HLA class I binding 9mer peptides from influenza A virus induce CD4 T cell responses.
BACKGROUND
Identification of human leukocyte antigen class I (HLA-I) restricted cytotoxic T cell (CTL) epitopes from influenza virus is of importance for the development of new effective peptide-based vaccines.


RESULTS
In the present work, bioinformatics was used to predict 9mer peptides derived from available influenza A viral proteins with binding affinity for at least one of the 12 HLA-I supertypes. The predicted peptides were then selected in a way that ensured maximal coverage of the available influenza A strains. One hundred and thirty one peptides were synthesized and their binding affinities for the HLA-I supertypes were measured in a biochemical assay. Influenza-specific T cell responses towards the peptides were quantified using IFNgamma ELISPOT assays with peripheral blood mononuclear cells (PBMC) from adult healthy HLA-I typed donors as responder cells. Of the 131 peptides, 21 were found to induce T cell responses in 19 donors. In the ELISPOT assay, five peptides induced responses that could be totally blocked by the pan-specific anti-HLA-I antibody W6/32, whereas 15 peptides induced responses that could be completely blocked in the presence of the pan-specific anti-HLA class II (HLA-II) antibody IVA12. Blocking of HLA-II subtype reactivity revealed that 8 and 6 peptide responses were blocked by anti-HLA-DR and -DP antibodies, respectively. Peptide reactivity of PBMC depleted of CD4(+) or CD8(+) T cells prior to the ELISPOT culture revealed that effectors are either CD4(+) (the majority of reactivities) or CD8(+) T cells, never a mixture of these subsets. Three of the peptides, recognized by CD4(+) T cells showed binding to recombinant DRA1*0101/DRB1*0401 or DRA1*0101/DRB5*0101 molecules in a recently developed biochemical assay.


CONCLUSIONS
HLA-I binding 9mer influenza virus-derived peptides induce in many cases CD4(+) T cell responses restricted by HLA-II molecules.
Wang
Mingjun
M
Department of International Health, Immunology and Microbiology, Faculty of Heath Sciences, University of Copenhagen, Copenhagen, Denmark.
Larsen
Mette V
MV
Nielsen
Morten
M
Harndahl
Mikkel
M
Justesen
Sune
S
Dziegiel
Morten H
MH
Buus
Søren
S
Tang
Sheila T
ST
Lund
Ole
O
Claesson
Mogens H
MH
D000328:Adult; D000368:Aged; D019138:Antibodies, Blocking / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000821:virology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D006684:HLA-DR Antigens / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology; D006801:Humans; D009980:Influenza A virus / Q000276:immunology*; D007371:Interferon-gamma / Q000276:immunology; D008212:Lymphocyte Depletion; D008875:Middle Aged; D010455:Peptides / Q000276:immunology*; D011485:Protein Binding / Q000276:immunology; D015203:Reproducibility of Results; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000821:virology; D014019:Tissue Donors
D019138:Antibodies, Blocking; D000939:Epitopes; D006684:HLA-DR Antigens; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D010455:Peptides; D007371:Interferon-gamma