An RT-PCR assay for the enzyme activity of reverse transcriptase capable of detecting single virions

We developed a sensitive assay for the enzyme activity of reverse transcriptase (RT) by setting up an RT-PCR assay containing an ample amount of exogenous RNA template but no added RT except that provided in the sample to be tested. This assay can detect less than 100 molecules of RT, which is approximately 10 super(6) times more sensitive than a conventional RT assay. The assay detects the RT activity present in single virus particles. Because the assay is general for most, if not all, RTs and is several orders of magnitude more sensitive than ELISA or infectivity assays, it also has promise as a tool for discovery of new retroviruses.