1
|
Zhou F, Hansen L, Pedersen G, Grødeland G, Cox R. Matrix M Adjuvanted H5N1 Vaccine Elicits Broadly Neutralizing Antibodies and Neuraminidase Inhibiting Antibodies in Humans That Correlate With In Vivo Protection. Front Immunol 2021; 12:747774. [PMID: 34887855 PMCID: PMC8650010 DOI: 10.3389/fimmu.2021.747774] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 11/05/2021] [Indexed: 11/13/2022] Open
Abstract
The highly pathogenic avian influenza H5N1 viruses constantly evolve and give rise to novel variants that have caused widespread zoonotic outbreaks and sporadic human infections. Therefore, vaccines capable of eliciting broadly protective antibody responses are desired and under development. We here investigated the magnitude, kinetics and protective efficacy of the multi-faceted humoral immunity induced by vaccination in healthy adult volunteers with a Matrix M adjuvanted virosomal H5N1 vaccine. Vaccinees were given escalating doses of adjuvanted vaccine (1.5μg, 7.5μg, or 30μg), or a non-adjuvanted vaccine (30μg). An evaluation of sera from vaccinees against pseudotyped viruses covering all (sub)clades isolated from human H5N1 infections demonstrated that the adjuvanted vaccines (7.5μg and 30μg) could elicit rapid and robust increases of broadly cross-neutralizing antibodies against all clades. In addition, the adjuvanted vaccines also induced multifaceted antibody responses including hemagglutinin stalk domain specific, neuraminidase inhibiting, and antibody-dependent cellular cytotoxicity inducing antibodies. The lower adjuvanted dose (1.5µg) showed delayed kinetics, whilst the non-adjuvanted vaccine induced overall lower levels of antibody responses. Importantly, we demonstrate that human sera post vaccination with the adjuvanted (30μg) vaccine provided full protection against a lethal homologous virus challenge in mice. Of note, when combining our data from mice and humans we identified the neutralizing and neuraminidase inhibiting antibody titers as correlates of in vivo protection.
Collapse
Affiliation(s)
- Fan Zhou
- Influenza Center, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Lena Hansen
- Influenza Center, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Gabriel Pedersen
- Influenza Center, Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Vaccine Research, Statens Serum Institut, Copenhagen, Denmark
| | - Gunnveig Grødeland
- Department of Immunology, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Rebecca Cox
- Influenza Center, Department of Clinical Science, University of Bergen, Bergen, Norway.,Department of Microbiology, Haukeland University Hospital, Bergen, Norway
| |
Collapse
|
2
|
Li Z, Zhao Y, Li Y, Chen X. Adjuvantation of Influenza Vaccines to Induce Cross-Protective Immunity. Vaccines (Basel) 2021; 9:75. [PMID: 33494477 PMCID: PMC7911902 DOI: 10.3390/vaccines9020075] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 12/22/2022] Open
Abstract
Influenza poses a huge threat to global public health. Influenza vaccines are the most effective and cost-effective means to control influenza. Current influenza vaccines mainly induce neutralizing antibodies against highly variable globular head of hemagglutinin and lack cross-protection. Vaccine adjuvants have been approved to enhance seasonal influenza vaccine efficacy in the elderly and spare influenza vaccine doses. Clinical studies found that MF59 and AS03-adjuvanted influenza vaccines could induce cross-protective immunity against non-vaccine viral strains. In addition to MF59 and AS03 adjuvants, experimental adjuvants, such as Toll-like receptor agonists, saponin-based adjuvants, cholera toxin and heat-labile enterotoxin-based mucosal adjuvants, and physical adjuvants, are also able to broaden influenza vaccine-induced immune responses against non-vaccine strains. This review focuses on introducing the various types of adjuvants capable of assisting current influenza vaccines to induce cross-protective immunity in preclinical and clinical studies. Mechanisms of licensed MF59 and AS03 adjuvants to induce cross-protective immunity are also introduced. Vaccine adjuvants hold a great promise to adjuvant influenza vaccines to induce cross-protective immunity.
