FIG 4.

MHV68 latency increases the number of virus-specific effector CD4⁺ T cells during acute LCMV infection. Ten-week-old naive C57BL/6 mice were i.n. infected with 10⁴ PFU of MHV68 or medium. Thirty-five days postinfection, mice were challenged with serum-free RPMI or 2 × 10⁵ PFU of LCMV Armstrong i.p. (A) On day 8 post-LCMV infection, splenocytes were harvested and stimulated with the indicated epitope, and the numbers of CD4⁺ T cells producing IFN-γ and TNF-α and IL-2 were determined. (B) The results from panel A were quantitated. The average for each is indicated by the horizontal bar. *, significant difference between mice infected with LCMV and mice infected with both LCMV and MHV68 (P ≤ 0.05). Five to 12 mice were harvested in two independent experiments.