Influenza A subtype cross-protection after immunization of outbred mice with a purified chimeric NS1/HA2 influenza virus protein.
Influenza A/PR/8/34-derived chimeric (D) protein (SK&F 106160) composed of the first 81 amino acids (aa) of NS1 fused to the conserved 157 C-terminal aa of HA2 (NS1 1-81-HA2 65-222) was previously shown to induce H-2d-restricted protective cytotoxic T-lymphocyte (CTL) immunity in inbred mice. However, D protein, like other small peptides, exhibited haplotype dependence and was not immunogenic in H-2b and H-2K mice. A potential use of this antigen in humans and the role of T cells in any protection were evaluated in outbred Swiss and inbred CBF6F1 (H-2d/b) mice. Mice immunized with D protein and challenged by small-particle aerosol with a lethal dose of influenza virus were significantly protected against mortality from influenza A/H1N1 and A/H2N2 (p < 0.05-< 0.0000001), but not from A/H3N2 and influenza B viruses when compared with control mice. D protein did not induce serum virus-neutralizing antibody but caused virus to be cleared faster in immunized mice. Protection was long-lasting. In vivo depletion of either Lyt2 (CD8+) or L3T4 (CD4+) T cells with monoclonal antibodies led to abrogation of in vitro-generated CTL activity in CF6F1 mice and significant reduction in the protective efficacy of D protein against virus challenge in both Swiss and CF6F1 mice. These results suggest that protection was mediated by CD8+ and/or CD4+ cells and not antibody. Thus D protein, via a conserved sequence on the HA2 polypeptide, has the potential to induce partially cross-reactive CTL that may protect against influenza virus disease in humans.
Department of Microbiology and Immunology, Baylor College of Medicine, Houston, TX 77030-3498.
I N
IN
Mbawuike
S B
SB
Dillion
S G
SG
Demuth
C S
CS
Jones
T R
TR
Cate
R B
RB
Couch
D000336:Aerosols; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D005434:Flow Cytometry; D009980:Influenza A virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009500:Neutralization Tests; D009976:Orthomyxoviridae Infections / Q000517:prevention & control; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic / Q000276:immunology*; D014764:Viral Proteins / Q000276:immunology*; D014779:Virus Replication / Q000276:immunology
D000336:Aerosols; C079937:D protein, influenza A (A-PR-8-34-derived recombinant protein); D007252:Influenza Vaccines; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic; D014764:Viral Proteins