Isolation and characterization of new wild-type isolates of bovine lentivirus.

Two new isolates of bovine lentivirus, also known as bovine immunodeficiency-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 isolates were derived from blood buffy coat cells cocultivated in vitro with fetal bovine lung cell cultures. The new isolates differed in vitro from the original R29 isolate in replication and syncytium formation in fetal bovine lung cells. Both new isolates were confirmed as BIV by immunofluorescence assay, Western blotting (immunoblotting), and polymerase chain reaction. Sequence analyses of the polymerase chain reaction pol gene product showed 92.6 and 93.6% homology to the published nucleotide sequence of BIV R29-127, a molecular clone derived from BIV R29. Each of the new BIV isolates was inoculated into two calves, and virus was recovered between 5 and 10 days postinoculation (p.i.), with BIV seroconversion between 10 and 21 days p.i. Virus was recoverable and antibody was detectable for at least 4 months p.i. Two calves developed a transiently elevated mononuclear cell count, similar to what was reported for BIV R29 in the original experimental calf inoculations. No other clinical abnormalities were observed

Characterization of Early Pathogenic Effects after Experimental Infection of Calves with Bovine Immunodeficiency-Like Virus

The early pathogenic effects of bovine immunodeficiency-like virus (BIV) were studied in calves experimentally inoculated with BIV. All animals inoculated with BIV R29-infected cells seroconverted by 6 weeks postinoculation, and BIV was recoverable from each animal at 2 weeks postinoculation. However, levels of BIV replication in vivo appeared to be low. In situ hybridization studies indicated that during peak periods of viral replication in vivo, less than 0.03% of peripheral blood mononuclear cells were expressing detectable levels of viral RNA. Moreover, the levels of viral RNA in these cells in vivo were less than 1/10 the levels observed in persistently infected cells in vitro. BIV-inoculated calves had significantly higher numbers of circulating lymphocytes, and follicular hyperplasia was observed in lymph nodes, hemal nodes, and spleen. The histopathological changes observed in BIV-infected calves were similar to changes found early after infection with the immunosuppressive lentiviruses, including human immunodeficiency virus type 1.This article is from Journal of Virology 66 (1992): 1074.</p

Characterization of early pathogenic effects after experimental infection of calves with bovine immunodeficiency-like virus.

The early pathogenic effects of bovine immunodeficiency-like virus (BIV) were studied in calves experimentally inoculated with BIV. All animals inoculated with BIV R29-infected cells seroconverted by 6 weeks postinoculation, and BIV was recoverable from each animal at 2 weeks postinoculation. However, levels of BIV replication in vivo appeared to be low. In situ hybridization studies indicated that during peak periods of viral replication in vivo, less than 0.03% of peripheral blood mononuclear cells were expressing detectable levels of viral RNA. Moreover, the levels of viral RNA in these cells in vivo were less than 1/10 the levels observed in persistently infected cells in vitro. BIV-inoculated calves had significantly higher numbers of circulating lymphocytes, and follicular hyperplasia was observed in lymph nodes, hemal nodes, and spleen. The histopathological changes observed in BIV-infected calves were similar to changes found early after infection with the immunosuppressive lentiviruses, including human immunodeficiency virus type 1