Structural modeling of the Influenza virus Hemagglutinin protein in complex with a broadly neutralizing antibody

SummaryBroadly neutralizing antibodies against influenza virus hemagglutinin (HA) have the potential to provide universal protection against influenza virus infections. Here, we report a distinct class of broadly neutralizing antibodies targeting an epitope toward the bottom of the HA stalk domain where HA is “anchored” to the viral membrane. Antibodies targeting this membrane-proximal anchor epitope utilized a highly restricted repertoire, which encode for two conserved motifs responsible for HA binding. Anchor targeting B cells were common in the human memory B cell repertoire across subjects, indicating pre-existing immunity against this epitope. Antibodies against the anchor epitope at both the serological and monoclonal antibody levels were potently induced in humans by a chimeric HA vaccine, a potential universal influenza virus vaccine. Altogether, this study reveals an underappreciated class of broadly neutralizing antibodies against H1-expressing viruses that can be robustly recalled by a candidate universal influenza virus vaccine.

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Expression of H5N1 influenza virus hemagglutinin protein fused with protein transduction domain in an alphavirus replicon system

Journal of Virological Methods ◽

10.1016/j.jviromet.2009.07.012 ◽

2010 ◽

Vol 163 (1) ◽

pp. 31-39 ◽

Cited By ~ 1

Author(s):

Shi-gui Yang ◽

Jian-er Wo ◽

Min-wei Li ◽

Fen-fang Mi ◽

Cheng-bo Yu ◽

...

Keyword(s):

Influenza Virus ◽

Protein Transduction ◽

Protein Transduction Domain ◽

H5n1 Influenza Virus ◽

H5n1 Influenza ◽

Influenza Virus Hemagglutinin ◽

Hemagglutinin Protein

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Immunostimulating reconstituted influenza virosome; comprises influenza virus hemagglutinin protein and preferably a hepatitis A virus antigen, for use as vaccine

Vaccine ◽

10.1016/0264-410x(93)90322-o ◽

1993 ◽

Vol 11 (6) ◽

pp. 687

Keyword(s):

Influenza Virus ◽

Hepatitis A ◽

Hepatitis A Virus ◽

Virus Antigen ◽

Influenza Virus Hemagglutinin ◽

Hemagglutinin Protein

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Unmasking Stem-Specific Neutralizing Epitopes by Abolishing N-Linked Glycosylation Sites of Influenza Virus Hemagglutinin Proteins for Vaccine Design

Journal of Virology ◽

10.1128/jvi.00880-16 ◽

2016 ◽

Vol 90 (19) ◽

pp. 8496-8508 ◽

Cited By ~ 23

Author(s):

Wen-Chun Liu ◽

Jia-Tsrong Jan ◽

Yun-Ju Huang ◽

Ting-Hsuan Chen ◽

Suh-Chin Wu

Keyword(s):

Influenza Virus ◽

Neutralizing Antibody ◽

Influenza Vaccines ◽

Mutant Proteins ◽

Fusion Inhibition ◽

Influenza Virus Hemagglutinin ◽

Glycosylation Sites ◽

Antibody Titers ◽

Virus Strains ◽

Globular Head

ABSTRACTInfluenza virus hemagglutinin (HA) protein consists of two components, i.e., a globular head region and a stem region that are folded within six disulfide bonds, plus several N-linked glycans that produce a homotrimeric complex structure. While N-linked glycosylation sites on the globular head are variable among different strains and different subtypes, N-linked glycosylation sites in the stem region are mostly well conserved among various influenza virus strains. Targeting highly conserved HA stem regions has been proposed as a useful strategy for designing universal influenza vaccines. Since the HA stem region is constituted by an HA1 N-terminal part and a full HA2 part, we expressed a series of recombinant HA mutant proteins with deleted N-linked glycosylation sites in the HA1 stem and HA2 stem regions of H5N1 and pH1N1 viruses. Unmasking N-glycans in the HA2 stem region (H5 N484A and H1 N503A) was found to elicit more potent neutralizing antibody titers against homologous, heterologous, and heterosubtypic viruses. Unmasking the HA2 stem N-glycans of H5HA but not H1HA resulted in more CR6261-like and FI6v3-like antibodies and also correlated with the increase of cell fusion inhibition activity in antisera. Only H5 N484A HA2 stem mutant protein immunization increased the numbers of antibody-secreting cells, germinal center B cells, and memory B cells targeting the stem helix A epitopes in splenocytes. Unmasking the HA2 stem N-glycans of H5HA mutant proteins showed a significantly improvement in the protection against homologous virus challenges but did so to a less degree for the protection against heterosubtypic pH1N1 virus challenges. These results may provide useful information for designing more effective influenza vaccines.IMPORTANCEN-linked glycosylation sites in the stem regions of influenza virus hemagglutinin (HA) proteins are mostly well conserved among various influenza virus strains. Targeting highly conserved HA stem regions has been proposed as a useful strategy for designing universal influenza vaccines. Our studies indicate that unmasking the HA2 stem N-glycans of recombinant HA proteins from H5N1 and pH1N1 viruses induced more potent neutralizing antibody titers against homologous and heterosubtypic viruses. However, only immunization with the H5N1 HA2 stem mutant protein can refocus B antibody responses to the helix A epitope for inducing more CR6261-like/FI6v3-like and fusion inhibition antibodies in antisera, resulting in a significant improvement for the protection against lethal H5N1 virus challenges. These results may provide useful information for designing more effective influenza vaccines.

