Limits...
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.

Show MeSH

Related in: MedlinePlus

Displayed H1 HA stalk peptides elicit antibodies that bind to the native H1 HA protein but do not strongly compete with anti-stalk mAb KB2.(A) Individual post-vaccination sera were assayed for their reactivity with a recombinant trimeric soluble HA from pandemic CAL09 (H1N1) and (B) were further tested for competition binding to chimeric cH6/1 HA in the presence of 10 μg/mL KB2. Sera were from mice vaccinated with the H3 subtype HIR05 HA (black) or with stalk peptides from a H1 subtype (NC99) virus engineered into its globular head: HIR05/NC99-Ep66-69 (green), HIR05/NC99-Ep86-89 (pink), HIR05/NC99-Ep69+73 (blue) or HIR05/NC99-Ep73+96 (yellow) or from mice vaccinated with the TIV Agriflu® (grey). Due to the lack of enough serum from two mice, there are only three measurements given for vaccine group HIR05/NC99-Ep66-69. * indicates a P value of ≤0.05.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4835069&req=5

pone.0153579.g006: Displayed H1 HA stalk peptides elicit antibodies that bind to the native H1 HA protein but do not strongly compete with anti-stalk mAb KB2.(A) Individual post-vaccination sera were assayed for their reactivity with a recombinant trimeric soluble HA from pandemic CAL09 (H1N1) and (B) were further tested for competition binding to chimeric cH6/1 HA in the presence of 10 μg/mL KB2. Sera were from mice vaccinated with the H3 subtype HIR05 HA (black) or with stalk peptides from a H1 subtype (NC99) virus engineered into its globular head: HIR05/NC99-Ep66-69 (green), HIR05/NC99-Ep86-89 (pink), HIR05/NC99-Ep69+73 (blue) or HIR05/NC99-Ep73+96 (yellow) or from mice vaccinated with the TIV Agriflu® (grey). Due to the lack of enough serum from two mice, there are only three measurements given for vaccine group HIR05/NC99-Ep66-69. * indicates a P value of ≤0.05.

Mentions: To investigate whether immune sera of mice in our study groups contained antibodies that recognise the parental HA protein, we tested them in a serological assay with soluble trimeric CAL09 HA (containing a different trimerisation domain and purification tag as the HA used for immunization). Generally, we saw a trend of 2-fold higher (non-significant) mean endpoint titers in our vaccine groups HIR05/NC99-Ep66-69 and HIR05/NC99-Ep73+96 as compared to the positive control group (Fig 6A). This suggests that vaccination with the displayed stalk peptides successfully induced stalk peptide-specific antibodies that are able to recognise the parental antigen and that our display system may have improved B-cell recognition of the displayed stalk peptides. The highest mean titer was mounted in the group immunized with a displayed putative discontinuous epitope comprising the fusion peptide (HIR05/NC99-Ep69+73), which was 8-fold higher than in the positive control group (1:1,140 vs. 1:9,180 respectively; p = 0.0393) (Fig 6A). None of the mice in this group, however, were protected from morbidity and mortality (Fig 5).


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)

Displayed H1 HA stalk peptides elicit antibodies that bind to the native H1 HA protein but do not strongly compete with anti-stalk mAb KB2.(A) Individual post-vaccination sera were assayed for their reactivity with a recombinant trimeric soluble HA from pandemic CAL09 (H1N1) and (B) were further tested for competition binding to chimeric cH6/1 HA in the presence of 10 μg/mL KB2. Sera were from mice vaccinated with the H3 subtype HIR05 HA (black) or with stalk peptides from a H1 subtype (NC99) virus engineered into its globular head: HIR05/NC99-Ep66-69 (green), HIR05/NC99-Ep86-89 (pink), HIR05/NC99-Ep69+73 (blue) or HIR05/NC99-Ep73+96 (yellow) or from mice vaccinated with the TIV Agriflu® (grey). Due to the lack of enough serum from two mice, there are only three measurements given for vaccine group HIR05/NC99-Ep66-69. * indicates a P value of ≤0.05.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0153579.g006: Displayed H1 HA stalk peptides elicit antibodies that bind to the native H1 HA protein but do not strongly compete with anti-stalk mAb KB2.(A) Individual post-vaccination sera were assayed for their reactivity with a recombinant trimeric soluble HA from pandemic CAL09 (H1N1) and (B) were further tested for competition binding to chimeric cH6/1 HA in the presence of 10 μg/mL KB2. Sera were from mice vaccinated with the H3 subtype HIR05 HA (black) or with stalk peptides from a H1 subtype (NC99) virus engineered into its globular head: HIR05/NC99-Ep66-69 (green), HIR05/NC99-Ep86-89 (pink), HIR05/NC99-Ep69+73 (blue) or HIR05/NC99-Ep73+96 (yellow) or from mice vaccinated with the TIV Agriflu® (grey). Due to the lack of enough serum from two mice, there are only three measurements given for vaccine group HIR05/NC99-Ep66-69. * indicates a P value of ≤0.05.
Mentions: To investigate whether immune sera of mice in our study groups contained antibodies that recognise the parental HA protein, we tested them in a serological assay with soluble trimeric CAL09 HA (containing a different trimerisation domain and purification tag as the HA used for immunization). Generally, we saw a trend of 2-fold higher (non-significant) mean endpoint titers in our vaccine groups HIR05/NC99-Ep66-69 and HIR05/NC99-Ep73+96 as compared to the positive control group (Fig 6A). This suggests that vaccination with the displayed stalk peptides successfully induced stalk peptide-specific antibodies that are able to recognise the parental antigen and that our display system may have improved B-cell recognition of the displayed stalk peptides. The highest mean titer was mounted in the group immunized with a displayed putative discontinuous epitope comprising the fusion peptide (HIR05/NC99-Ep69+73), which was 8-fold higher than in the positive control group (1:1,140 vs. 1:9,180 respectively; p = 0.0393) (Fig 6A). None of the mice in this group, however, were protected from morbidity and mortality (Fig 5).

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