Publications by authors named "Sylvie Bertholet"

58 Publications

2020 White Paper on Recent Issues in Bioanalysis: Vaccine Assay Validation, qPCR Assay Validation, QC for CAR-T Flow Cytometry, NAb Assay Harmonization and ELISpot Validation ( - Recommendations on Immunogenicity Assay Strategies, NAb Assays, Biosimilars and FDA/EMA Immunogenicity Guidance/Guideline, Gene & Cell Therapy and Vaccine Assays).

Bioanalysis 2021 Mar 3;13(6):415-463. Epub 2021 Feb 3.

US FDA, Silver Spring, MD, USA.

The 14 edition of the Workshop on Recent Issues in Bioanalysis (14 WRIB) was held virtually on June 15-29, 2020 with an attendance of over 1000 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations, and regulatory agencies worldwide. The 14 WRIB included three Main Workshops, seven Specialized Workshops that together spanned 11 days in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy and vaccine. Moreover, a comprehensive vaccine assays track; an enhanced cytometry track and updated Industry/Regulators consensus on BMV of biotherapeutics by LCMS were special features in 2020. As in previous years, this year's WRIB continued to gather a wide diversity of international industry opinion leaders and regulatory authority experts working on both small and large molecules to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance and achieving scientific excellence on bioanalytical issues. This 2020 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the Global Bioanalytical Community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2020 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations on Vaccine, Gene/Cell Therapy, NAb Harmonization and Immunogenicity). Part 1 (Innovation in Small Molecules, Hybrid LBA/LCMS & Regulated Bioanalysis), Part 2A (BAV, PK LBA, Flow Cytometry Validation and Cytometry Innovation) and Part 2B (Regulatory Input) are published in volume 13 of Bioanalysis, issues 4 and 5 (2020), respectively.
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http://dx.doi.org/10.4155/bio-2021-0007DOI Listing
March 2021

2020 White Paper on Recent Issues in Bioanalysis: BAV Guidance, CLSI H62, Biotherapeutics Stability, Parallelism Testing, CyTOF and Regulatory Feedback ( - Recommendations on Biotherapeutics Stability, PK LBA Regulated Bioanalysis, Biomarkers Assays, Cytometry Validation & Innovation - Regulatory Agencies' Inputs on Bioanalysis, Biomarkers, Immunogenicity, Gene & Cell Therapy and Vaccine).

Bioanalysis 2021 Mar 29;13(5):295-361. Epub 2021 Jan 29.

Regeneron Pharmaceuticals, Tarrytown, NY, USA.

The 14 edition of the Workshop on Recent Issues in Bioanalysis (14 WRIB) was held virtually on June 15-29, 2020 with an attendance of over 1000 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations, and regulatory agencies worldwide. The 14 WRIB included three Main Workshops, seven Specialized Workshops that together spanned 11 days in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy and vaccine. Moreover, a comprehensive vaccine assays track; an enhanced cytometry track and updated Industry/Regulators consensus on BMV of biotherapeutics by LCMS were special features in 2020. As in previous years, this year's WRIB continued to gather a wide diversity of international industry opinion leaders and regulatory authority experts working on both small and large molecules to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance and achieving scientific excellence on bioanalytical issues. This 2020 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the Global Bioanalytical Community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2020 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication covers the recommendations on (Part 2A) BAV, PK LBA, Flow Cytometry Validation and Cytometry Innovation and (Part 2B) Regulatory Input. Part 1 (Innovation in Small Molecules, Hybrid LBA/LCMS & Regulated Bioanalysis), Part 3 (Vaccine, Gene/Cell Therapy, NAb Harmonization and Immunogenicity) are published in volume 13 of Bioanalysis, issues 4, and 6 (2021), respectively.
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http://dx.doi.org/10.4155/bio-2021-0005DOI Listing
March 2021

Technological approaches to streamline vaccination schedules, progressing towards single-dose vaccines.

NPJ Vaccines 2020 18;5:88. Epub 2020 Sep 18.

GSK, Slaoui Center for Vaccines Research, Rockville, MD 20850 USA.

Vaccines represent the most successful medical intervention in history, with billions of lives saved. Although multiple doses of the same vaccine are typically required to reach an adequate level of protection, it would be advantageous to develop vaccines that induce protective immunity with fewer doses, ideally just one. Single-dose vaccines would be ideal to maximize vaccination coverage, help stakeholders to greatly reduce the costs associated with vaccination, and improve patient convenience. Here we describe past attempts to develop potent single dose vaccines and explore the reasons they failed. Then, we review key immunological mechanisms of the vaccine-specific immune responses, and how innovative technologies and approaches are guiding the preclinical and clinical development of potent single-dose vaccines. By modulating the spatio-temporal delivery of the vaccine components, by providing the appropriate stimuli to the innate immunity, and by designing better antigens, the new technologies and approaches leverage our current knowledge of the immune system and may synergize to enable the rational design of next-generation vaccination strategies. This review provides a rational perspective on the possible development of future single-dose vaccines.
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http://dx.doi.org/10.1038/s41541-020-00238-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7501859PMC
September 2020

Formulation Design, Optimization and In Vivo Evaluations of an α-Tocopherol-Containing Self-Emulsified Adjuvant System using Inactivated Influenza Vaccine.

J Control Release 2019 12 31;316:12-21. Epub 2019 Oct 31.

GSK, Slaoui Centre for Vaccines Research, Rockville, MD, 20850, USA.

α-Tocopherol has been used as an immune supplement in humans, as an emulsion adjuvant component in several veterinary vaccines as well as an immunomodulatory component of AS03, an emulsion adjuvant that was used in an H1N1 pandemic vaccine (Pandemrix). AS03 is manufactured using microfluidization and high-pressure homogenization. Such high energy and complex manufacturing processes make it difficult and expensive to produce emulsion adjuvants on a large scale, especially in developing countries. In this study we have explored simpler, comparatively inexpensive methods, to formulate emulsion adjuvants containing α-tocopherol, that have the potential to be made in any well-established scale-up facility. This might facilitate producing and stock-piling adjuvant doses and therefore aide in pandemic preparedness. We used design of experiment as a tool to explore incorporating α-tocopherol into self-emulsified systems containing squalene oil and polysorbate 80. We created novel self-emulsified adjuvant systems (SE-AS) and evaluated their potency in vivo in BALB/c mice with inactivated quadrivalent influenza vaccine (QIV) and tested the cellular and humoral immune responses against the four vaccine strains.
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http://dx.doi.org/10.1016/j.jconrel.2019.10.042DOI Listing
December 2019

Novel Platforms for the Development of a Universal Influenza Vaccine.

