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Significant Impact of Sequence Variations in the Nucleoprotein on CD8 T Cell-Mediated Cross-Protection against Influenza A Virus Infections
BACKGROUND: Memory CD8 T cells to influenza A viruses are widely detectable in healthy human subjects and broadly cross-reactive for serologically distinct influenza A virus subtypes. However, it is not clear to what extent such pre-existing cellular immunity can provide cross-subtype protection aga...
Autores principales: | , , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2010
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2868023/ https://www.ncbi.nlm.nih.gov/pubmed/20485501 http://dx.doi.org/10.1371/journal.pone.0010583 |
Sumario: | BACKGROUND: Memory CD8 T cells to influenza A viruses are widely detectable in healthy human subjects and broadly cross-reactive for serologically distinct influenza A virus subtypes. However, it is not clear to what extent such pre-existing cellular immunity can provide cross-subtype protection against novel emerging influenza A viruses. METHODOLOGY/PRINCIPAL FINDINGS: We show in the mouse model that naturally occurring sequence variations of the conserved nucleoprotein of the virus significantly impact cross-protection against lethal disease in vivo. When priming and challenge viruses shared identical sequences of the immunodominant, protective NP(366)/D(b) epitope, strong cross-subtype protection was observed. However, when they did not share complete sequence identity in this epitope, cross-protection was considerably reduced. Contributions of virus-specific antibodies appeared to be minimal under these circumstances. Detailed analysis revealed that the magnitude of the memory CD8 T cell response triggered by the NP(366)/D(b) variants was significantly lower than those triggered by the homologous NP(366)/D(b) ligand. It appears that strict specificity of a dominant public TCR to the original NP(366)/D(b) ligand may limit the expansion of cross-reactive memory CD8 T cells to the NP(366)/D(b) variants. CONCLUSIONS/SIGNIFICANCE: Pre-existing CD8 T cell immunity may provide substantial cross-protection against heterosubtypic influenza A viruses, provided that the priming and the subsequent challenge viruses share the identical sequences of the immunodominant, protective CTL epitopes. |
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