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MVA vectors expressing conserved influenza proteins protect mice against lethal challenge with H5N1, H9N2 and H7N1 viruses.

Hessel A, Savidis-Dacho H, Coulibaly S, Portsmouth D, Kreil TR, Crowe BA, Schwendinger MG, Pilz A, Barrett PN, Falkner FG, Schäfer B - PLoS ONE (2014)

Bottom Line: Pre-exposure to H1N1pdm09 increased protective efficacy against lethal H5N1 challenge.NP-expressing vectors induced high numbers of influenza-specific CD4(+) and CD8(+) T cells and high titer influenza-specific antibody responses.Higher influenza-specific CD4(+) T cell responses and NP-specific CD8(+) T cell responses were associated with increased protective efficacy.

View Article: PubMed Central - PubMed

Affiliation: Vaccine R&D, Baxter Bioscience, Orth/Donau, Austria.

ABSTRACT

Background: The availability of a universal influenza vaccine able to induce broad cross-reactive immune responses against diverse influenza viruses would provide an alternative to currently available strain-specific vaccines. We evaluated the ability of vectors based on modified vaccinia virus Ankara (MVA) expressing conserved influenza proteins to protect mice against lethal challenge with multiple influenza subtypes.

Methods: Mice were immunized with MVA vectors expressing H5N1-derived nucleoprotein (NP), the stem region of hemagglutinin (HA), matrix proteins 1 and 2 (M1 and M2), the viral polymerase basic protein 1 (PB1), or the HA stem fused to a quadrivalent matrix protein 2 extracellular domain (M2e). Immunized mice were challenged with lethal doses of H5N1, H7N1 or H9N2 virus and monitored for disease symptoms and weight loss. To investigate the influence of previous exposure to influenza virus on protective immune responses induced by conserved influenza proteins, mice were infected with pandemic H1N1 virus (H1N1pdm09) prior to immunization and subsequently challenged with H5N1 virus. Antibody and T cell responses were assessed by ELISA and flow cytometry, respectively.

Results: MVA vectors expressing NP alone, or co-expressed with other conserved influenza proteins, protected mice against lethal challenge with H5N1, H7N1 or H9N2 virus. Pre-exposure to H1N1pdm09 increased protective efficacy against lethal H5N1 challenge. None of the other conserved influenza proteins provided significant levels of protection against lethal challenge. NP-expressing vectors induced high numbers of influenza-specific CD4(+) and CD8(+) T cells and high titer influenza-specific antibody responses. Higher influenza-specific CD4(+) T cell responses and NP-specific CD8(+) T cell responses were associated with increased protective efficacy.

Conclusions: MVA vectors expressing influenza NP protect mice against lethal challenge with H5N1, H7N1 and H9N2 viruses by a mechanism involving influenza-specific CD4(+) and CD8(+) T cell responses.

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Antibody and T cell responses.(A) ELISA titers against whole-virus H5N1. The starting dilution of the assay is 1∶100. (B) Percentage of CD4+ T cells reacting to whole-virus H5N1, H1N1 and H9N2 and to recombinant H5 hemagglutinin (rHA H5) antigen after immunization of mice with MVA vectors. (C) Percentage of CD8+ T cells reacting to HA and NP peptides. Asterisks denote statistical significance calculated by two-way ANOVA and Bonferroni posttests (*p<0.01, **p<0.001, ***p<0.0001).
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pone-0088340-g004: Antibody and T cell responses.(A) ELISA titers against whole-virus H5N1. The starting dilution of the assay is 1∶100. (B) Percentage of CD4+ T cells reacting to whole-virus H5N1, H1N1 and H9N2 and to recombinant H5 hemagglutinin (rHA H5) antigen after immunization of mice with MVA vectors. (C) Percentage of CD8+ T cells reacting to HA and NP peptides. Asterisks denote statistical significance calculated by two-way ANOVA and Bonferroni posttests (*p<0.01, **p<0.001, ***p<0.0001).

Mentions: The ability of MVA-expressed conserved influenza proteins to induce influenza-specific antibodies was evaluated by ELISA in sera collected three weeks after the second immunization, using whole H5N1 antigen (Figure 4A). Titers >1000 were induced by MVA-NP, and substantially and significantly higher titers (>10,000, p<0.001) were induced by vectors co-expressing NP and HA stem or NP and HA stem/M2e. In contrast, much lower antibody titers were induced by HA stem or HA stem/M2e in the absence of NP, and no detectable antibodies were found to be induced against M1- or M2-expressing vectors.