Front Immunol 2018 23;9:600. Epub 2018 Mar 23.

GSK, Research and Development Center, Siena, Italy.

Despite advancements in immunotherapeutic approaches, influenza continues to cause severe illness, particularly among immunocompromised individuals, young children, and elderly adults. Vaccination is the most effective way to reduce rates of morbidity and mortality caused by influenza viruses. Frequent genetic shift and drift among influenza-virus strains with the resultant disparity between circulating and vaccine virus strains limits the effectiveness of the available conventional influenza vaccines. One approach to overcome this limitation is to develop a universal influenza vaccine that could provide protection against all subtypes of influenza viruses. Moreover, the development of a novel or improved universal influenza vaccines may be greatly facilitated by new technologies including virus-like particles, T-cell-inducing peptides and recombinant proteins, synthetic viruses, broadly neutralizing antibodies, and nucleic acid-based vaccines. This review discusses recent scientific advances in the development of next-generation universal influenza vaccines.
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http://dx.doi.org/10.3389/fimmu.2018.00600DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5877485PMC
May 2019

A phase I, randomized, controlled, dose-ranging study of investigational acellular pertussis (aP) and reduced tetanus-diphtheria-acellular pertussis (TdaP) booster vaccines in adults.

Hum Vaccin Immunother 2018 01 27;14(1):45-58. Epub 2017 Nov 27.

b GSK, Vaccines , Siena , Italy.

Despite high vaccination coverage worldwide, pertussis has re-emerged in many countries. This randomized, controlled, observer-blind phase I study and extension study in Belgium (March 2012-June 2015) assessed safety and immunogenicity of investigational acellular pertussis vaccines containing genetically detoxified pertussis toxin (PT) (NCT01529645; NCT02382913). 420 healthy adults (average age: 26.8 ± 5.5 years, 60% female) were randomized to 1 of 10 vaccine groups: 3 investigational aP vaccines (containing pertussis antigens PT, filamentous hemagglutinin [FHA] and pertactin [PRN] at different dosages), 6 investigational TdaP (additionally containing tetanus toxoid [TT] and diphtheria toxoid [DT]), and 1 TdaP comparator containing chemically inactivated PT. Antibody responses were evaluated on days 1, 8, 30, 180, 365, and approximately 3 years post-booster vaccination. Cell-mediated immune responses and PT neutralization were evaluated in a subset of participants in pre-selected groups. Local and systemic adverse events (AEs), and unsolicited AEs were collected through day 7 and 30, respectively; serious AEs and AEs leading to study withdrawal were collected through day 365 post-vaccination. Antibody responses against pertussis antigens peaked at day 30 post-vaccination and then declined but remained above baseline level at approximately 3 years post-vaccination. Responses to FHA and PRN were correlated to antigen dose. Antibody responses specific to PT, toxin neutralization activity and persistence induced by investigational formulations were similar or significantly higher than the licensed vaccine, despite lower PT doses. Of 15 serious AEs, none were considered vaccination-related; 1 led to study withdrawal (premature labor, day 364; aP4 group). This study confirmed the potential benefits of genetically detoxified PT antigen. All investigational study formulations were well tolerated.
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http://dx.doi.org/10.1080/21645515.2017.1385686DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5791588PMC
January 2018

Staphylococcus aureus-dependent septic arthritis in murine knee joints: local immune response and beneficial effects of vaccination.

Sci Rep 2016 11 30;6:38043. Epub 2016 Nov 30.

GSK Vaccines, Via Fiorentina 1, Siena, 53100, Italy.

Staphylococcus aureus is the major cause of human septic arthritis and osteomyelitis, which deserve special attention due to their rapid evolution and resistance to treatment. The progression of the disease depends on both bacterial presence in situ and uncontrolled disruptive immune response, which is responsible for chronic disease. Articular and bone infections are often the result of blood bacteremia, with the knees and hips being the most frequently infected joints showing the worst clinical outcome. We report the development of a hematogenous model of septic arthritis in murine knees, which progresses from an acute to a chronic phase, similarly to what occurs in humans. Characterization of the local and systemic inflammatory and immune responses following bacterial infection brought to light specific signatures of disease. Immunization of mice with the vaccine formulation we have recently described (4C-Staph), induced a strong antibody response and specific CD4+ effector memory T cells, and resulted in reduced bacterial load in the knee joints, a milder general inflammatory state and protection against bacterial-mediated cellular toxicity. Possible correlates of protection are finally proposed, which might contribute to the development of an effective vaccine for human use.
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http://dx.doi.org/10.1038/srep38043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5128924PMC
November 2016

Self-Amplifying mRNA Vaccines Expressing Multiple Conserved Influenza Antigens Confer Protection against Homologous and Heterosubtypic Viral Challenge.

PLoS One 2016 15;11(8):e0161193. Epub 2016 Aug 15.

Novartis Vaccines, S.r.l., Siena, Italy.

