Cellular immune responses to recurring influenza strains have limited boosting ability and limited cross-reactivity to other strains.
Influenza vaccine provides protection against infection with matched strains, and this protection correlates with serum antibody titres. In addition to antibodies, influenza-specific CD8+ T-lymphocyte responses are important in decreasing disease severity and facilitating viral clearance. Because this response is directed at internal, relatively conserved antigens, it affords some cross-protection within a given subtype of influenza virus. With the possibility of a broader A(H1N1) Mexico outbreak in the fall of 2009, it appeared worthwhile studying the degree of cellular immune response-mediated cross-reactivity among influenza virus isolates. The composition of the 2006-2007 influenza vaccine included the A/New Caledonia/20/1999 strain (comprising a virus that has been circulating, and was included in vaccine preparations, for 6-7 years) and two strains not previously included (Wisconsin and Malaysia). This combination afforded us the opportunity to determine the degree of cross-reactive cellular immunity after exposure to new viral strains. We analysed the antibody responses and the phenotype and function of the T cell response to vaccine components. The results obtained show that antibody responses to A/New-Caledonia were already high and vaccination did not increase antibody or cytotoxic T lymphocyte responses. These data suggest that repeated exposure to the same influenza stain results in limited boosting of humoral and cellular immune responses.
Keynan
Y
Y
Department of Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
Card
C M
CM
Ball
B T
BT
Li
Y
Y
Plummer
F A
FA
Fowke
K R
KR
D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D056738:Cross Protection; D003429:Cross Reactions; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D009980:Influenza A virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology*; D008350:Manitoba; D008875:Middle Aged; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000914:Antibodies, Viral; D007252:Influenza Vaccines