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Globular Head-Displayed Conserved Influenza H1 Hemagglutinin Stalk Epitopes Confer Protection against Heterologous H1N1 Virus.

Klausberger M, Tscheliessnig R, Neff S, Nachbagauer R, Wohlbold TJ, Wilde M, Palmberger D, Krammer F, Jungbauer A, Grabherr R - PLoS ONE (2016)

Bottom Line: Peptide-based vaccines have gained much interest as they allow the immune system to focus on relevant but less immunogenic epitopes.Flow cytometry and competition assays suggest that the identified stalk sequences do not recapitulate the epitopes of already described broadly neutralizing stalk antibodies.Vaccine constructs displaying 25-mer stalk sequences provided up to 75% protection from lethal heterologous virus challenge in BALB/c mice and induced antibody responses against the H1 hemagglutinin.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, University of Natural Resources and Life Sciences Vienna, Vienna, Austria.

ABSTRACT
Significant genetic variability in the head region of the influenza A hemagglutinin, the main target of current vaccines, makes it challenging to develop a long-lived seasonal influenza prophylaxis. Vaccines based on the conserved hemagglutinin stalk domain might provide broader cross-reactive immunity. However, this region of the hemagglutinin is immunosubdominant to the head region. Peptide-based vaccines have gained much interest as they allow the immune system to focus on relevant but less immunogenic epitopes. We developed a novel influenza A hemagglutinin-based display platform for H1 hemagglutinin stalk peptides that we identified in an epitope mapping assay using human immune sera and synthetic HA peptides. Flow cytometry and competition assays suggest that the identified stalk sequences do not recapitulate the epitopes of already described broadly neutralizing stalk antibodies. Vaccine constructs displaying 25-mer stalk sequences provided up to 75% protection from lethal heterologous virus challenge in BALB/c mice and induced antibody responses against the H1 hemagglutinin. The developed platform based on a vaccine antigen has the potential to be either used as stand-alone or as prime-vaccine in combination with conventional seasonal or pandemic vaccines for the amplification of stalk-based cross-reactive immunity in humans or as platform to evaluate the relevance of viral peptides/epitopes for protection against influenza virus infection.

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Related in: MedlinePlus

Schematic of the recombinant HA-based display platform for HA stalk peptides.To improve immunogenicity of an identified H1 subtype HA (red) stalk epitope (indicated by a star) we genetically engineered it into the head domain of a heterologous H3 subtype HA carrier protein (blue) to yield a recombinant protein-based display platform for conserved HA stalk epitopes.
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pone.0153579.g003: Schematic of the recombinant HA-based display platform for HA stalk peptides.To improve immunogenicity of an identified H1 subtype HA (red) stalk epitope (indicated by a star) we genetically engineered it into the head domain of a heterologous H3 subtype HA carrier protein (blue) to yield a recombinant protein-based display platform for conserved HA stalk epitopes.

Mentions: We used an H3 subtype HA (phylogenetic group 2) as carrier protein for the identified H1 subtype-derived stalk peptides (phylogenetic group 1) (Fig 3) and decided not to exceed the verified insertion capacity of the B loop by much more than 5 amino acids. As broadly-neutralizing HA-specific antibodies show a neutralization profile that is largely confined to subtypes from the same phylogenetic group [20], cross-protective immunity from the H3 HA carrier in an in vivo challenge experiment with an A(H1N1) challenge virus or background signal in a serological assay with an H1 HA was not expected. Stalk peptides selected for being displayed on HA carrier proteins are given in Fig 4. Peptides No. 86 and 107 are either located next to or within an identified antigenic peptide stretch (peptides 87–89 and 106–109 respectively), but had no apparent antigenicity in the binding assay (Fig 1A and S1A Fig). Not knowing, whether these peptides, nevertheless, could have any advantageous effects on the antigenicity of these stretches, we included them as this did not exceed our pre-defined insertion capacity of approximately 25 aa. All selected peptides show a high degree of homosubtypic conservation spanning H1 viruses with more than 90 years of drift, covering two pandemic strains from 1918 and 2009 and historical H1 vaccine strains (Fig 4). HA head-displayed peptide-stretch 106–109 had to be withdrawn from further experiments due to very low expression yields (S4 Fig).