Current hemagglutinin (HA)-based seasonal influenza vaccines induce vaccine strain-specific neutralizing antibodies that usually fail to provide protection against mismatched circulating viruses. Inclusion in the vaccine of highly conserved internal proteins such as the nucleoprotein (NP) and the matrix protein 1 (M1) was shown previously to increase vaccine efficacy by eliciting cross-reactive T-cells. However, appropriate delivery systems are required for efficient priming of T-cell responses. In this study, we demonstrated that administration of novel self-amplifying mRNA (SAM®) vectors expressing influenza NP (SAM(NP)), M1 (SAM(M1)), and NP and M1 (SAM(M1-NP)) delivered with lipid nanoparticles (LNP) induced robust polyfunctional CD4 T helper 1 cells, while NP-containing SAM also induced cytotoxic CD8 T cells. Robust expansions of central memory (TCM) and effector memory (TEM) CD4 and CD8 T cells were also measured. An enhanced recruitment of NP-specific cytotoxic CD8 T cells was observed in the lungs of SAM(NP)-immunized mice after influenza infection that paralleled with reduced lung viral titers and pathology, and increased survival after homologous and heterosubtypic influenza challenge. Finally, we demonstrated for the first time that the co-administration of RNA (SAM(M1-NP)) and protein (monovalent inactivated influenza vaccine (MIIV)) was feasible, induced simultaneously NP-, M1- and HA-specific T cells and HA-specific neutralizing antibodies, and enhanced MIIV efficacy against a heterologous challenge. In conclusion, systemic administration of SAM vectors expressing conserved internal influenza antigens induced protective immune responses in mice, supporting the SAM® platform as another promising strategy for the development of broad-spectrum universal influenza vaccines.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161193PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4985159PMC
July 2017

Early Rise of Blood T Follicular Helper Cell Subsets and Baseline Immunity as Predictors of Persisting Late Functional Antibody Responses to Vaccination in Humans.

PLoS One 2016 23;11(6):e0157066. Epub 2016 Jun 23.

Novartis Vaccines & Diagnostics S.r.l., Siena, Italy.

CD4+ T follicular helper cells (T(FH)) have been identified as the T-cell subset specialized in providing help to B cells for optimal activation and production of high affinity antibody. We recently demonstrated that the expansion of peripheral blood influenza-specific CD4(+)IL-21(+)ICOS1(+) T helper (T(H)) cells, three weeks after vaccination, associated with and predicted the rise of protective neutralizing antibodies to avian H5N1. In this study, healthy adults were vaccinated with plain seasonal trivalent inactivated influenza vaccine (TIIV), MF59(®)-adjuvanted TIIV (ATIIV), or saline placebo. Frequencies of circulating CD4(+) T(FH)1 ICOS(+) T(FH) cells and H1N1-specific CD4(+-)IL-21(+)ICOS(+) CXCR5(+) T(FH) and CXCR5(-) T(H) cell subsets were determined at various time points after vaccination and were then correlated with hemagglutination inhibition (HI) titers. All three CD4(+) T cell subsets expanded in response to TIIV and ATIIV, and peaked 7 days after vaccination. To demonstrate that these T(FH) cell subsets correlated with functional antibody titers, we defined an alternative endpoint metric, decorrelated HI (DHI), which removed any correlation between day 28/day 168 and day 0 HI titers, to control for the effect of preexisting immunity to influenza vaccine strains. The numbers of total circulating CD4(+)T(FH)1 ICOS(+) cells and of H1N1-specific CD4(+)IL-21(+)ICOS(+) CXCR5(+), measured at day 7, were significantly associated with day 28, and day 28 and 168 DHI titers, respectively. Altogether, our results show that CD4(+) T(FH) subsets may represent valuable biomarkers of vaccine-induced long-term functional immunity.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0157066PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918887PMC
July 2017

Anticipating policy considerations for a future HIV vaccine: a preliminary study.

Vaccine 2016 07 4;34(32):3697-701. Epub 2016 Apr 4.

Department of Medical Biotechnology, University of Siena, Italy.

Background: New human immunodeficiency virus (HIV) infections continue to occur worldwide. Despite previous failures, there is renewed optimism about developing an efficacious HIV prophylactic vaccine following the 31.2% vaccine efficacy (modified intention to treat analysis) achieved in the RV-144 trial. Intense efforts at characterising the immune responses in the trial participants who appeared to gain some protection from the candidate vaccine are ongoing to delineate correlates of protection. However, the characteristics of a vaccine suitable for programmatic introduction in high prevalence areas remain undefined.

Aims: We set out to ascertain the vaccination policies and strategies that policy makers involved in vaccine introductions would advise were a candidate HIV vaccine to become available.

Methods: Structured questionnaires in both English and French were self-administered to consenting policy makers such as members of National Immunisation Technical Advisory Groups. Members from three out of the six WHO regional groups were purposively reached for their responses.

Results: Thirty-seven key opinion leaders were approached through self-administered questionnaires delivered by e-mail or in person. Nine responses were received, representing a 24.3% response rate. The responses received were from three [Africa (6), Americas (1) and Europe (2)] out of the six WHO regions. All respondents would prioritise the vaccination of commercial sex workers over other risk groups if there was an efficacious HIV vaccine. Vaccine efficacy was considered to be the most important factor, ahead of vaccine safety and cost, in determining the acceptability of a new prophylactic HIV vaccine.

Conclusions: It is expected that the first generation HIV vaccines may be modestly efficacious. However, even a modestly efficacious vaccine might curtail the spread of HIV if universal or near-universal coverage is achieved. It is important to anticipate policy discussions which would influence how rapidly an HIV vaccine would be rolled-out programmatically to achieve maximum impact.
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http://dx.doi.org/10.1016/j.vaccine.2016.03.086DOI Listing
July 2016

Positive Contribution of Adjuvanted Influenza Vaccines to the Resolution of Bacterial Superinfections.

J Infect Dis 2016 06 9;213(12):1876-85. Epub 2016 Feb 9.

GSK Vaccines S.r.l., Vaccines Research Center, Siena.

Background: Most preclinical studies assess vaccine effectiveness in single-pathogen infection models. This is unrealistic given that humans are continuously exposed to different commensals and pathogens in sequential and mixed infections. Accordingly, complications from secondary bacterial infection are a leading cause of influenza-associated morbidity and mortality. New vaccination strategies are needed to control infections on simultaneous fronts.

Methods: We compared different anti-influenza vaccines for their protective potential in a model of viral infection with bacterial superinfection. Mice were immunized with H1N1/A/California/7/2009 subunit vaccines, formulated with different adjuvants inducing either T-helper type 1 (Th1) (MF59 plus CpG)-, Th1/2 (MF59)-, or Th17 (LTK63)-prone immune responses and were sequentially challenged with mouse-adapted influenza virus H1N1/A/Puerto Rico/8/1934 and Staphylococcus aureus USA300, a clonotype emerging as a leading contributor in postinfluenza pneumonia in humans.

