Cross-reactive antibodies binding to H4 hemagglutinin protect against a lethal H4N6 influenza virus challenge in the mouse model.
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ABSTRACT:
SUBMITTER: Amanat F
PROVIDER: S-EPMC6455122 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
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Project description:Seasonal vaccines are currently the most effective countermeasure against influenza. However, seasonal vaccines are only effective against strains closely related to the influenza strains contained in the vaccine. Recently a new hemagglutinin (HA) stem-based antigen, the so-called "mini-HA", has been shown to induce a cross-protective immune response in influenza-naive mice and non-human primates (NHP). However, prior exposure to influenza can have a profound effect on the immune response to subsequent influenza infection and the protective efficacy of vaccination. Here we show that mini-HA, compared to a trivalent influenza vaccine (TIV), elicits a broadened influenza-specific humoral immune response in NHP previously exposed to influenza. Serum transfer experiments showed that antibodies induced by both mini-HA and seasonal vaccine protected mice against lethal challenge with a H1N1 influenza strain heterologous to the H1 HA included in the TIV. However, antibodies elicited by mini-HA showed an additional benefit of protecting mice against lethal heterosubtypic H5N1 influenza challenge, associated with H5 HA-specific functional antibodies.
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Project description:The recent outbreak of H7N9 influenza virus infections in humans in China has raised concerns about the pandemic potential of this strain. Here, we test the efficacy of H3 stalk-based chimeric hemagglutinin universal influenza virus vaccine constructs to protect against H7N9 challenge in mice. Chimeric hemagglutinin constructs protected from viral challenge in the context of different administration routes as well as with a generic oil-in-water adjuvant similar to formulations licensed for use in humans.
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Project description:The continued evolution of influenza viruses reduces the effectiveness of vaccination and antiviral drugs. The identification of novel and universal agents for influenza prophylaxis and treatment is an urgent need. We have previously described two potent single-domain antibodies (VHH), G2.3 and H1.2, which bind to the stem domain of hemagglutinin and efficiently neutralize H1N1 and H5N2 influenza viruses in vivo. In this study, we modified these VHHs with Fc-fragment to enhance their antiviral activity. Reformatting of G2.3 into bivalent Fc-fusion molecule increased its in vitro neutralizing activity against H1N1 and H2N3 viruses up to 80-fold and, moreover, resulted in obtaining the ability to neutralize H5N2 and H9N2 subtypes. We demonstrated that a dose as low as 0.6 mg/kg of G2.3-Fc or H1.2-Fc administered systemically or locally before infection could protect mice from lethal challenges with both H1N1 and H5N2 viruses. Furthermore, G2.3-Fc reduced the lung viral load to an undetectable level. Both VHH-Fc antibodies showed in vivo therapeutic efficacy when delivered via systemic or local route. The findings support G2.3-Fc as a potential therapeutic agent for both prophylaxis and therapy of Group 1 influenza A infection.
