INACTIVATION OF HTLV-III/LAV-INFECTED CULTURES OF NORMAL HUMAN LYMPHOCYTES BY NONOXYNOL-9 IN VITRO

This letter describes the in vitro inactivation of human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) by nonoxynol-9 a nonionic surfactant. Peripheral blood lymphocytes from HTLV-III-negative healthy volunteers not in any risk group for acquired immunodeficiency syndrome (AIDS) were separated by density-gradient centrifugation and incubated with HTLV-III in a culture medium of RPMI 1640. Reverse transcriptase activity assays were done on days 2 4 8 10 and 12 on cells treated with nonoxynol-9 immediately after inoculation. Nonoxynol-9 treated and untreated HTLV-III infected cell cultures were used as negative and positive controls. Treatment of HTLV-III with nonoxynol-9 at final concentrations of 0.05% or greater resulted in undetectable virus by the ID-50 assay. Toxicity controls suggested that 2.5% nonoxynol-9 and lower concentrations were appropriate for ID50 determinations. To assess the effect of the cytotoxicity of nonoxynol-9 on the reverse transcriptase assay pure nonoxynol-9 was diluted to 50% 25% 10% 5% and 1% and added to actively growing uninfected normal human lymphocytes. The reverse transcriptase activity of HTLV-III infected nonoxynol-9 treated cultures was significantly less than that of untreated infected cultures. Thus nonoxynol-9 at concentrations of 0.05% or more seems to inactivate HTLV-III in vitro while 1% or more reduces live counts of the target lymphocytes. Commercially available spermicides contain 1-5% nonoxynol-9 and the protective effect of such spermicides against sexual transmission of HTLV-III via sperm should be considered.