Results: Unadjuvanted vaccine controlled single viral infection, yet mice had considerable morbidity from viral disease and bacterial superinfection. In contrast, all adjuvanted vaccines efficiently protected mice in both conditions. Interestingly, the Th1-inducing formulation was superior to Th1/2 or Th17 inducers.

Conclusions: Our studies should help us better understand how differential immunity to influenza skews immune responses toward coinfecting bacteria and discover novel modes to prevent bacterial superinfections in the lungs of persons with influenza.
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http://dx.doi.org/10.1093/infdis/jiw048DOI Listing
June 2016

One Dose of Staphylococcus aureus 4C-Staph Vaccine Formulated with a Novel TLR7-Dependent Adjuvant Rapidly Protects Mice through Antibodies, Effector CD4+ T Cells, and IL-17A.

PLoS One 2016 26;11(1):e0147767. Epub 2016 Jan 26.

Novartis Vaccines and Diagnostics, S.r.l., Research Center, Siena, Italy.

A rapidly acting, single dose vaccine against Staphylococcus aureus would be highly beneficial for patients scheduled for major surgeries or in intensive care units. Here we show that one immunization with a multicomponent S. aureus candidate vaccine, 4C-Staph, formulated with a novel TLR7-dependent adjuvant, T7-alum, readily protected mice from death and from bacterial dissemination, both in kidney abscess and peritonitis models, outperforming alum-formulated vaccine. This increased efficacy was paralleled by higher vaccine-specific and α-hemolysin-neutralizing antibody titers and Th1/Th17 cell responses. Antibodies played a crucial protective role, as shown by the lack of protection of 4C-Staph/T7-alum vaccine in B-cell-deficient mice and by serum transfer experiments. Depletion of effector CD4+ T cells not only reduced survival but also increased S. aureus load in kidneys of mice immunized with 4C-Staph/T7-alum. The role of IL-17A in the control of bacterial dissemination in 4C-Staph/T7-alum vaccinated mice was indicated by in vivo neutralization experiments. We conclude that single dose 4C-Staph/T7-alum vaccine promptly and efficiently protected mice against S. aureus through the combined actions of antibodies, CD4+ effector T cells, and IL-17A. These data suggest that inclusion of an adjuvant that induces not only fast antibody responses but also IL-17-producing cell-mediated effector responses could efficaciously protect patients scheduled for major surgeries or in intensive care units.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147767PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4727907PMC
July 2016

Induction of Broad-Based Immunity and Protective Efficacy by Self-amplifying mRNA Vaccines Encoding Influenza Virus Hemagglutinin.

J Virol 2016 01 14;90(1):332-44. Epub 2015 Oct 14.

Novartis Vaccines and Diagnostics S.r.l., Siena, Italy

Unlabelled: Seasonal influenza is a vaccine-preventable disease that remains a major health problem worldwide, especially in immunocompromised populations. The impact of influenza disease is even greater when strains drift, and influenza pandemics can result when animal-derived influenza virus strains combine with seasonal strains. In this study, we used the SAM technology and characterized the immunogenicity and efficacy of a self-amplifying mRNA expressing influenza virus hemagglutinin (HA) antigen [SAM(HA)] formulated with a novel oil-in-water cationic nanoemulsion. We demonstrated that SAM(HA) was immunogenic in ferrets and facilitated containment of viral replication in the upper respiratory tract of influenza virus-infected animals. In mice, SAM(HA) induced potent functional neutralizing antibody and cellular immune responses, characterized by HA-specific CD4 T helper 1 and CD8 cytotoxic T cells. Furthermore, mice immunized with SAM(HA) derived from the influenza A virus A/California/7/2009 (H1N1) strain (Cal) were protected from a lethal challenge with the heterologous mouse-adapted A/PR/8/1934 (H1N1) virus strain (PR8). Sera derived from SAM(H1-Cal)-immunized animals were not cross-reactive with the PR8 virus, whereas cross-reactivity was observed for HA-specific CD4 and CD8 T cells. Finally, depletion of T cells demonstrated that T-cell responses were essential in mediating heterologous protection. If the SAM vaccine platform proves safe, well tolerated, and effective in humans, the fully synthetic SAM vaccine technology could provide a rapid response platform to control pandemic influenza.

Importance: In this study, we describe protective immune responses in mice and ferrets after vaccination with a novel HA-based influenza vaccine. This novel type of vaccine elicits both humoral and cellular immune responses. Although vaccine-specific antibodies are the key players in mediating protection from homologous influenza virus infections, vaccine-specific T cells contribute to the control of heterologous infections. The rapid production capacity and the synthetic origin of the vaccine antigen make the SAM platform particularly exploitable in case of influenza pandemic.
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http://dx.doi.org/10.1128/JVI.01786-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4702536PMC
January 2016

MF59- and Al(OH)3-Adjuvanted Staphylococcus aureus (4C-Staph) Vaccines Induce Sustained Protective Humoral and Cellular Immune Responses, with a Critical Role for Effector CD4 T Cells at Low Antibody Titers.

Front Immunol 2015 7;6:439. Epub 2015 Sep 7.

Research Center, Novartis Vaccines and Diagnostics S.r.l. , Siena , Italy.

Staphylococcus aureus (S. aureus) is an important opportunistic pathogen that may cause invasive life-threatening infections, like sepsis and pneumonia. Due to the increasing antibiotic resistance, the development of an effective vaccine against S. aureus is needed. Although a correlate of protection against staphylococcal diseases is not yet established, several findings suggest that both antibodies and CD4 T cells might contribute to optimal immunity. In this study, we show that adjuvanting a multivalent vaccine (4C-Staph) with MF59, an oil-in-water emulsion licensed in human vaccines, further potentiated antigen-specific IgG titers and CD4 T-cell responses compared to alum and conferred protection in the peritonitis model of S. aureus infection. Moreover, we showed that MF59- and alum-adjuvanted 4C-Staph vaccines induced persistent antigen-specific humoral and T-cell responses, and protected mice from infection up to 4 months after immunization. Furthermore, 4C-Staph formulated with MF59 was used to investigate which immune compartment is involved in vaccine-induced protection. Using CD4 T cell-depleted mice or B cell-deficient mice, we demonstrated that both T and B-cell responses contributed to 4C-Staph vaccine-mediated protective immunity. However, the role of CD4 T cells seemed more evident in the presence of low-antibody responses. This study provides preclinical data further supporting the use of the adjuvanted 4C-Staph vaccines against S. aureus diseases, and provides critical insights on the correlates of protective immunity necessary to combat this pathogen.
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http://dx.doi.org/10.3389/fimmu.2015.00439DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4561515PMC
October 2015

Expression and Characterization of Recombinant, Tetrameric and Enzymatically Active Influenza Neuraminidase for the Setup of an Enzyme-Linked Lectin-Based Assay.

