DETECTION OF FELINE IMMUNODEFICIENCY VIRUS P24 ANTIGEN AND P24-SPECIFIC ANTIBODIES BY MONOCLONAL ANTIBODY-BASED ASSAYS

A panel of monoclonal antibodies (mAbs) detecting distinct B-cell epit opes on p24 core viral protein of feline immunodeficiency virus (FIV) were employed to develop immunoassays to measure p24 concentration in culture and serum samples, to localize p24 in FIV-infected cells and t issues, and to detect anti-p24 antibodies in cat sera. In its optimize d configuration the p24 capture assay detected as little as 0.25 ng/ml of protein. The assay was found at least as sensitive as the reverse transcriptase activity assay in FIV-infected lymphocyte cultures and p roved capable of detecting p24 antigen in acid pretreated sera from a high proportion of FIV-infected cats. The mAbs were also successfully used to detect the p24 antigen in permeated FIV-infected cells by flow cytometry and in tissue sections from FIV-infected cats by immunohist ochemical staining. Anti-p24 antibodies in FIV-infected cat sera were assayed by a competitive capture ELISA which readily identified occasi onal false positive results provided by a standard ELISA using purifie d whole FIV-coated wells.