A rapid antiviral in situ enzyme-linked immunosorbent assay for feline immunodeficiency virus

An in situ enzyme-linked immunosorbent assay (ELISA) was developed as a rapid alternative to the focal infectivity assay (FIA) for screening potential anti-retroviral molecules. The assay utilizes 96-well microtiter plates to allow for determination of antiviral effect and cytotoxicity of multiple compounds simultaneously. In contrast to the FIA which requires visual scoring of foci under low-power microscopy, the 96-well ELISA is read spectrophotometrically based on the soluble alkaline phosphatase substrate, p-nitrophenyl phosphate. The IC50 and CC50 values for several antiretroviral compounds were determined using the ELISA and results were confirmed by FIA. In all cases, compounds assayed by the newly described ELISA exhibited IC50 values in agreement with literature values derived from either the FIA or reverse transcriptase assays.