PLoS One 2015 17;10(8):e0135474. Epub 2015 Aug 17.

Research Center, Novartis Vaccines and Diagnostics s.r.l., (a GSK Company), Siena, Italy.

Developing a universal influenza vaccine that induces broad spectrum and longer-term immunity has become an important potentially achievable target in influenza vaccine research and development. Hemagglutinin (HA) and neuraminidase (NA) are the two major influenza virus antigens. Although antibody responses against influenza virus are mainly directed toward HA, NA is reported to be more genetically stable; hence NA-based vaccines have the potential to be effective for longer time periods. NA-specific immunity has been shown to limit the spread of influenza virus, thus reducing disease symptoms and providing cross-protection against heterosubtypic viruses in mouse challenge experiments. The production of large quantities of highly pure and stable NA could be beneficial for the development of new antivirals, subunit-based vaccines, and novel diagnostic tools. In this study, recombinant NA (rNA) was produced in mammalian cells at high levels from both swine A/California/07/2009 (H1N1) and avian A/turkey/Turkey/01/2005 (H5N1) influenza viruses. Biochemical, structural, and immunological characterizations revealed that the soluble rNAs produced are tetrameric, enzymatically active and immunogenic, and finally they represent good alternatives to conventionally used sources of NA in the Enzyme-Linked Lectin Assay (ELLA).
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0135474PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4539205PMC
May 2016

An Innovative Pseudotypes-Based Enzyme-Linked Lectin Assay for the Measurement of Functional Anti-Neuraminidase Antibodies.

PLoS One 2015 12;10(8):e0135383. Epub 2015 Aug 12.

GSK, Research Center, Via Fiorentina 1, 53100, Siena, Italy; GSK, Peter Merian Strasse, 4056, Basel, Switzerland.

Antibodies (Ab) to neuraminidase (NA) play a role in limiting influenza infection and might help reduce the disease impact. The most widely used serological assay to measure functional anti-NA immune responses is the Enzyme-Linked Lectin Assay (ELLA) which relies on hemagglutinin (HA) mismatched virus reassortants, or detergent treated viruses as the NA source to overcome interference associated with steric hindrance of anti-HA Ab present in sera. The difficulty in producing and handling these reagents, which are not easily adapted for screening large numbers of samples, limits the routine analysis of functional anti-NA Ab in clinical trials. In this study, we produced influenza lentiviral pseudoparticles (PPs) containing only the NA antigen (NA-PPs) with a simple two-plasmid co-transfection system. NA-PPs were characterized and tested as an innovative source of NA in the NA inhibition (NI) assay. Both swine A/California/07/2009 (H1N1) and avian A/turkey/Turkey/01/2005 (H5N1) N1s within NA-PPs retained their sialidase activity and were specifically inhibited by homologous and N1 subtype-specific, heterologous sheep sera. Moreover, A/California/07/2009 N1-PPs were a better source of NA compared to whole live and detergent treated H1N1 viruses in ELLA, likely due to lack of interference by anti-HA Ab, and absence of possible structural modifications caused by treatment with detergent. This innovative assay is safer and applicable to all NAs. Taken together, these results highlight the potential of NA-PPs-based NI assays to be developed as sensitive, flexible, easy to handle and scalable serological tests for routine NA immune response analysis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0135383PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4534301PMC
May 2016

B Cells and Functional Antibody Responses to Combat Influenza.

Front Immunol 2015 30;6:336. Epub 2015 Jun 30.

Research Center, Novartis Vaccines and Diagnostics S.r.l. (a GSK Company) , Siena , Italy.

Vaccination against influenza is the most effective way to protect the population. Current vaccines provide protection by stimulating functional B- and T-cell responses; however, they are poorly immunogenic in particular segments of the population and need to be reformulated almost every year due to the genetic instability of the virus. Next-generation influenza vaccines should be designed to induce cross-reactivity, confer protection against pandemic outbreaks, and promote long-lasting immune responses among individuals at higher risk of infection. Multiple strategies are being developed for the induction of broad functional humoral immunity, including the use of adjuvants, heterologous prime-boost strategies, and epitope-based antigen design. The basic approach is to mimic natural responses to influenza virus infection by promoting cross-reactive neutralizing antibodies that directly prevent the infection. This review provides an overview of the mechanisms underlying humoral responses to influenza vaccination or natural infection, and discusses promising strategies to control influenza virus.
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http://dx.doi.org/10.3389/fimmu.2015.00336DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4485180PMC
July 2015

Oil-in-Water Emulsion MF59 Increases Germinal Center B Cell Differentiation and Persistence in Response to Vaccination.

J Immunol 2015 Aug 13;195(4):1617-27. Epub 2015 Jul 13.

Research Center, Novartis Vaccines and Diagnostics, 53100 Siena, Italy; and

Induction of persistent protective immune responses is a key attribute of a successful vaccine formulation. MF59 adjuvant, an oil-in-water emulsion used in human vaccines, is known to induce persistent high-affinity functional Ab titers and memory B cells, but how it really shapes the Ag-specific B cell compartment is poorly documented. In this study, we characterized the Ab- and Ag-specific B cell compartment in wild-type mice immunized with HlaH35L, a Staphylococcus aureus Ag known to induce measurable functional Ab responses, formulated with MF59 or aluminum salts, focusing on germinal centers (GC) in secondary lymphoid organs. Taking advantage of single-cell flow cytometry analyses, HlaH35L-specific B cells were characterized for the expression of CD38 and GL-7, markers of memory and GC, respectively, and for CD80 and CD73 activation markers. We demonstrated that immunization with MF59-, but not aluminum salt-adjuvanted HlaH35L, induced expanded Ag-specific CD73(+)CD80(-) GC B cells in proximal- and distal-draining lymph nodes, and promoted the persistence of GC B cells, detected up to 4 mo after immunization. In addition to increasing GC B cells, MF59-adjuvanted HlaH35L also increased the frequency of T follicular helper cells. This work extends previous knowledge regarding adaptive immune responses to MF59-adjuvanted vaccines, and, to our knowledge, for the first time an adjuvant used in human licensed products is shown to promote strong and persistent Ag-specific GC responses that might benefit the rational design of new vaccination strategies.
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http://dx.doi.org/10.4049/jimmunol.1402604DOI Listing
August 2015

Innate Response Activator (IRA) B Cells Reside in Human Tonsils and Internalize Bacteria In Vitro.

