CD8+ T-CELL MEMORY TO VIRUSES

Recent experiments show that laboratory mice infected once with an inf luenza A virus or with the murine parainfluenza type 1 virus, called t he Sendai virus, have enhanced numbers of cytotoxic T-lymphocyte precu rsors (>20x background) for life. Neither virus persists at the genome level, and the mice are maintained under conditions where there is no possibility of re-infection. These observations are highly relevant t o any understanding of CD8(+) cell memory and suggest that the clonal burst size associated with the primary challange is a key determining factor.