Collapse
Affiliation(s)
| | | | | | - Xinyuan Chen
- Biomedical & Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, 7 Greenhouse Road, Avedisian Hall, Room 480, Kingston, RI 02881, USA; (Z.L.); (Y.Z.); (Y.L.)
| |
Collapse
|
3
|
Haveri A, Ikonen N, Savolainen-Kopra C, Julkunen I. Long-lasting heterologous antibody responses after sequential vaccination with A/Indonesia/5/2005 and A/Vietnam/1203/2004 pre-pandemic influenza A(H5N1) virus vaccines. Vaccine 2020; 39:402-411. [PMID: 33246672 DOI: 10.1016/j.vaccine.2020.11.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 11/04/2020] [Accepted: 11/13/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Avian influenza A(H5N1) viruses have caused sporadic infections in humans and thus they pose a significant global health threat. Among symptomatic patients the case fatality rate has been ca. 50%. H5N1 viruses exist in multiple clades and subclades and several candidate vaccines have been developed to prevent A(H5N1) infection as a principal measure for preventing the disease. METHODS Serum antibodies against various influenza A(H5N1) clade viruses were measured in adults by ELISA-based microneutralization and haemagglutination inhibition tests before and after vaccination with two different A(H5N1) vaccines in 2009 and 2011. RESULTS Two doses of AS03-adjuvanted A/Indonesia/5/2005 vaccine induced good homologous but poor heterologous neutralizing antibody responses against different clade viruses. However, non-adjuvanted A/Vietnam/1203/2004 booster vaccination in 2011 induced very strong and long-lasting homologous and heterologous antibody responses while homologous response remained weak in naïve subjects. CONCLUSIONS Sequential vaccination with two different A(H5N1) pre-pandemic vaccines induced long-lasting high level cross-clade immunity against influenza A(H5N1) strains, thus supporting a prime-boost vaccination strategy in pandemic preparedness plans.
Collapse
Affiliation(s)
- Anu Haveri
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare (THL), POB 30, 00271 Helsinki, Finland.
| | - Niina Ikonen
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare (THL), POB 30, 00271 Helsinki, Finland
| | - Carita Savolainen-Kopra
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare (THL), POB 30, 00271 Helsinki, Finland
| | - Ilkka Julkunen
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare (THL), POB 30, 00271 Helsinki, Finland; Institute of Biomedicine, University of Turku and Turku University Hospital, Kiinamyllynkatu 10, 20520 Turku, Finland
| |
Collapse
|
4
|
Davis CW, Jackson KJL, McCausland MM, Darce J, Chang C, Linderman SL, Chennareddy C, Gerkin R, Brown SJ, Wrammert J, Mehta AK, Cheung WC, Boyd SD, Waller EK, Ahmed R. Influenza vaccine-induced human bone marrow plasma cells decline within a year after vaccination. Science 2020; 370:237-241. [PMID: 32792465 PMCID: PMC10155619 DOI: 10.1126/science.aaz8432] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 08/02/2020] [Indexed: 01/09/2023]
Abstract
A universal vaccine against influenza would ideally generate protective immune responses that are not only broadly reactive against multiple influenza strains but also long-lasting. Because long-term serum antibody levels are maintained by bone marrow plasma cells (BMPCs), we investigated the production and maintenance of these cells after influenza vaccination. We found increased numbers of influenza-specific BMPCs 4 weeks after immunization with the seasonal inactivated influenza vaccine, but numbers returned to near their prevaccination levels after 1 year. This decline was driven by the loss of BMPCs induced by the vaccine, whereas preexisting BMPCs were maintained. Our results suggest that most BMPCs generated by influenza vaccination in adults are short-lived. Designing strategies to enhance their persistence will be a key challenge for the next generation of influenza vaccines.