MVA vectors expressing conserved influenza proteins protect mice against lethal challenge with H5N1, H9N2 and H7N1 viruses.

Hessel A, Savidis-Dacho H, Coulibaly S, Portsmouth D, Kreil TR, Crowe BA, Schwendinger MG, Pilz A, Barrett PN, Falkner FG, Schäfer B - PLoS ONE (2014)

Antibody and T cell responses.(A) ELISA titers against whole-virus H5N1. The starting dilution of the assay is 1∶100. (B) Percentage of CD4+ T cells reacting to whole-virus H5N1, H1N1 and H9N2 and to recombinant H5 hemagglutinin (rHA H5) antigen after immunization of mice with MVA vectors. (C) Percentage of CD8+ T cells reacting to HA and NP peptides. Asterisks denote statistical significance calculated by two-way ANOVA and Bonferroni posttests (*p<0.01, **p<0.001, ***p<0.0001).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921149&req=5

pone-0088340-g004: Antibody and T cell responses.(A) ELISA titers against whole-virus H5N1. The starting dilution of the assay is 1∶100. (B) Percentage of CD4+ T cells reacting to whole-virus H5N1, H1N1 and H9N2 and to recombinant H5 hemagglutinin (rHA H5) antigen after immunization of mice with MVA vectors. (C) Percentage of CD8+ T cells reacting to HA and NP peptides. Asterisks denote statistical significance calculated by two-way ANOVA and Bonferroni posttests (*p<0.01, **p<0.001, ***p<0.0001).
Mentions: The ability of MVA-expressed conserved influenza proteins to induce influenza-specific antibodies was evaluated by ELISA in sera collected three weeks after the second immunization, using whole H5N1 antigen (Figure 4A). Titers >1000 were induced by MVA-NP, and substantially and significantly higher titers (>10,000, p<0.001) were induced by vectors co-expressing NP and HA stem or NP and HA stem/M2e. In contrast, much lower antibody titers were induced by HA stem or HA stem/M2e in the absence of NP, and no detectable antibodies were found to be induced against M1- or M2-expressing vectors.

Bottom Line: Pre-exposure to H1N1pdm09 increased protective efficacy against lethal H5N1 challenge.NP-expressing vectors induced high numbers of influenza-specific CD4(+) and CD8(+) T cells and high titer influenza-specific antibody responses.Higher influenza-specific CD4(+) T cell responses and NP-specific CD8(+) T cell responses were associated with increased protective efficacy.

View Article: PubMed Central - PubMed

Affiliation: Vaccine R&D, Baxter Bioscience, Orth/Donau, Austria.

ABSTRACT

Background: The availability of a universal influenza vaccine able to induce broad cross-reactive immune responses against diverse influenza viruses would provide an alternative to currently available strain-specific vaccines. We evaluated the ability of vectors based on modified vaccinia virus Ankara (MVA) expressing conserved influenza proteins to protect mice against lethal challenge with multiple influenza subtypes.

Methods: Mice were immunized with MVA vectors expressing H5N1-derived nucleoprotein (NP), the stem region of hemagglutinin (HA), matrix proteins 1 and 2 (M1 and M2), the viral polymerase basic protein 1 (PB1), or the HA stem fused to a quadrivalent matrix protein 2 extracellular domain (M2e). Immunized mice were challenged with lethal doses of H5N1, H7N1 or H9N2 virus and monitored for disease symptoms and weight loss. To investigate the influence of previous exposure to influenza virus on protective immune responses induced by conserved influenza proteins, mice were infected with pandemic H1N1 virus (H1N1pdm09) prior to immunization and subsequently challenged with H5N1 virus. Antibody and T cell responses were assessed by ELISA and flow cytometry, respectively.

Results: MVA vectors expressing NP alone, or co-expressed with other conserved influenza proteins, protected mice against lethal challenge with H5N1, H7N1 or H9N2 virus. Pre-exposure to H1N1pdm09 increased protective efficacy against lethal H5N1 challenge. None of the other conserved influenza proteins provided significant levels of protection against lethal challenge. NP-expressing vectors induced high numbers of influenza-specific CD4(+) and CD8(+) T cells and high titer influenza-specific antibody responses. Higher influenza-specific CD4(+) T cell responses and NP-specific CD8(+) T cell responses were associated with increased protective efficacy.

Conclusions: MVA vectors expressing influenza NP protect mice against lethal challenge with H5N1, H7N1 and H9N2 viruses by a mechanism involving influenza-specific CD4(+) and CD8(+) T cell responses.

Show MeSH
Related in: MedlinePlus