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Conservation and diversity of influenza A H1N1 HLA-restricted T cell epitope candidates for epitope-based vaccines.

Tan PT, Heiny AT, Miotto O, Salmon J, Marques ET, Lemonnier F, August JT - PLoS ONE (2010)

Bottom Line: Immune escape is generally attributed to reduced antibody recognition of the viral hemagglutinin and neuraminidase proteins whose rate of mutation is much greater than that of the internal non-structural proteins.The 54 peptides were compared to the 2007-2009 human H1N1 sequences for selection of sequences in the design of a new candidate H1N1 vaccine, specifically targeted to highly-conserved HLA-restricted T cell epitopes.Seventeen (17) T cell epitopes in PB1, PB2, and M1 were selected as vaccine targets based on sequence conservation over the past 30 years, high functional avidity, non-identity to human peptides, clustered localization, and promiscuity to multiple HLA alleles.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America. ptan4@jhmi.edu

ABSTRACT

Background: The immune-related evolution of influenza viruses is exceedingly complex and current vaccines against influenza must be reformulated for each influenza season because of the high degree of antigenic drift among circulating influenza strains. Delay in vaccine production is a serious problem in responding to a pandemic situation, such as that of the current H1N1 strain. Immune escape is generally attributed to reduced antibody recognition of the viral hemagglutinin and neuraminidase proteins whose rate of mutation is much greater than that of the internal non-structural proteins. As a possible alternative, vaccines directed at T cell epitope domains of internal influenza proteins, that are less susceptible to antigenic variation, have been investigated.

Methodology/principal findings: HLA transgenic mouse strains expressing HLA class I A*0201, A*2402, and B*0702, and class II DRB1*1501, DRB1*0301 and DRB1*0401 were immunized with 196 influenza H1N1 peptides that contained residues of highly conserved proteome sequences of the human H1N1, H3N2, H1N2, H5N1, and avian influenza A strains. Fifty-four (54) peptides that elicited 63 HLA-restricted peptide-specific T cell epitope responses were identified by IFN-gamma ELISpot assay. The 54 peptides were compared to the 2007-2009 human H1N1 sequences for selection of sequences in the design of a new candidate H1N1 vaccine, specifically targeted to highly-conserved HLA-restricted T cell epitopes.

Conclusions/significance: Seventeen (17) T cell epitopes in PB1, PB2, and M1 were selected as vaccine targets based on sequence conservation over the past 30 years, high functional avidity, non-identity to human peptides, clustered localization, and promiscuity to multiple HLA alleles. These candidate vaccine antigen sequences may be applicable to any avian or human influenza A virus.

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Localization of HLA-restricted T cell epitopes of conserved sequences of influenza polymerases, NP, and M1 proteins.Numbers represent aa positions. Highly conserved aa are shown as grey boxes. T cell epitopes were restricted by HLA-DR4 (black boxes), -DR3 (blue boxes), -DR2 (brown boxes), -A24 (green boxes), and -B7 (orange boxes).
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pone-0008754-g001: Localization of HLA-restricted T cell epitopes of conserved sequences of influenza polymerases, NP, and M1 proteins.Numbers represent aa positions. Highly conserved aa are shown as grey boxes. T cell epitopes were restricted by HLA-DR4 (black boxes), -DR3 (blue boxes), -DR2 (brown boxes), -A24 (green boxes), and -B7 (orange boxes).

Mentions: Immunization of the HLA transgenic mice with the 196 H1N1 peptides was carried out with 2 pools of about 100 peptides each, with groups of 9 mice of each transgenic strain. Interferon-γ (IFN-γ) ELISpot assays for HLA-restricted class I and class II responses were performed with splenocytes of the immunized mice that were depleted of CD4+ and CD8+ T cells, respectively, to identify the responding T cell subset. The initial assays contained matrix arrays of peptide pools followed by validation assays with individual peptides [19]. Of the 196 peptides, 54 contained T cell epitopes that elicited 63 ELISpot responses (8 A24, 2 B7, 16 DR2, 17 DR3, and 20 DR4) (Table 1). None of the 196 peptides tested induced T cell responses in mice expressing the HLA-A2 allele. Forty-seven (47) of the 54 epitopes were restricted by one HLA allele; eight by class I HLA-A24 and -B7, and 39 by class II HLA-DR2, -DR3, and -DR4. The remaining 7 peptides contained epitopes that were presented by at least two HLA alleles of distinct supertypes i.e. they contained multiple or promiscuous T cell epitopes. Epitopes of PB1680–696 and PB2548–564 were presented by both HLA class I and II alleles. Sixteen (16) pairs of consecutive peptides were restricted by the same HLA allele, possibly because there were identical epitopes in the overlapping 11 aa sequence shared by the 2 adjacent peptides. Clusters of 2 or more T cell epitopes with at least 16 conserved aa were M1175–197, PB1120–142, 340–374, 489–576, and PB242–64, 126–146 (Table 1, Figure 1).


