Virucidal effect of certain chemical contraceptives on Type 2 herpesvirus

Abstract

The virucidal effect of several chemical contraceptives was investigated and the findings are rrported. The supension of Type 2 herpes simplex virus, containing 10(6) to 10(7) tissue culture infectious doses per 0.1 ml., was inactivated on exposure to five different chemical contraceptives. For quantitative estimates of virucidal effect, 10 per cent solutions of these chemical contraceptives were tested with an exposure time of 10 minutes at room temperature. The methods for determination of residual infectivity included both virus assays in cultures of Vero cells and human embryo fibroblasts, as well as the intracranial inoculation of mice. Virus infectivity decreased 1,000- to 10,000-fold after contact with chemical contraceptives, indicating a substantial virucidal effect.

PIP: The frequent asymptomatic carriage of the Type 2 herpes virus by members of both sexes contributes to spread of the disease. This virus infection has been associated with the later development of cervical cancer. The virucidal effect of selected contraceptives, marketed for intravaginal use, was studied on Type 2 herpes virus. Preparations tested were Conceptrol, Cooper Creme, Preciptin gel, Lorophyn jelly, and Milex Cresent Jelly. Type 2 herpes virus (196-P10 of October 8, 1970) was used. An additional passage was made in human embryonic fibroblast cell culture. After 48 hours of incubation, ampules containing the infectious suspension were stored at -65 degrees C. This stock (TCID50), of virus was assayed in human embryonic fibroblastis and Vero cells (African green monkey kidney cell line). For use, the stock high titer (10 6 to 10 7 tissue culture infectious dose per .1 ml) virus suspension was serially diluted 10-fold. Initial 10% working dilutions of contraceptives and subsequent 10% dilutions of these were prepared in saline. Inoculated tissue culture tubes were incubated at 23 degrees C for 10 minutes. End points of infectivity were determined by reading the cytopathogenic effect. The intracerebral 50% lethal dose (LD50) of virus for mice was determined by injecting .03 ml/weaning mouse in each of 12 mice for each serial virus dilution. Injected mice were observed for 21 days to determine infectivity and lethal virus dose. To assure optimal conditions for the measurement of infectivity, the dilutions of virus before and after treatment with contraceptives were prepared in diluent containing 5% inactivated calf serum. No cytopathic effect was observed in the inoculated cell culture tubes beyond that attributed to the toxicity of contraceptives up to a dilution of 10 +-2% and 10 +-3%. A 1000-10,000 decrease in infectivity occurring after contact with the chemical contraceptives indicated a marked virucidal effect.