A highly reliable, sensitive, flow cytometric/fluorometric assay for the evaluation of the anti-HIV activity of antiviral compounds in MT-4 cells.

Infection of human T4 lymphocyte MT-4 cells with human immunodeficiency virus (HIV) results in cell death 4-5 days after infection. We have now developed a highly sensitive and rapid procedure for estimating the cytopathic effect of HIV in MT-4 cells. This method is based on fluorometric as well as flow cytometric evaluation of HIV-infected MT-4 cultures. By the use of fluorescein diacetate (FDA), a non-fluorescent diacetyl fluorescein ester that becomes fluorescent upon hydrolysis by esterases present in the cytoplasm of viable cells, as few as 100-200 viable MT-4 cells can be accurately determined. Applying this new method to HIV-infected MT-4 cell cultures treated with differing concentrations of the potent anti-HIV agent azidothymidine (AZT), we obtained a virus-inhibitory dose-response comparable to those obtained by the conventional (labour-intensive and time-consuming) methods. The FDA-based cell viability assay appears particularly suited for the rapid, reliable and sensitive evaluation of potential anti-AIDS agents in cell culture.