Kinetics of FV infection and kinetics of effector CD8⁺ T-cell responses during acute FV infection. (A) Viral loads in lymph nodes, spleen, and bone marrow (infectious centers) were determined at different time points after FV infection. Each dot represents the mean number + SEM of virus-infected cells per 1 million nucleated cells for a group of 5 to 10 mice. Data were pooled from 2 independent experiments with similar results. (B) Kinetics of effector CD8⁺ T cells specific for the FV gagL epitope during acute FV infection. CD8⁺ T cells from lymph nodes, spleen, and bone marrow of FV-infected mice were stained for D^bgagL class I tetramers to identify FV-specific effector T cells. Costaining experiments indicated that all tetramer-positive CD8⁺ T cells also expressed the CD43 activation marker (data not shown). Each dot represents the mean number + SEM of CD8⁺ tetramer⁺ T cells per 1 million nucleated cells for a group of 5 to 10 mice. Data were pooled from 3 independent experiments with similar results. (C-D) Flow cytometry was used to detect intracellular granzyme B or the degranulation marker CD107a in effector CD8⁺ T cells (CD43⁺). The kinetic analysis was performed at different time points after FV infection. Shown are the numbers of CD8⁺ T cells expressing granzyme B (GzmB; C) or CD107a (D) from lymph nodes, spleen, and bone marrow. Each dot represents the mean number + SEM per 1 million nucleated cells for a group of 5 to 10 mice. Data were pooled from 2 independent experiments with similar results. (E) Splenocytes from naive mice were loaded with D^bGagL peptide and labeled with CFSE. Target cells were injected intravenously into naive and acutely infected (10 dpi) mice. Two hours after transfer, donor cells from lymph nodes, spleen, and bone marrow were analyzed. The figure shows the percentage of target cell killing in the investigated organs. Three independent experiments with similar results were performed. Differences between investigated organs were analyzed by the unpaired Student t test. Statistically significant differences between the organs are indicated in the figure. (F-G) Splenocytes from naive mice were loaded with D^bGagL peptide and labeled with CFSE. Target cells were injected intravenously into naive mice and in mice at different time points after FV infection. The figure shows the percentage of target cell killing at different time points after FV infection in the spleen (F) and in bone marrow (G). Two independent experiments with similar results were performed.