Replication kinetics of PrV-ΔUL31 and PrV-ΔUL34 mutants. RK13 (A) or RK13-DrdI (B) cells carrying a genomic fragment encompassing PrV genes UL31 to UL35 were infected with PrV-Ka, PrV-ΔUL31, PrV-ΔUL31Pass, PrV-ΔUL34, or PrV-ΔUL34Pass at an MOI of 5. At the indicated times postinfection, infected cells were scraped into the supernatant and virus progeny titers were determined. Mean values of three independent assays and corresponding standard deviations are given.