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Project description:Broadly cross-reactive antibodies (Abs) that recognize conserved epitopes within the influenza virus hemagglutinin (HA) stalk domain are of particular interest for their potential use as therapeutic and prophylactic agents against multiple influenza virus subtypes, including zoonotic virus strains. Here, we characterized four human HA stalk-reactive monoclonal antibodies (MAbs) for their binding breadth and affinity, in vitro neutralization capacity, and in vivo protective potential against an highly pathogenic avian influenza virus. The monoclonal antibodies were isolated from individuals shortly following infection with (70-1F02 and 1009-3B05) or vaccination against (05-2G02 and 09-3A01) A(H1N1)pdm09. Three of the MAbs bound HAs from multiple strains of group 1 viruses, and one MAb, 05-2G02, bound to both group 1 and group 2 influenza A virus HAs. All four antibodies prophylactically protected mice against a lethal challenge with the highly pathogenic A/Vietnam/1203/04 (H5N1) strain. Two MAbs, 70-1F02 and 09-3A01, were further tested for their therapeutic efficacy against the same strain and showed good efficacy in this setting as well. One MAb, 70-1F02, cocrystallized with H5 HA and showed heavy-chain-only interactions similar to those seen with the previously described CR6261 anti-stalk antibody. Finally, we show that antibodies that compete with these MAbs are prevalent in serum from an individual recently infected with the A(H1N1)pdm09 virus. The antibodies described here can be developed into broad-spectrum antiviral therapeutics that could be used to combat infections by zoonotic or emerging pandemic influenza viruses.IMPORTANCE The rise in zoonotic infections of humans by emerging influenza viruses is a worldwide public health concern. The majority of recent zoonotic human influenza cases were caused by H7N9 and H5Nx viruses and were associated with high morbidity and mortality. In addition, seasonal influenza viruses are estimated to cause up to 650,000 deaths annually worldwide. Currently available antiviral treatment options include only neuraminidase inhibitors, but some influenza viruses are naturally resistant to these drugs, and others quickly develop resistance-conferring mutations. Alternative therapeutics are urgently needed. Broadly protective antibodies that target the conserved "stalk" domain of the hemagglutinin represent potential potent antiviral prophylactic and therapeutic agents that can assist pandemic preparedness. Here, we describe four human monoclonal antibodies that target conserved regions of influenza HA and characterize their binding spectrum as well as their protective capacity in prophylactic and therapeutic settings against a lethal challenge with a zoonotic influenza virus.
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Project description:The increased worldwide awareness of seasonal and pandemic influenza, including pandemic H1N1 virus, has stimulated interest in the development of economic platforms for rapid, large-scale production of safe and effective subunit vaccines. In recent years, plants have demonstrated their utility as such a platform and have been used to produce vaccine antigens against various infectious diseases. Previously, we have produced in our transient plant expression system a recombinant monomeric hemagglutinin (HA) protein (HAC1) derived from A/California/04/09 (H1N1) strain of influenza virus and demonstrated its immunogenicity and safety in animal models and human volunteers. In the current study, to mimic the authentic HA structure presented on the virus surface and to improve stability and immunogenicity of the HA antigen, we generated trimeric HA by introducing a trimerization motif from a heterologous protein into the HA sequence. Here, we describe the engineering, production in Nicotiana benthamiana plants, and characterization of the highly purified recombinant trimeric HA protein (tHA-BC) from A/California/04/09 (H1N1) strain of influenza virus. The results demonstrate the induction of serum hemagglutination inhibition antibodies by tHA-BC and its protective efficacy in mice against a lethal viral challenge. In addition, the immunogenic and protective doses of tHA-BC were much lower compared with monomeric HAC1. Further investigation into the optimum vaccine dose and/or regimen as well as the stability of trimerized HA is necessary to determine whether trimeric HA is a more potent vaccine antigen than monomeric HA.
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Project description:The ebolaviruses cause severe and rapidly progressing hemorrhagic fever. There are five ebolavirus species; although much is known about Zaire ebolavirus (EBOV) and its neutralization by antibodies, little is known about Sudan ebolavirus (SUDV), which is emerging with increasing frequency. Here we describe monoclonal antibodies containing a human framework that potently inhibit infection by SUDV and protect mice from lethal challenge. The murine antibody 16F6, which binds the SUDV envelope glycoprotein (GP), served as the starting point for design. Sequence and structural alignment revealed similarities between 16F6 and YADS1, a synthetic antibody with a humanized scaffold. A focused phage library was constructed and screened to impart 16F6-like recognition properties onto the YADS1 scaffold. A panel of 17 antibodies were characterized and found to have a range of neutralization potentials against a pseudotype virus infection model. Neutralization correlated with GP binding as determined by ELISA. Two of these clones, E10 and F4, potently inhibited authentic SUDV and conferred protection and memory immunity in mice from lethal SUDV challenge. E10 and F4 were further shown to bind to the same epitope on GP as 16F6 with comparable affinities. These antibodies represent strong immunotherapeutic candidates for treatment of SUDV infection.
