Fixed herpes simplex type 1-infected cells as antigen for in vitro lymphocyte proliferation.

Fixed herpes simplex virus type 1 (HSV-1)-infected Vero cells were used as antigen in the in vitro lymphocyte reactivity (LR) test and compared with extracellular HSV, HSV-infected cell extract and purified virions. The highest LR was measured after an incubation period of lymphocytes with the fixed HSV-infected Vero cells of 5-7 days. The LR appeared to be dependent on the lymphocyte to fixed HSV-infected cell ratio and was found to be optimal at a ratio of 10-20. The fixed HSV-infected cells could be stored at 6 degrees C without detectable loss of LR. Addition of high-titered anti-HSV pooled serum to the lymphocyte cultures with the fixed HSV-infected cells as antigen inhibited the LR. The highest reactivity was found using HSV-negative pooled serum. Lymphocytes from seropositive donors were stimulated by the fixed HSV-infected cells and the purified virions. LR to extracellular HSV and an extract of HSV-infected cells were negative for 5 and 2 out of 13 seropositive donors, respectively. Lymphocytes from seronegative donors were not stimulated by any of the HSV-antigen preparations. Fixed HSV-infected cells, which have the advantage that they are easy to prepare and can be stored at 6 degrees C for several months, are a good alternative to purified HSV-1 virions in the LR test.

Enhanced reactivation and enhanced mutagenesis of herpes simplex virus in normal human and xeroderma pigmentosum cells.

Enhanced reactivation (ER) and enhanced mutagenesis (EM) of herpes simplex virus type 1 were studied simultaneously in UV-irradiated stationary cultures of diploid normal human and xeroderma pigmentosum (XP) fibroblasts. Mutagenesis was assayed with unirradiated herpes simplex virus type 1 as a probe in a forward mutation assay (resistance to iododeoxycytidine). Dose-response studies showed that ER increased with the UV dose given to the virus. Optimal reactivation levels were obtained when normal cells and XP variant cells were exposed to a UV dose of 8 J . m-2 and the virus was irradiated with 150 J . m-2. Repair-deficient XP cells of complementation groups A, C, and D showed optimal reactivation levels with a UV dose to the cells of 1.0 J . m-2 and a UV dose to the virus of 40 J . m-2. The time course of appearance of ER and EM was also studied, both in the normal and XP cells. In all cell types except the XP variant cells, EM followed similar kinetics of appearance as did ER. Maximal activities occurred when infection was delayed 1 or 2 days after cell treatment. In XP variant cells, however, maximal expression of the EM function was significantly delayed with respect to ER. The results indicate that ER and EM are transiently expressed in normal and repair-deficient XP cells. Although both phenomena may be triggered by the same cellular event, ER and EM appear to be separate processes that occur independently of each other.