PLoS One 2015 12;10(6):e0129879. Epub 2015 Jun 12.

Novartis Vaccines and Diagnostics (a GSK company), Research Center, Via Fiorentina 1, Siena, Italy.

Innate response activator (IRA) B cells have been described in mice as a subset of B-1a B cells that produce granulocyte/macrophage colony-stimulating factor (GM-CSF) and have been found in the spleen upon activation. In humans, identification, tissue localization and functionality of these lymphocytes are poorly understood. We hypothesized that IRA B cells could reside in human palatine tonsils, which are a first line of defense from infection of the upper respiratory tract. In the present work, we used flow cytometry and confocal microscopy to identify and characterize human IRA (hIRA) B cells in tonsils. We show that CD19⁺CD20⁺GM-CSF⁺ B cells are present in the tonsils of all the subjects studied at a frequency ranging between ~0.2% and ~0.4% of the conventional CD19⁺CD20⁺GM-CSF⁻ B cells. These cells reside within the B cell follicles, are mostly IgM⁺IgD⁺, express CD5 and show phagocytic activity. Our results support a role for hIRA B cells in the effector immune response to infections in tonsils.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0129879PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4466315PMC
April 2016

Gaps in knowledge and prospects for research of adjuvanted vaccines.

Vaccine 2015 Jun;33 Suppl 2:B40-3

Novartis Vaccines, Via Fiorentina 1, Siena, Italy.

A panel of researchers working in different areas of adjuvanted vaccines deliberated over the topic, "Gaps in knowledge and prospects for research of adjuvanted vaccines" at, "Enhancing Vaccine Immunity and Value" conference held in July 2014. Several vaccine challenges and applications for new adjuvant technologies were discussed.
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http://dx.doi.org/10.1016/j.vaccine.2015.03.057DOI Listing
June 2015

Four-component Staphylococcus aureus vaccine 4C-staph enhances Fcγ receptor expression in neutrophils and monocytes and mitigates S. aureus infection in neutropenic mice.

Infect Immun 2015 Aug 26;83(8):3157-63. Epub 2015 May 26.

Novartis Vaccines and Diagnostics, s.r.l., a GSK Company, Siena, Italy

Staphylococcus aureus is a human bacterial pathogen causing a variety of diseases. The occurrence of multidrug-resistant strains of Staphylococcus aureus underlines the need for a vaccine. Defining immune correlates of protection may support the design of an effective vaccine. We used a murine Staphylococcus aureus infection model, in which bacteria were inoculated in an air pouch generated on the back of the animal. Analysis of the air-pouch content in mice immunized or not with an adjuvanted multiantigen vaccine formulation, four-component S. aureus vaccine (4C-Staph), prior to infection allowed us to measure bacteria, cytokines, and 4C-Staph-specific antibodies and to analyze host immune cells recruited to the infection site. Immunization with 4C-Staph resulted in accumulation of antigen-specific antibodies in the pouch and mitigated the infection. Neutrophils were the most abundant cells in the pouch, and they showed the upregulation of Fcγ receptor (FcγR) following immunization with 4C-Staph. Reduction of the infection was also obtained in mice immunized with 4C-Staph and depleted of neutrophils; these mice showed an increase in monocytes and macrophages. Upregulation of the FcγR and the presence of antigen-specific antibodies induced by immunization with 4C-Staph may contribute to increase bacterial opsonophagocytosis. Protection in neutropenic mice indicated that an effective vaccine could activate alternative protection mechanisms compensating for neutropenia, a condition often occurring in S. aureus-infected patients.
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http://dx.doi.org/10.1128/IAI.00258-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4496606PMC
August 2015

Phagocyte subsets and lymphocyte clonal deletion behind ineffective immune response to Staphylococcus aureus.

FEMS Microbiol Rev 2015 Sep 19;39(5):750-63. Epub 2015 May 19.

Novartis Vaccines, Research Center, via Fiorentina 1, 53100 Siena, Italy

Lack of known mechanisms of protection against Staphylococcus aureus in humans is hindering development of efficacious vaccines. Preclinical as well as clinical data suggest that antibodies play an important role against S. aureus. For instance, certain hypogammaglobulinaemic patients are at increased risk of staphylococcal infections. However, development of effective humoral response may be dampened by converging immune-evasion mechanisms of S. aureus. We hypothesize that B-cell proliferation induced by staphylococcal protein A (SpA) and continuous antigen exposure, without the proper T-cell help and cytokine stimuli, leads to antigen-activated B-cell deletion and anergy. Recent findings suggest an important role of type I neutrophils (PMN-I) and conventionally activated macrophages (M1) against S. aureus, while alternatively activated macrophages (M2) favour biofilm persistence and sepsis. In addition, neutrophil-macrophage cooperation promotes extravasation and activation of neutrophils as well as clearance of bacteria ensnared in neutrophil extracellular traps. Activation of these processes is modulated by cytokines and T cells. Indeed, low CD4(+) T-cell counts represent an important risk factor for skin infections and bacteraemia in patients. Altogether, these observations could lead to the identification of predictive correlates of protection and ways for shifting the balance of the response to the benefit of the host through vaccination.
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http://dx.doi.org/10.1093/femsre/fuv024DOI Listing
September 2015

Vaccine composition formulated with a novel TLR7-dependent adjuvant induces high and broad protection against Staphylococcus aureus.

Proc Natl Acad Sci U S A 2015 Mar 9;112(12):3680-5. Epub 2015 Mar 9.

