Low pH inactivation of HSV-1 ANG path virions. Samples of HSV-1 ANG path or KOS were adjusted to a range of pHs as shown, incubated at 37°C for 10 min, and then neutralized to pH 7.6. Treated virions were incubated with Vero cells, and plaque formation was measured as an indication of virus entry and infection. The infectivity of samples that were treated with pH 7.2 was defined as 100%. Data are means of quadruplicate wells with standard deviation.