ISOLATION AND CHARACTERIZATION OF NEW WILD-TYPE ISOLATES OF BOVINE LENTIVIRUS

Two new isolates of bovine lentivirus, also known as bovine immunodefi ciency-like virus (BIV), were obtained from a seropositive cattle herd in Florida. This is the first report of new isolates of BIV since the original BIV strain, R29, was isolated in 1969. The two new BIV isola tes were derived from blood buffy coat cells cocultivated in vitro wit h fetal bovine lung cell cultures. The new isolates differed in vitro from the original R29 isolate in replication and syncytium formation i n fetal bovine lung cells. Both new isolates were confirmed as BIV by immunofluorescence assay, Western blotting (immunoblotting), and polym erase chain reaction. Sequence analyses of the polymerase chain reacti on pol gene product showed 92.6 and 93.6% homology to the published nu cleotide sequence of BIV R29-127, a molecular clone derived from BIV R 29. Each of the new BIV isolates was inoculated into two calves, and v irus was recovered between 5 and 10 days postinoculation (p.i.), with BIV seroconversion between 10 and 21 days p.i. Virus was recoverable a nd antibody was detectable for at least 4 months p.i. Two calves devel oped a transiently elevated mononuclear cell count, similar to what wa s reported for BIV R29 in the original experimental calf inoculations. No other clinical abnormalities were observed.