Figure 4. v-bcl-2 and v-cyclin are critical for persistent replica- tion of HV68 in IFN- / mice. IFN- / mice were in- fected with 106 PFU of virus and peritoneal cells were harvested at 16, 28, or 42 d after infection for quantitation of frequency of cells reactivating virus (A–C, left pan- els), amount of persistent virus (A–C, right panels), and fre- quency of latently infected cells (D). Data represent results of two to three experiments (mean SEM), with each experiment containing cells pooled from five mice. Since at day 42 time point, no significant difference be- tween v-cyclin.MR and wt HV68 was observed, only v-cy- clin.MR was checked for day 16 and day 28 time points along with two independent isolates of v-bcl-2.Stop1 and v-cyclin.Stop. For day 42 experiments, v-bcl-2 mutant infection included two experiments with v-bcl-2.Stop1 and one experiment with v-bcl- 2.Stop2. Similarly, v-cyclin mu- tant infection included two ex- periments with v-cyclin.Stop and one experiment with v-cy- clin.LacZ at day 42 time point. The decreased frequencies of ex vivo reactivation and persistent productive replication of both v-bcl-2 mutant and v-cyclin mu- tant compared with wt HV68 and v-cyclin.MR were statistically significant as follows: day 16 ex vivo reactivation, v-bcl-2.Stop1 versus v-cyclin.MR, P 0.007; v-cyclin.Stop versus v-cy- clin.MR, P 0.003; for day 16 persistent productive replication, v-bcl-2.Stop1 versus v-cy- clin.MR, P 0.014; v-cy- clin.Stop versus v-cyclin.MR, P 0.011, for day 28 ex vivo re- activation, v-bcl-2.Stop1 versus v-cyclin.MR, P 0.0009, v-cy- clin.Stop versus v-cyclin.MR, P 0.0001; for day 28 persistent productive replication, v-bcl- 2.Stop1 versus v-cyclin.MR, P 0.0326, v-cyclin.Stop versus v-cyclin.MR, P 0.028, and for day 42 ex vivo reactivation, v-bcl-2 mutant versus wt HV68, P 0.0008, v-bcl-2 mutant versus v-cyclin.MR, P 0.0003, v-cyclin mutant versus wt HV68, P 0.0001, v-cyclin mutant ver- sus v-cyclin.MR, P 0.0001; for day 42 persistent productive replication, v-bcl-2 mutant versus wt HV68, P 0.027, v-bcl-2 mutant versus v-cy- clin.MR, P 0.008, v-cyclin mutant versus wt HV68, P 0.032, v-cyclin mutant versus v-cyclin.MR, P 0.011. The difference in frequency of genome positive cells at day 16 and day 42 were not statistically significant between the v-cyclin.MR versus v-bcl-2.Stop1 and v-cyclin.MR versus v-cyclin.Stop. the v-cyclin.MR, v-bcl-2 mutant, and the v-cyclin mutant virus infected mice (data not shown). We noted that the phenotype of v-bcl-2 and v-cyclin deficient viruses during chronic infection of IFN- / was in contrast to the lack of a phenotype for these viruses in growth during acute infection of normal and IFN- / mice (Fig. 2 C). We considered the hypothesis that data on acute infection using IFN- / is not comparable to data on chronic infection from IFN R / mice. However, the phenotypes of IFN- / mice and IFN R / are similar using a number of different routes of infection and doses of wt HV68 (32, 38). To determine if decreased virulence of 936 v-bcl-2 and v-cyclin Are Chronic Disease Herpesvirus Genes