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.