Fig. 4.

Virus release to the medium mediated by wild-type and mutant pUL34. Replicate cultures of Vero, wild-type pUL34-expressing, or Y68A mutant pUL34-expressing cells were infected at an MOI of 5 with wild-type virus HSV-1(F), UL34-null virus vRR1072(TK+), or Y68ARev. Residual virus was removed or inactivated with a low-pH wash, and at 18 h after infection total culture virus (gray bars) or culture supernatant (white bars) was titrated on WT UL34-expressing cells. Virus yields are expressed as PFU/ml. Each data point represents the mean of results from three independent experiments. Error bars indicate the range of values. The values in parentheses above each pair of bars indicate the percentages of total virus released to the medium calculated as the mean amount of released virus divided by the mean amount of total virus times 100. Low pH wash completely removed residual extracellular virus, as the titer of culture supernatant at 2 h postinfection was undetectable.