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Project description:The hemagglutinin protein (HA) on the surface of influenza virus is essential for viral entry into the host cells. The HA1 subunit of HA is also the primary target for neutralizing antibodies. The HA2 subunit is less exposed on the virion surface and more conserved than HA1. We have previously designed an HA2-based immunogen derived from the sequence of the H3N2 A/HK/68 virus. In the present study, we report the design of an HA2-based immunogen from the H1N1 subtype (PR/8/34). This immunogen (H1HA0HA6) and its circular permutant (H1HA6) were well folded and provided complete protection against homologous viral challenge. Antisera of immunized mice showed cross-reactivity with HA proteins of different strains and subtypes. Although no neutralization was observable in a conventional neutralization assay, sera of immunized guinea pigs competed with a broadly neutralizing antibody, CR6261, for binding to recombinant Viet/04 HA protein, suggesting that CR6261-like antibodies were elicited by the immunogens. Stem domain immunogens from a seasonal H1N1 strain (A/NC/20/99) and a recent pandemic strain (A/Cal/07/09) provided cross-protection against A/PR/8/34 viral challenge. HA2-containing stem domain immunogens therefore have the potential to provide subtype-specific protection.
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Project description:Influenza B virus (IBV) circulates in the human population and causes considerable disease burden worldwide, each year. Current IBV vaccines can struggle to mount an effective cross-reactive immune response, as strains become mismatched, due to constant antigenic changes. Additional strategies which use monoclonal antibodies, with broad reactivity, are of considerable interest, both, as diagnostics and as immunotherapeutics. Alternatives to conventional monoclonal antibodies, such as single domain antibodies (NanobodiesTM) with well-documented advantages for applications in infectious disease, have been emerging. In this study we have isolated single domain antibodies (sdAbs), specific to IBV, using alpacas immunised with recombinant hemagglutinin (HA) from two representative viruses, B/Florida/04/2006 (B/Yamagata lineage) and B/Brisbane/60/2008 (B/Victoria lineage). Using phage display, we have isolated a panel of single domain antibodies (sdAbs), with both cross-reactive and lineage-specific binding. Several sdAbs recognise whole virus antigens, corresponding to influenza B strains included in vaccines spanning over 20 years, and were capable of neutralising IBV pseudotypes corresponding to prototype strains from both lineages. Lineage-specific sdAbs recognised the head domain, whereas, sdAbs identified as cross-reactive could be classified as either head binding or stem binding. Using yeast display, we were able to correlate lineage specificity with naturally occurring sequence divergence, at residue 122 in the highly variable 120 loop of the HA1 domain. The single domain antibodies described, might have applications in IBV diagnostics, vaccine potency testing and as immunotherapeutics.
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Project description:Influenza viruses remain a major global public health risk. In addition to seasonal influenza viruses, epizootic influenza A H7 subtype viruses of both the Asian and North American lineage are of concern due to their pandemic potential. In China, the simultaneous occurrence of H7N9 zoonotic episodes and seasonal influenza virus epidemics could potentially lead to novel reassortant viruses with the ability to efficiently spread among humans. Recently, the H7N9 virus has evolved into two new lineages, the Pearl River Delta and the Yangtze River Delta clade. This development has also resulted in viruses with a polybasic cleavage site in the hemagglutinin that are highly pathogenic in avian species and have caused human infections. In addition, an outbreak of a highly pathogenic H7N8 strain was reported in the US state of Indiana in 2016. Furthermore, an H7N2 feline virus strain caused an outbreak in cats in an animal shelter in New York City in 2016, resulting in one human zoonotic event. In this study, mouse monoclonal antibodies previously raised against the hemagglutinin of the A/Shanghai/1/2013 (H7N9) virus were tested for their (cross-) reactivity to these novel H7 viruses. Moreover, the functionality of these antibodies was assessed in vitro in hemagglutination inhibition and microneutralization assays. The therapeutic and prophylactic efficacy of the broadly reactive antibodies against novel H7 viruses was determined in vivo in mouse passive transfer-viral challenge experiments. Our results provide data about the conservation of critical H7 epitopes and could inform the selection of pre-pandemic H7 vaccine strains.
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