An Infectivity Assay for Bovine Leukemia Virus Using the Immunoperoxidase Technique1

This report describes the development of a 7-day infectivity assay for bovine leukemia virus (BLV) which is based on the induction of the major internal virion antigen (a protein with a molecular weight of 25,000) in susceptible indicator monolayer cell cultures. In this assay, the antigen is detected in the indicator cells by the immunoperoxidase antibody technique using a specific rabbit antiserum to a BLV protein with a molecular weight of 25,000. The immunoperoxidase infectivity assay is specific, quantitative, reproducible, and more sensitive than the previously described syncytia induction assay. The immunoperoxidase ¡nfectivity assay can be applied to the de tection of BLV-infected cells and provides a reliable method for the direct diagnosis of BLV infection in cattle.