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Antivirals Targeting the Surface Glycoproteins of Influenza Virus: Mechanisms of Action and Resistance

Viruses ◽

10.3390/v13040624 ◽

2021 ◽

Vol 13 (4) ◽

pp. 624

Author(s):

Yaqin Bai ◽

Jeremy C. Jones ◽

Sook-San Wong ◽

Mark Zanin

Keyword(s):

Influenza Virus ◽

Influenza A ◽

Mechanisms Of Action ◽

Antiviral Drugs ◽

Influenza Viruses ◽

High Threshold ◽

Influenza Virus Hemagglutinin ◽

Hemagglutinin Protein ◽

Viral Lifecycle ◽

Emergence Of Resistance

Hemagglutinin and neuraminidase, which constitute the glycoprotein spikes expressed on the surface of influenza A and B viruses, are the most exposed parts of the virus and play critical roles in the viral lifecycle. As such, they make prominent targets for the immune response and antiviral drugs. Neuraminidase inhibitors, particularly oseltamivir, constitute the most commonly used antivirals against influenza viruses, and they have proved their clinical utility against seasonal and emerging influenza viruses. However, the emergence of resistant strains remains a constant threat and consideration. Antivirals targeting the hemagglutinin protein are relatively new and have yet to gain global use but are proving to be effective additions to the antiviral repertoire, with a relatively high threshold for the emergence of resistance. Here we review antiviral drugs, both approved for clinical use and under investigation, that target the influenza virus hemagglutinin and neuraminidase proteins, focusing on their mechanisms of action and the emergence of resistance to them.

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Yeast-Derived Avian Influenza Virus Hemagglutinin Protein Induced Immune Response in SPF Chicken

Journal of Animal and Veterinary Advances ◽

10.3923/javaa.2011.999.1002 ◽

2011 ◽

Vol 10 (8) ◽

pp. 999-1002

Author(s):

Hongzhuan Wu ◽

Karyn Scissum-Gu ◽

Narendra K. Singh ◽

Shan-Chia Ou ◽

Joseph J. Giambrone

Keyword(s):

Immune Response ◽

Influenza Virus ◽

Avian Influenza ◽

Avian Influenza Virus ◽

Influenza Virus Hemagglutinin ◽

Hemagglutinin Protein

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Stability of the Influenza Virus Hemagglutinin Protein Correlates with Evolutionary Dynamics

mSphere ◽

10.1128/mspheredirect.00554-17 ◽

2018 ◽

Vol 3 (1) ◽

Cited By ~ 9

Author(s):

Eili Y. Klein ◽

Deena Blumenkrantz ◽

Adrian Serohijos ◽

Eugene Shakhnovich ◽

Jeong-Mo Choi ◽

...

Keyword(s):

Influenza Virus ◽

Protein Stability ◽

Evolutionary Dynamics ◽

Immune Escape ◽

Antigenic Site ◽

Viral Fitness ◽

Influenza Virus Hemagglutinin ◽

Hemagglutinin Protein ◽

Ha Protein ◽

The Impact

ABSTRACTProtein thermodynamics are an integral determinant of viral fitness and one of the major drivers of protein evolution. Mutations in the influenza A virus (IAV) hemagglutinin (HA) protein can eliminate neutralizing antibody binding to mediate escape from preexisting antiviral immunity. Prior research on the IAV nucleoprotein suggests that protein stability may constrain seasonal IAV evolution; however, the role of stability in shaping the evolutionary dynamics of the HA protein has not been explored. We used the full coding sequence of 9,797 H1N1pdm09 HA sequences and 16,716 human seasonal H3N2 HA sequences to computationally estimate relative changes in the thermal stability of the HA protein between 2009 and 2016. Phylogenetic methods were used to characterize how stability differences impacted the evolutionary dynamics of the virus. We found that pandemic H1N1 IAV strains split into two lineages that had different relative HA protein stabilities and that later variants were descended from the higher-stability lineage. Analysis of the mutations associated with the selective sweep of the higher-stability lineage found that they were characterized by the early appearance of highly stabilizing mutations, the earliest of which was not located in a known antigenic site. Experimental evidence further suggested that H1N1 HA stability may be correlated within vitrovirus production and infection. A similar analysis of H3N2 strains found that surviving lineages were also largely descended from viruses predicted to encode more-stable HA proteins. Our results suggest that HA protein stability likely plays a significant role in the persistence of different IAV lineages.IMPORTANCEOne of the constraints on fast-evolving viruses, such as influenza virus, is protein stability, or how strongly the folded protein holds together. Despite the importance of this protein property, there has been limited investigation of the impact of the stability of the influenza virus hemagglutinin protein—the primary antibody target of the immune system—on its evolution. Using a combination of computational estimates of stability and experiments, our analysis found that viruses with more-stable hemagglutinin proteins were associated with long-term persistence in the population. There are two potential reasons for the observed persistence. One is that more-stable proteins tolerate destabilizing mutations that less-stable proteins could not, thus increasing opportunities for immune escape. The second is that greater stability increases the fitness of the virus through increased production of infectious particles. Further research on the relative importance of these mechanisms could help inform the annual influenza vaccine composition decision process.

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