Novartis Vaccines Research Center, 53100 Siena, Italy;

Both active and passive immunization strategies against Staphylococcus aureus have thus far failed to show efficacy in humans. With the attempt to develop an effective S. aureus vaccine, we selected five conserved antigens known to have different roles in S. aureus pathogenesis. They include the secreted factors α-hemolysin (Hla), ess extracellular A (EsxA), and ess extracellular B (EsxB) and the two surface proteins ferric hydroxamate uptake D2 and conserved staphylococcal antigen 1A. The combined vaccine antigens formulated with aluminum hydroxide induced antibodies with opsonophagocytic and functional activities and provided consistent protection in four mouse models when challenged with a panel of epidemiologically relevant S. aureus strains. The importance of antibodies in protection was demonstrated by passive transfer experiments. Furthermore, when formulated with a toll-like receptor 7-dependent (TLR7) agonist recently designed and developed in our laboratories (SMIP.7-10) adsorbed to alum, the five antigens provided close to 100% protection against four different staphylococcal strains. The new formulation induced not only high antibody titers but also a Th1 skewed immune response as judged by antibody isotype and cytokine profiles. In addition, low frequencies of IL-17-secreting T cells were also observed. Altogether, our data demonstrate that the rational selection of mixtures of conserved antigens combined with Th1/Th17 adjuvants can lead to promising vaccine formulations against S. aureus.
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http://dx.doi.org/10.1073/pnas.1424924112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4378396PMC
March 2015

Evaluating the efficiency of isotope transmission for improved panel design and a comparison of the detection sensitivities of mass cytometer instruments.

Cytometry A 2015 Apr 20;87(4):357-68. Epub 2015 Feb 20.

CEA, Division of Immuno-Virology, IDMIT Center, Institute for Emerging Diseases and Innovative Therapies (iMETI), DSV, Fontenay-aux-Roses, France; Université Paris-Sud, UMR E1, Orsay, France; Vaccine Research Institute (VRI), Créteil, France.

The recent introduction of mass cytometry, a technique coupling a cell introduction system generating a stream of single cells with mass spectrometry, has greatly increased the number of parameters that can be measured per single cell. As with all new technology there is a need for dissemination of standardization and quality control procedures. Here, we characterize variations in sensitivity observed across the mass range of a mass cytometer, using different lanthanide tags. We observed a five-fold difference in lanthanide detection over the mass range and demonstrated that each instrument has its own sensitivity pattern. Therefore, the selection of lanthanide combinations is a key step in the establishment of a staining panel for mass cytometry-based experiments, particularly for multicenter studies. We propose the sensitivity pattern as the basis for panel design, instrument standardization and future implementation of normalization algorithms.
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http://dx.doi.org/10.1002/cyto.a.22648DOI Listing
April 2015

Unleashing the potential of NOD- and Toll-like agonists as vaccine adjuvants.

Proc Natl Acad Sci U S A 2014 Aug 18;111(34):12294-9. Epub 2014 Aug 18.

Novartis Vaccines and Diagnostics, 53100 Siena, Italy.

Innate immunity confers an immediate nonspecific mechanism of microbial recognition through germ line-encoded pattern recognition receptors (PRRs). Of these, Toll-like receptors (TLRs) and nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) have shaped our current understanding of innate regulation of adaptive immunity. It is now recognized that PRRs are paramount in instructing an appropriate adaptive immune response. Their ligands have been the focus of adjuvant research with the goal of generating modern vaccine combinations tailored to specific pathogens. In this review we will highlight the recent findings in the field of adjuvant research with a particular focus on the potential of TLR and NLR ligands as adjuvants and their influence on adaptive immune responses.
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http://dx.doi.org/10.1073/pnas.1400478111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4151741PMC
August 2014

Sublingual immunization with a subunit influenza vaccine elicits comparable systemic immune response as intramuscular immunization, but also induces local IgA and TH17 responses.

Vaccine 2014 Apr 13;32(20):2382-8. Epub 2014 Jan 13.

Vaccines Research, Novartis Vaccines, Siena, Italy.

Influenza is a vaccine-preventable disease that remains a major health problem world-wide. Needle and syringe are still the primary delivery devices, and injection of liquid vaccine into the muscle is still the primary route of immunization. Vaccines could be more convenient and effective if they were delivered by the mucosal route. Elicitation of systemic and mucosal innate and adaptive immune responses, such as pathogen neutralizing antibodies (including mucosal IgA at the site of pathogen entry) and CD4(+) T-helper cells (especially the Th17 subset), have a critical role in vaccine-mediated protection. In the current study, a sublingual subunit influenza vaccine formulated with or without mucosal adjuvant was evaluated for systemic and mucosal immunogenicity and compared to intranasal and intramuscular vaccination. Sublingual administration of adjuvanted influenza vaccine elicited comparable antibody titers to those elicited by intramuscular immunization with conventional influenza vaccine. Furthermore, influenza-specific Th17 cells or neutralizing mucosal IgA were detected exclusively after mucosal immunization.
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http://dx.doi.org/10.1016/j.vaccine.2013.12.043DOI Listing
April 2014

Protection against tuberculosis with homologous or heterologous protein/vector vaccine approaches is not dependent on CD8+ T cells.

J Immunol 2013 Sep 31;191(5):2514-2525. Epub 2013 Jul 31.

Infectious Disease Research Institute, 1616 Eastlake Avenue East, Suite 400, Seattle, WA, USA 98102.