Globular Head-Displayed Conserved Influenza H1 Hemagglutinin Stalk Epitopes Confer Protection against Heterologous H1N1 Virus.

Klausberger M, Tscheliessnig R, Neff S, Nachbagauer R, Wohlbold TJ, Wilde M, Palmberger D, Krammer F, Jungbauer A, Grabherr R - PLoS ONE (2016)

Schematic of the recombinant HA-based display platform for HA stalk peptides.To improve immunogenicity of an identified H1 subtype HA (red) stalk epitope (indicated by a star) we genetically engineered it into the head domain of a heterologous H3 subtype HA carrier protein (blue) to yield a recombinant protein-based display platform for conserved HA stalk epitopes.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835069&req=5

pone.0153579.g003: Schematic of the recombinant HA-based display platform for HA stalk peptides.To improve immunogenicity of an identified H1 subtype HA (red) stalk epitope (indicated by a star) we genetically engineered it into the head domain of a heterologous H3 subtype HA carrier protein (blue) to yield a recombinant protein-based display platform for conserved HA stalk epitopes.
Mentions: We used an H3 subtype HA (phylogenetic group 2) as carrier protein for the identified H1 subtype-derived stalk peptides (phylogenetic group 1) (Fig 3) and decided not to exceed the verified insertion capacity of the B loop by much more than 5 amino acids. As broadly-neutralizing HA-specific antibodies show a neutralization profile that is largely confined to subtypes from the same phylogenetic group [20], cross-protective immunity from the H3 HA carrier in an in vivo challenge experiment with an A(H1N1) challenge virus or background signal in a serological assay with an H1 HA was not expected. Stalk peptides selected for being displayed on HA carrier proteins are given in Fig 4. Peptides No. 86 and 107 are either located next to or within an identified antigenic peptide stretch (peptides 87–89 and 106–109 respectively), but had no apparent antigenicity in the binding assay (Fig 1A and S1A Fig). Not knowing, whether these peptides, nevertheless, could have any advantageous effects on the antigenicity of these stretches, we included them as this did not exceed our pre-defined insertion capacity of approximately 25 aa. All selected peptides show a high degree of homosubtypic conservation spanning H1 viruses with more than 90 years of drift, covering two pandemic strains from 1918 and 2009 and historical H1 vaccine strains (Fig 4). HA head-displayed peptide-stretch 106–109 had to be withdrawn from further experiments due to very low expression yields (S4 Fig).

Bottom Line: Peptide-based vaccines have gained much interest as they allow the immune system to focus on relevant but less immunogenic epitopes.Flow cytometry and competition assays suggest that the identified stalk sequences do not recapitulate the epitopes of already described broadly neutralizing stalk antibodies.Vaccine constructs displaying 25-mer stalk sequences provided up to 75% protection from lethal heterologous virus challenge in BALB/c mice and induced antibody responses against the H1 hemagglutinin.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, University of Natural Resources and Life Sciences Vienna, Vienna, Austria.

ABSTRACT
Significant genetic variability in the head region of the influenza A hemagglutinin, the main target of current vaccines, makes it challenging to develop a long-lived seasonal influenza prophylaxis. Vaccines based on the conserved hemagglutinin stalk domain might provide broader cross-reactive immunity. However, this region of the hemagglutinin is immunosubdominant to the head region. Peptide-based vaccines have gained much interest as they allow the immune system to focus on relevant but less immunogenic epitopes. We developed a novel influenza A hemagglutinin-based display platform for H1 hemagglutinin stalk peptides that we identified in an epitope mapping assay using human immune sera and synthetic HA peptides. Flow cytometry and competition assays suggest that the identified stalk sequences do not recapitulate the epitopes of already described broadly neutralizing stalk antibodies. Vaccine constructs displaying 25-mer stalk sequences provided up to 75% protection from lethal heterologous virus challenge in BALB/c mice and induced antibody responses against the H1 hemagglutinin. The developed platform based on a vaccine antigen has the potential to be either used as stand-alone or as prime-vaccine in combination with conventional seasonal or pandemic vaccines for the amplification of stalk-based cross-reactive immunity in humans or as platform to evaluate the relevance of viral peptides/epitopes for protection against influenza virus infection.

Show MeSH
Related in: MedlinePlus