty21a (oral) and Vi polysaccharide (parenteral). Newer typhoid conjugate vaccines are at varying stages of development and use. Read More

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Retinoic acid elicits a coordinated expression of gut homing markers on T lymphocytes of Zambian men receiving oral Vivotif, but not Rotarix, Dukoral or OPVERO vaccines.

Vaccine 2018 06 22;36(28):4134-4141. Epub 2018 May 22.

Tropical Gastroenterology & Nutrition Group, Department of Medicine, School of Medicine, University of Zambia, Lusaka, Zambia; Blizard Institute, Barts & The London School of Medicine, Queen Mary University of London, London, UK.

All-trans retinoic acid (ATRA) up-regulates, in laboratory animals, the expression of the gut homing markers α4β7 integrin and CCR9 on lymphocytes, increasing their gut tropism. Here, we show that, in healthy adult volunteers, ATRA induced an increase of these gut homing markers on T cells in vivo in a time dependent manner. The coordinated increase of α4β7 and CCR9 by ATRA was seen in 57% (12/21) of volunteers and only when given together with an oral Vivotif vaccine. Read More

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Conversion of RpoS Attenuated Serovar Typhi Vaccine Strains to RpoS Improves Their Resistance to Host Defense Barriers.

mSphere 2018 Jan-Feb;3(1). Epub 2018 Feb 28.

Department of Infectious Disease and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.

The vast majority of live attenuated typhoid vaccines are constructed from the serovar Typhi strain Ty2, which is devoid of a functioning alternative sigma factor, RpoS, due to the presence of a frameshift mutation. RpoS is a specialized sigma factor that plays an important role in the general stress response of a number of Gram-negative organisms, including . Previous studies have demonstrated that this sigma factor is necessary for survival following exposure to acid, hydrogen peroxide, nutrient-limiting conditions, and starvation. Read More

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February 2018

Typhi Bactericidal Antibodies Reduce Disease Severity but Do Not Protect against Typhoid Fever in a Controlled Human Infection Model.

Front Immunol 2017 17;8:1916. Epub 2018 Jan 17.

Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.

Effective vaccines against , a major cause of febrile illness in tropical regions, can have a significant effect as a disease control measure. Earlier work has shown that immunization with either of two Typhi vaccines, licensed Ty21a or candidate M01ZH09, did not provide full immunity in a controlled human infection model. Here, we describe the human humoral immune responses to these oral vaccines and their functional role in protection after challenge with . Read More

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January 2018

Protection against inhalation anthrax by immunization with Ty21a stably producing protective antigen of .

NPJ Vaccines 2017 15;2:17. Epub 2017 Jun 15.

Protein Potential LLC, Rockville, MD 20850 USA.

The national blueprint for biodefense concluded that the United States is underprepared for biological threats. The licensed anthrax vaccine absorbed vaccine, BioThrax, requires administration of at least 3-5 intramuscular doses. The anthrax vaccine absorbed vaccine consists of complex cell-free culture filtrates of a toxigenic strain and causes tenderness at the injection site and significant adverse events. Read More

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In vivo tropism of Salmonella Typhi toxin to cells expressing a multiantennal glycan receptor.

Nat Microbiol 2018 02 4;3(2):155-163. Epub 2017 Dec 4.

Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.

Typhoid fever is a life-threatening disease, but little is known about the molecular bases for its unique clinical presentation. Typhoid toxin, a unique virulence factor of Salmonella Typhi (the cause of typhoid fever), recapitulates in an animal model many symptoms of typhoid fever. Typhoid toxin binding to its glycan receptor Neu5Ac is central, but, due to the ubiquity of Neu5Ac, how typhoid toxin causes specific symptoms remains elusive. Read More

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February 2018