Conservation and diversity of influenza A H1N1 HLA-restricted T cell epitope candidates for epitope-based vaccines.

Tan PT, Heiny AT, Miotto O, Salmon J, Marques ET, Lemonnier F, August JT - PLoS ONE (2010)

Localization of HLA-restricted T cell epitopes of conserved sequences of influenza polymerases, NP, and M1 proteins.Numbers represent aa positions. Highly conserved aa are shown as grey boxes. T cell epitopes were restricted by HLA-DR4 (black boxes), -DR3 (blue boxes), -DR2 (brown boxes), -A24 (green boxes), and -B7 (orange boxes).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2807450&req=5

pone-0008754-g001: Localization of HLA-restricted T cell epitopes of conserved sequences of influenza polymerases, NP, and M1 proteins.Numbers represent aa positions. Highly conserved aa are shown as grey boxes. T cell epitopes were restricted by HLA-DR4 (black boxes), -DR3 (blue boxes), -DR2 (brown boxes), -A24 (green boxes), and -B7 (orange boxes).
Mentions: Immunization of the HLA transgenic mice with the 196 H1N1 peptides was carried out with 2 pools of about 100 peptides each, with groups of 9 mice of each transgenic strain. Interferon-γ (IFN-γ) ELISpot assays for HLA-restricted class I and class II responses were performed with splenocytes of the immunized mice that were depleted of CD4+ and CD8+ T cells, respectively, to identify the responding T cell subset. The initial assays contained matrix arrays of peptide pools followed by validation assays with individual peptides [19]. Of the 196 peptides, 54 contained T cell epitopes that elicited 63 ELISpot responses (8 A24, 2 B7, 16 DR2, 17 DR3, and 20 DR4) (Table 1). None of the 196 peptides tested induced T cell responses in mice expressing the HLA-A2 allele. Forty-seven (47) of the 54 epitopes were restricted by one HLA allele; eight by class I HLA-A24 and -B7, and 39 by class II HLA-DR2, -DR3, and -DR4. The remaining 7 peptides contained epitopes that were presented by at least two HLA alleles of distinct supertypes i.e. they contained multiple or promiscuous T cell epitopes. Epitopes of PB1680–696 and PB2548–564 were presented by both HLA class I and II alleles. Sixteen (16) pairs of consecutive peptides were restricted by the same HLA allele, possibly because there were identical epitopes in the overlapping 11 aa sequence shared by the 2 adjacent peptides. Clusters of 2 or more T cell epitopes with at least 16 conserved aa were M1175–197, PB1120–142, 340–374, 489–576, and PB242–64, 126–146 (Table 1, Figure 1).

Bottom Line: Immune escape is generally attributed to reduced antibody recognition of the viral hemagglutinin and neuraminidase proteins whose rate of mutation is much greater than that of the internal non-structural proteins.The 54 peptides were compared to the 2007-2009 human H1N1 sequences for selection of sequences in the design of a new candidate H1N1 vaccine, specifically targeted to highly-conserved HLA-restricted T cell epitopes.Seventeen (17) T cell epitopes in PB1, PB2, and M1 were selected as vaccine targets based on sequence conservation over the past 30 years, high functional avidity, non-identity to human peptides, clustered localization, and promiscuity to multiple HLA alleles.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America. ptan4@jhmi.edu

ABSTRACT

Background: The immune-related evolution of influenza viruses is exceedingly complex and current vaccines against influenza must be reformulated for each influenza season because of the high degree of antigenic drift among circulating influenza strains. Delay in vaccine production is a serious problem in responding to a pandemic situation, such as that of the current H1N1 strain. Immune escape is generally attributed to reduced antibody recognition of the viral hemagglutinin and neuraminidase proteins whose rate of mutation is much greater than that of the internal non-structural proteins. As a possible alternative, vaccines directed at T cell epitope domains of internal influenza proteins, that are less susceptible to antigenic variation, have been investigated.

Methodology/principal findings: HLA transgenic mouse strains expressing HLA class I A*0201, A*2402, and B*0702, and class II DRB1*1501, DRB1*0301 and DRB1*0401 were immunized with 196 influenza H1N1 peptides that contained residues of highly conserved proteome sequences of the human H1N1, H3N2, H1N2, H5N1, and avian influenza A strains. Fifty-four (54) peptides that elicited 63 HLA-restricted peptide-specific T cell epitope responses were identified by IFN-gamma ELISpot assay. The 54 peptides were compared to the 2007-2009 human H1N1 sequences for selection of sequences in the design of a new candidate H1N1 vaccine, specifically targeted to highly-conserved HLA-restricted T cell epitopes.

Conclusions/significance: Seventeen (17) T cell epitopes in PB1, PB2, and M1 were selected as vaccine targets based on sequence conservation over the past 30 years, high functional avidity, non-identity to human peptides, clustered localization, and promiscuity to multiple HLA alleles. These candidate vaccine antigen sequences may be applicable to any avian or human influenza A virus.

Show MeSH
Related in: MedlinePlus