Collapse
Affiliation(s)
- Carl W Davis
- Emory Vaccine Center and Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA.,Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA
| | | | - Megan M McCausland
- Emory Vaccine Center and Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA.,Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA
| | - Jaime Darce
- Cell Signaling Technology, Inc., Danvers, MA, USA
| | - Cathy Chang
- Emory Vaccine Center and Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA.,Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA
| | - Susanne L Linderman
- Emory Vaccine Center and Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA.,Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA
| | - Chakravarthy Chennareddy
- Emory Vaccine Center and Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA.,Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA
| | - Rebecca Gerkin
- Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA.,Department of Hematology and Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
| | - Shantoria J Brown
- Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA.,Department of Hematology and Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
| | - Jens Wrammert
- Emory Vaccine Center and Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA.,Department of Pediatrics, Division of Infectious Disease, Emory University School of Medicine, Atlanta, GA, USA
| | - Aneesh K Mehta
- Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA.,Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA, USA
| | | | - Scott D Boyd
- Department of Pathology, Stanford University, Stanford, CA, USA
| | - Edmund K Waller
- Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA.,Department of Hematology and Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
| | - Rafi Ahmed
- Emory Vaccine Center and Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA. .,Emory-UGA Center of Excellence of Influenza Research and Surveillance (CEIRS), Atlanta GA, USA
| |
Collapse
|
5
|
Recombinant H5 hemagglutinin adjuvanted with nanoemulsion protects ferrets against pathogenic avian influenza virus challenge. Vaccine 2019; 37:1591-1600. [DOI: 10.1016/j.vaccine.2019.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/31/2019] [Accepted: 02/02/2019] [Indexed: 12/29/2022]
|
6
|
Weinberger B. Adjuvant strategies to improve vaccination of the elderly population. Curr Opin Pharmacol 2018; 41:34-41. [PMID: 29677646 DOI: 10.1016/j.coph.2018.03.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 03/30/2018] [Indexed: 10/17/2022]
Abstract
Immunosenescence contributes to increased incidence and severity of many infections in old age and is responsible for impaired immunogenicity and efficacy of vaccines. Adjuvants are one strategy to enhance immunogenicity of vaccines. The oil-in-water emulsions MF59TM and AS03, as well as a virosomal vaccine have been licensed in seasonal or pandemic influenza vaccines and are/were used successfully in the elderly. AS01, a liposome-based adjuvant comprising two immunostimulants has recently been approved in a recombinant protein vaccine for older adults, which showed very high efficacy against herpes zoster in clinical trials. Several adjuvants for use in the older population are in clinical and preclinical development and will hopefully improve vaccines for this age group in the future.
Collapse
Affiliation(s)
- Birgit Weinberger
- Institute for Biomedical Aging Research, Universität Innsbruck, Innsbruck, Austria.
| |
Collapse
|
7
|
Abstract
In spite of current influenza vaccines being immunogenic, evolution of the influenza virus can reduce efficacy and so influenza remains a major threat to public health. One approach to improve influenza vaccines is to include adjuvants; substances that boost the immune response. Adjuvants are particularly beneficial for influenza vaccines administered during a pandemic when a rapid response is required or for use in patients with impaired immune responses, such as infants and the elderly. This review outlines the current use of adjuvants in human influenza vaccines, including what they are, why they are used and what is known of their mechanism of action. To date, six adjuvants have been used in licensed human vaccines: Alum, MF59, AS03, AF03, virosomes and heat labile enterotoxin (LT). In general these adjuvants are safe and well tolerated, but there have been some rare adverse events when adjuvanted vaccines are used at a population level that may discourage the inclusion of adjuvants in influenza vaccines, for example the association of LT with Bell's Palsy. Improved understanding about the mechanisms of the immune response to vaccination and infection has led to advances in adjuvant technology and we describe the experimental adjuvants that have been tested in clinical trials for influenza but have not yet progressed to licensure. Adjuvants alone are not sufficient to improve influenza vaccine efficacy because they do not address the underlying problem of mismatches between circulating virus and the vaccine. However, they may contribute to improved efficacy of next-generation influenza vaccines and will most likely play a role in the development of effective universal influenza vaccines, though what that role will be remains to be seen.
