OPTIMIZATION OF THE REVERSE-TRANSCRIPTASE ASSAY FOR THE DETECTION OF VIRAL BURDEN IN MICE INFECTED WITH RAUSCHER MURINE LEUKEMIA-VIRUS

Rauscher murine leukemia virus induces an erythroleukemia in susceptib le strains of mice that is associated with splenomegaly and viremia. T his animal model has been used for evaluating the in vivo efficacy of potential anti-HIV agents. The in vivo antiviral activity of therapeut ic agents has usually been determined by measuring a reduction in the spleen weights of compound-treated mice or by quantitating viremia wit h the UV-XC plaque assay. The UV-XC assay, however, is time-consuming and labor-intensive. Virions of Rauscher murine leukemia virus, like o ther retroviruses, contain the enzyme reverse transcriptase. Quantitat ing the level of this enzyme in infected mouse sera provides a more ra pid measure of viremia in the animal. We have examined the effects of several reagents, including detergent, KCl, EGTA, dGMP, spermine, as w ell as protease and RNase inhibitors, on the reverse transcriptase ass ay. The optimized assay method was effective in evaluating the antivir al activity of AZT in the Rauscher murine leukemia virus in vivo model . The assay is also amenable to automation if large numbers of assays are required.