Description:
<jats:title>Abstract</jats:title>
<jats:p>Influenza viruses are segmented negative-strand RNA viruses which do not integrate into the genome of their host and are incapable of latent infection. Although infectious virus is cleared from the lungs within ~7-10dpi we have shown that trace quantities of processed peptide antigen remain in the draining lymph nodes of the respiratory tract for ~2 months and correspond with local changes in the migration patterns of pathogen-specific CTL in the respiratory tract. Prolonged antigen presentation is a common characteristic of infection with multiple strains of influenza virus, but antigen clearance can occur with much faster kinetics after infection with some isolates. Comparisons between these different isolates show that the processed peptide antigens reinforce expression of two homing receptors (CD69 and CD103) in the lungs which help activated virus-specific CD8 T cells colonize the mucosal tissues during a mild inflammatory response. Furthermore, virus-specific CTL which lacked CD103 expression were less efficient in clearing infectious virus from the lungs, than wild type cells, after heterosubtypic challenge. These data indicate that prolonged antigen presentation is required to reinforce local CTL responses in the lungs and thus explains why protective cellular immunity is short-lived.</jats:p>