FIG. 2.
Kinetics of LPS-induced MCMV reactivation. Mice latently infected with MCMV received a sublethal dose of LPS (15 μg/kg/0.2 ml i.p.), and cohorts of five were analyzed at 1-, 2-, and 3-week intervals for MCMV GB and β-actin transcription. RT-PCR of lung homogenates from mice latently infected with MCMV shows LPS-induced reactivation of viral transcription is similar to that seen following bacterial peritonitis, becoming detectable by 1 week and persisting for at least 3 weeks after LPS injection. Detection of reactivation required nested RT-PCR at weeks 1 and 2; reactivation became detectable by less sensitive first-round RT-PCR by week 3. Molecular reactivation was confirmed by IVPA with recovery of live virus from five of five week 3 mice receiving LPS (mean ± SEM, 198 ± 27 PFU). Mice receiving saline alone (0.2 ml i.p.) were evaluated at week 3 only and showed no evidence of reactivation by RT-PCR (see above) or by IVPA or focused expansion assay (data not shown). Each lane represents results from one mouse. Positive (Pos) and negative (Neg) controls refer to technique controls. No-RT reactions were also performed in parallel for MCMV GB and β-actin and were all negative (not shown).