Collapse
Affiliation(s)
- John S Tregoning
- a Mucosal Infection and Immunity group, Section of Virology, Department of Medicine , St Mary's Campus, Imperial College London , UK
| | - Ryan F Russell
- a Mucosal Infection and Immunity group, Section of Virology, Department of Medicine , St Mary's Campus, Imperial College London , UK
| | - Ekaterina Kinnear
- a Mucosal Infection and Immunity group, Section of Virology, Department of Medicine , St Mary's Campus, Imperial College London , UK
| |
Collapse
|
8
|
Papadopoulos NG, Megremis S, Kitsioulis NA, Vangelatou O, West P, Xepapadaki P. Promising approaches for the treatment and prevention of viral respiratory illnesses. J Allergy Clin Immunol 2017; 140:921-932. [PMID: 28739285 PMCID: PMC7112313 DOI: 10.1016/j.jaci.2017.07.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 07/11/2017] [Accepted: 07/14/2017] [Indexed: 02/09/2023]
Abstract
Viral respiratory tract infections are the most common human ailments, leading to enormous health and economic burden. Hundreds of viral species and subtypes have been associated with these conditions, with influenza viruses, respiratory syncytial virus, and rhinoviruses being the most frequent and with the highest burden. When considering prevention or treatment of viral respiratory tract infections, potential targets include the causative pathogens themselves but also the immune response, disease transmission, or even just the symptoms. Strategies targeting all these aspects are developing concurrently, and several novel and promising approaches are emerging. In this perspective we overview the entire range of options and highlight some of the most promising approaches, including new antiviral agents, symptomatic or immunomodulatory drugs, the re-emergence of natural remedies, and vaccines and public health policies toward prevention. Wide-scale prevention through immunization appears to be within reach for respiratory syncytial virus and promising for influenza virus, whereas additional effort is needed in regard to rhinovirus, as well as other respiratory tract viruses.
Collapse
Affiliation(s)
- Nikolaos G Papadopoulos
- Division of Infection, Immunity & Respiratory Medicine, University of Manchester, Manchester, United Kingdom; Allergy Department, 2nd Pediatric Clinic, National & Kapodistrian University of Athens, Athens, Greece.
| | - Spyridon Megremis
- Division of Infection, Immunity & Respiratory Medicine, University of Manchester, Manchester, United Kingdom
| | - Nikolaos A Kitsioulis
- Allergy Department, 2nd Pediatric Clinic, National & Kapodistrian University of Athens, Athens, Greece
| | - Olympia Vangelatou
- Department of Nutritional Physiology & Feeding, Agricultural University of Athens, Athens, Greece
| | - Peter West
- Division of Infection, Immunity & Respiratory Medicine, University of Manchester, Manchester, United Kingdom
| | - Paraskevi Xepapadaki
- Allergy Department, 2nd Pediatric Clinic, National & Kapodistrian University of Athens, Athens, Greece
| |
Collapse
|
9
|
Venkatraman N, Anagnostou N, Bliss C, Bowyer G, Wright D, Lövgren-Bengtsson K, Roberts R, Poulton I, Lawrie A, Ewer K, V S Hill A. Safety and immunogenicity of heterologous prime-boost immunization with viral-vectored malaria vaccines adjuvanted with Matrix-M™. Vaccine 2017; 35:6208-6217. [PMID: 28941620 DOI: 10.1016/j.vaccine.2017.09.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/09/2017] [Accepted: 09/07/2017] [Indexed: 12/19/2022]
Abstract
The use of viral vectors in heterologous prime-boost regimens to induce potent T cell responses in addition to humoral immunity is a promising vaccination strategy in the fight against malaria. We conducted an open-label, first-in-human, controlled Phase I study evaluating the safety and immunogenicity of Matrix-M adjuvanted vaccination with a chimpanzee adenovirus serotype 63 (ChAd63) prime followed by a modified vaccinia Ankara (MVA) boost eight weeks later, both encoding the malaria ME-TRAP antigenic sequence (a multiple epitope string fused to thrombospondin-related adhesion protein). Twenty-two healthy adults were vaccinated intramuscularly with either ChAd63-MVA ME-TRAP alone (n=6) or adjuvanted with 25μg (n=8) or 50μg (n=8) Matrix-M. Vaccinations appeared to be safe and generally well tolerated, with the majority of local and systemic adverse events being mild in nature. The addition of Matrix-M to the vaccine did not increase local reactogenicity; however, systemic adverse events were reported more frequently by volunteers who received adjuvanted vaccine in comparison to the control group. T cell ELISpot responses peaked at 7-days post boost vaccination with MVA ME-TRAP in all three groups. TRAP-specific IgG responses were highest at 28-days post boost with MVA ME-TRAP in all three groups. There were no differences in cellular and humoral immunogenicity at any of the time points between the control group and the adjuvanted groups. We demonstrate that Matrix-M can be safely used in combination with ChAd63-MVA ME-TRAP heterologous prime-boost immunization without any reduction in cellular or humoral immunogenicity. Clinical Trials Registration NCT01669512.
