Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 24, 1996
Publication Date: N/A
Interpretive Summary: Bovine lentivirus, known as bovine immunodeficiency-like virus (BIV), causes a persistent viral infection of cattle that appears to be widespread in the cattle population around the world. Although this virus is called BIV, effects on cells of the cellular immune system are unknown, as well as specific cell types that are infected by the virus. In the current study, cattle were inoculated with BIV FL112, an isolate known to cause an increase in white blood cell numbers in cattle, indicating a biological effect on the immune system of the infected animal. A very precise technique called flow cytometry was used to analyse changes in cell populations in the blood of infected cattle as compared with mock infected cattle. Data showed that the increase in white blood cell numbers in infected cattle was due to an increase in one cell type, called B cells, and that BIV infects several different cell types of the immune system. These results are very different from the human immunodeficiency virus (HIV) where changes in immune cell populations show a decrease in CD4 cells and only one cell type, CD4, is infected by the virus. While BIV is genetically similar to several immune deficiency causing viruses, these data do not show that BIV is a classical immune deficiency causing virus.
Technical Abstract: Bovine immunodeficiency-like virus (BIV) was first isolated in 1972 (VanDerMaaten, et al, JNCI; 49:1649). Much work has been done on the molecular characterization of BIV using the original BIV R29 isolate; however, R29 is believed to be attenuated since it no longer causes either mononuclear cell number increases or detectable enlargement of lymphatic nodules in experimentally infected cattle. The host cell tropism and changes in host peripheral blood lymphocyte populations following infection with BIV are unknown. Recently, we isolated and characterized a field isolate of BIV, FL112 (Suarez, et al, 1993, J Virol. 67:5051), that causes a transient, mononuclear cell lymphocytosis in experimentally infected cattle. In the present study, cattle were inoculated with BIV PL112 and data from flow cytometry showed that BIV causes a B cell lymphocytosis with no consistent, significant changes in other mononuclear cell populations including CD3+, CD4+, and CD8+. Cell sorting and PCR amplification were used to show that BIV is pantropic. Proviral DNA was present in CD3+, CD4+, CD8+, B-cell, monocyte, and WC-1 (gamma/delta T cells, null cells) by 3-5 days postinoculation and also at 2.5 years postinoculation.