Controversies and clarifications regarding bovine lentivirus infections. Subcommittee for the Bovine Retrovirus Committee, US Animal Health Association

Sensitive and specific detection of bovine immunodeficiency virus and bovine syncytial virus by 5' Taq nuclease assays with fluorescent 3' minor groove binder-DNA probes

Sensitive assays are required to detect bovine retroviruses in donor cattle used for the in vivo preparation of Australian tick fever vaccines. 5' Taq nuclease assays using 3' minor groove binder DNA probes (TaqMan)MGB) were developed and compared to conventional PCR assays for the sensitive detection of bovine syncytial virus (BSV) and bovine immunodeficiency virus (BIV). Seven beef and dairy herds were screened to evaluate these tests. Comparative sensitivities of PCR tests were determined by testing log(10) dilutions of plasmids with inserts containing corresponding provirus sequences. Published PCR assays targeting BIV env sequences did not adequately amplify Australian BIV sequences. Pol sequences from Australian strains of BIV and BSV were used to design TaqMan MGB assays, which improved sensitivity 10-fold (BIV) and 100-fold (BSV), respectively, over conventional PCR tests. This is the first report of Australian sequences of BIV and BSV and the first 5' Taq nuclease assays described to detect these viruses. These methods could be applied to future studies requiring sensitive detection of these two bovine retroviruses.

Natural bovine lentiviral type 1 infection in Holstein dairy cattle. I. Clinical, serological, and pathological observations

Clinical, serological, and pathological abnormalities observed in Holstein cows naturally infected with bovine lentivirus 1 bovine immunodeficiency virus (BIV) and other infections were progressive and most commonly associated with weight loss, lymphoid system deficiency, and behavioral changes. Clinical evidence of meningoencephalitis was dullness, stupor, and occasional head or nose pressing postures. The polymerase chain reactions associated the BIV provirus with the lesions in the central nervous system and lymphoid tissues. Multiple concurrent infections developed in retrovirally infected cows undergoing normal stresses associated with parturition and lactation. A major functional correlate of the lymphoreticular alterations was the development of multiple secondary infections which failed to resolve after appropriate antibacterial therapy. The chronic disease syndrome in dairy cows associated with BIV may be useful as a model system for investigation of the pathogenesis of the nervous system lesions and lymphoid organ changes that occur in humans with lentiviral infection.

Natural bovine lentivirus type 1 infection in Holstein dairy cattle. II. Lymphoid tissue lesions

Bovine immunodeficiency virus (BIV) in Holstein cows was associated with morphologic evidence of lymphoid organ deficiency. Cows were subjected to normal management practices including parturition and lactation without adverse environmental stresses. During the clinical disease process there was marked weight loss and wasting with frequent and severe concurrent infections. Lymphoid follicular hyperplasia and dysplasia in lymph nodes, and hypertrophy and hyperplasia in hemal lymph nodes were characteristics of the lymphoid tissues. Atrophy of lymphoid cell compartments with depletion of lymphocytes and a lymphocytic lymphoid folliculitis were components of the lymphoid system pathology. The nodal tissue lesions resembled those observed in feline, simian, and human lentiviral disease. A functional correlation with immune system deficiency was the development of multiple bacterial infections which failed to resolve after appropriate therapy. The BIV-associated disease syndrome in dairy cows may be useful as a model system for investigation of the pathogenesis of the lymphoid organ changes that occur in humans and animals with lentiviral infection.