Considerable effort has been directed to develop Mycobacterium tuberculosis vaccines to boost bacille Calmette-Guérin or for those who cannot be immunized with bacille Calmette-Guérin. We hypothesized that CD4(+) and CD8(+) T cell responses with a heterologous prime/boost vaccine approach could induce long-lived vaccine efficacy against M. tuberculosis in C57BL/6 mice. We produced an adenovirus vector expressing ID93 (Ad5-ID93) for induction of CD8 T cells to use with our candidate tuberculosis vaccine, ID93/glucopyranosyl lipid adjuvant (GLA)-stable emulsion (SE), which induces potent Th1 CD4 T cells. Ad5-ID93 generates ID93-specific CD8(+) T cell responses and induces protection against M. tuberculosis. When Ad5-ID93 is administered in a prime-boost strategy with ID93/GLA-SE, both CD4(+) and CD8(+) T cells are generated and provide protection against M. tuberculosis. In a MHC class I-deficient mouse model, all groups including the Ad5-ID93 group elicited an Ag-specific CD4(+) T cell response and significantly fewer Ag-specific CD8(+) T cells, but were still protected against M. tuberculosis, suggesting that CD4(+) Th1 T cells could compensate for the loss of CD8(+) T cells. Lastly, the order of the heterologous immunizations was critical. Long-lived vaccine protection was observed only when Ad5-ID93 was given as the boost following an ID93/GLA-SE prime. The homologous ID93/GLA-SE prime/boost regimen also induced long-lived protection. One of the correlates of protection between these two approaches was an increase in the total number of ID93-specific IFN-γ-producing CD4(+) T cells 6 mo following the last immunization. Our findings provide insight into the development of vaccines not only for tuberculosis, but other diseases requiring T cell immunity.
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http://dx.doi.org/10.4049/jimmunol.1301161DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3791622PMC
September 2013

Rapidly produced SAM(®) vaccine against H7N9 influenza is immunogenic in mice.

Emerg Microbes Infect 2013 Aug 14;2(8):e52. Epub 2013 Aug 14.

Novartis Vaccines and Diagnostics , Cambridge, MA 02139, USA.

The timing of vaccine availability is essential for an effective response to pandemic influenza. In 2009, vaccine became available after the disease peak, and this has motivated the development of next generation vaccine technologies for more rapid responses. The SAM(®) vaccine platform, now in pre-clinical development, is based on a synthetic, self-amplifying mRNA, delivered by a synthetic lipid nanoparticle (LNP). When used to express seasonal influenza hemagglutinin (HA), a SAM vaccine elicited potent immune responses, comparable to those elicited by a licensed influenza subunit vaccine preparation. When the sequences coding for the HA and neuraminidase (NA) genes from the H7N9 influenza outbreak in China were posted on a web-based data sharing system, the combination of rapid and accurate cell-free gene synthesis and SAM vaccine technology allowed the generation of a vaccine candidate in 8 days. Two weeks after the first immunization, mice had measurable hemagglutinin inhibition (HI) and neutralizing antibody titers against the new virus. Two weeks after the second immunization, all mice had HI titers considered protective. If the SAM vaccine platform proves safe, potent, well tolerated and effective in humans, fully synthetic vaccine technologies could provide unparalleled speed of response to stem the initial wave of influenza outbreaks, allowing first availability of a vaccine candidate days after the discovery of a new virus.
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http://dx.doi.org/10.1038/emi.2013.54DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3821287PMC
August 2013

The adjuvant effect of MF59 is due to the oil-in-water emulsion formulation, none of the individual components induce a comparable adjuvant effect.

Vaccine 2013 Jul 16;31(33):3363-9. Epub 2013 May 16.

Novartis Vaccines and Diagnostics Research Center, Via Fiorentina 1, I-53100 Siena, Italy.

MF59 is a safe and effective vaccine adjuvant that has been used in a licensed seasonal influenza vaccine for 15 years. The purpose of the present studies was to directly address a question that has been asked of us on many occasions: "which is the adjuvant active component of MF59?". Since we have recently gained a number of insights on how MF59 works as an adjuvant, we were able to use these approaches to evaluate if the individual components of MF59 (squalene oil, the surfactants Span 85 and Tween 80 or the citrate buffer) showed any direct immunostimulatory activity. We assessed the ability of the individual components to stimulate the innate and adaptive immune responses that we have shown to be indicative of MF59-mediated adjuvanticity. No immune stimulatory capacities could be attributed to squalene, Tween 80 or the citrate buffer alone. Instead, we found that the lipophilic surfactant Span 85 contributes to activation of the muscle transcriptome. However, despite this local activation, Span 85 alone - like the other single components of MF59 - is not sufficient to induce an adjuvant effect. Only the fully formulated MF59 emulsion induces all the established hallmarks of innate and adaptive immune activation, which includes activation of genes indicative of transendothelial cell migration, strong influx of immune cells into the injection site and their enhanced antigen uptake and transport to the lymph nodes. These observations may have important implications in the design of optimal emulsion-based vaccine adjuvants.
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http://dx.doi.org/10.1016/j.vaccine.2013.05.007DOI Listing
July 2013

Evaluation of recombinant Leishmania polyprotein plus glucopyranosyl lipid A stable emulsion vaccines against sand fly-transmitted Leishmania major in C57BL/6 mice.

J Immunol 2012 Nov 8;189(10):4832-41. Epub 2012 Oct 8.

Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

Numerous experimental Leishmania vaccines have been developed to prevent the visceral and cutaneous forms of Leishmaniasis, which occur after exposure to the bite of an infected sand fly, yet only one is under evaluation in humans. KSAC and L110f, recombinant Leishmania polyproteins delivered in a stable emulsion (SE) with the TLR4 agonists monophosphoryl lipid A or glucopyranosyl lipid A (GLA) have shown protection in animal models. KSAC+GLA-SE protected against cutaneous disease following sand fly transmission of Leishmania major in susceptible BALB/c mice. Similar polyprotein adjuvant combinations are the vaccine candidates most likely to see clinical evaluation. We assessed immunity generated by KSAC or L110f vaccination with GLA-SE following challenge with L. major by needle or infected sand fly bite in resistant C57BL/6 mice. Polyprotein-vaccinated mice had a 60-fold increase in CD4(+)IFN-γ(+) T cell numbers versus control animals at 2 wk post-needle inoculation of L. major, and this correlated with a 100-fold reduction in parasite load. Immunity did not, however, reach levels observed in mice with a healed primary infection. Following challenge by infected sand fly bite, polyprotein-vaccinated animals had comparable parasite loads, greater numbers of neutrophils at the challenge site, and reduced CD4(+)IFN-γ(+)/IL-17(+) ratios versus nonvaccinated controls. In contrast, healed animals had significantly reduced parasite loads and higher CD4(+)IFN-γ(+)/IL-17(+) ratios. These observations demonstrate that vaccine-induced protection against needle challenge does not necessarily translate to protection following challenge by infected sand fly bite.
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http://dx.doi.org/10.4049/jimmunol.1201676DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3596879PMC
November 2012