FIG. 2.

Replication of parent and chimeric FIV in feline cells following transfection and cell-free infection. Replication was investigated by RT assay of culture supernatants from transfected CrFK cells (a) or from CrFK cells (b) and primary feline PBMC (c) infected in a cell-free manner by each virus. RT activity for each clone is expressed as the mean ± standard error of the mean (counts per minute per milliliter) of triplicate samples from three independent wells. Significant differences in RT activity relative to control cultures were determined by ANOVA and the Tukey-Kramer posthoc test. (a) Increased RT activity was detected beyond 3 days only in CrFK cells transfected with Petaluma or FIV-ChTM. Significant differences between mock- and FIV-transfected cultures were observed at day 1 for all clones (P < 0.01) and at days 3, 5, and 7 for 34TF10A and FIV-ChTM (P < 0.001). (b) Elevated RT activity relative to controls was detected at all days p.i. (P < 0.001) in CrFK cells infected with Petaluma or FIV-ChTM. Activity in CrFK cells infected with FIV-ChSU or FIV-ChV35 was increased at day 1 p.i. only (P < 0.001). RT levels in Petaluma-infected cells exceeded thoaw in FIV-ChTM-infected cells at days 7, 10, and 14 (P < 0.005). (c) Compared to mock-infected controls, increased RT activity that peaked at day 10 p.i. was detected in all FIV-infected PBMC cultures. (P < 0.001 at all days). RT activity was significantly greater in PBMC infected with V1CSF, Petaluma, or FIV-Ch than in cells infected with the other viruses at days 7, 10, and 14 p.i. (P < 0.005).