Collapse
Affiliation(s)
- Navin Venkatraman
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK; Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Old Road, Headington, Oxford OX3 7LJ, United Kingdom.
| | - Nicholas Anagnostou
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK; Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Old Road, Headington, Oxford OX3 7LJ, United Kingdom
| | - Carly Bliss
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK
| | - Georgina Bowyer
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK
| | - Danny Wright
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK
| | | | - Rachel Roberts
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK; Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Old Road, Headington, Oxford OX3 7LJ, United Kingdom
| | - Ian Poulton
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK; Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Old Road, Headington, Oxford OX3 7LJ, United Kingdom
| | - Alison Lawrie
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK; Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Old Road, Headington, Oxford OX3 7LJ, United Kingdom
| | - Katie Ewer
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK
| | - Adrian V S Hill
- Jenner Institute, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford OX3 7DQ, UK
| |
Collapse
|
10
|
Adjuvant activity of saponins from Kazakhstani plants on the immune responses to subunit influenza vaccine. Arch Virol 2017; 162:3817-3826. [DOI: 10.1007/s00705-017-3560-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/24/2017] [Indexed: 01/10/2023]
|
11
|
Influenza Virus Hemagglutinin Stalk-Specific Antibodies in Human Serum are a Surrogate Marker for In Vivo Protection in a Serum Transfer Mouse Challenge Model. mBio 2017; 8:mBio.01463-17. [PMID: 28928215 PMCID: PMC5605943 DOI: 10.1128/mbio.01463-17] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The immunogenicity of current influenza virus vaccines is assessed by measuring an increase of influenza virus-specific antibodies in a hemagglutination inhibition assay. This method exclusively measures antibodies against the hemagglutinin head domain. While this domain is immunodominant, it has been shown that hemagglutination inhibition titers do not always accurately predict protection from disease. In addition, several novel influenza virus vaccines that are currently under development do not target the hemagglutinin head domain, but rather more conserved sites, including the hemagglutinin stalk. Importantly, antibodies against the hemagglutinin stalk do not show activity in hemagglutination inhibition assays and will require different methods for quantification. In this study, we tested human serum samples from a seasonal influenza virus vaccination trial and an avian H5N1 virus vaccination trial for antibody activities in multiple types of assays, including binding assays and also functional assays. We then performed serum transfer experiments in mice which then received an H1N1 virus challenge to assess the in vivo protective effects of the antibodies. We found that hemagglutinin-specific antibody levels measured in an enzyme-linked immunosorbent assay (ELISA) correlated well with protection from weight loss in mice. In addition, we found that weight loss was also inversely correlated with the level of serum antibody-dependent cellular cytotoxicity (ADCC) as measured in a reporter assay. These findings indicate that protection is in part conferred by Fc-dependent mechanisms. In conclusion, ELISAs can be used to measure hemagglutinin-specific antibody levels that could serve as a surrogate marker of protection for universal influenza virus vaccines.IMPORTANCE Influenza viruses are a serious concern for public health and cause a large number of deaths worldwide every year. Current influenza virus vaccines can confer protection from disease, but they often show low efficacy due to the ever-changing nature of the viruses. Novel vaccination approaches target conserved epitopes of the virus, including the hemagglutinin stalk domain, to elicit universally protective antibodies that also bind to mutated viruses or new subtypes of viruses. Importantly, the hemagglutination inhibition assay-the only assay that has been accepted as a correlate of protection by regulatory authorities-cannot measure antibodies against the hemagglutinin stalk domain. Therefore, novel correlates of protection and assays to measure vaccine immunogenicity need to be developed. In this study, we correlated the results from multiple assays with protection in mice after transfer of human serum and a lethal virus challenge to investigate potential novel serological surrogate markers for protection.
Collapse
|