The objective of the present study was to analyze the apoptotic process in peripheral blood mononuclear cells (PBMC) and polymorphonuclear neutrophil leukocytes (PMN) in cows clinically affected with lymphosarcoma. Thirteen cows were studied. Of them, eight, that were referred because of inappetance, loss of body condition, diarrhoea, constipation, protrusion of third eyelid, and exophthalmia, ...

This article reports the selection of bovine leukemia virus (BLV) variants after continuous passage in cell lines or experimental animals. Two wild BLV strains isolated from 2 naturally infected Holstein dairy cows in Brazil (cow codes: 485 and 141) were used for the experimental infection of 1 sheep and FLK cells, and 1 rabbit and CC81 cells. Viral DNA was isolated several months after infecti...

Bovine leukemia virus latency is a viral strategy used to escape from the host immune system and contribute to tumor development. However, a highly expressed BLV micro-RNA cluster has been reported, suggesting that the BLV silencing is not complete. Here, we demonstrate the in vivo recruitment of RNA polymerase III to the BLV miRNA cluster both in BLV-latently infected cell lines and in ovine B...

Horizontal transmission is recognized as a major infection route for bovine leukemia virus (BLV), and cattle with high viral loads are considered to be a major infectious source in a herd. However, a correlation between viral loads and the risk of infection has been insufficient to use as a foundation for BLV control strategies. In this report, we examined the epidemiology of BLV infection and ...

The objective of this study was to compare an indirect ELISA, based on a purified 60 kDa envelope glycoprotein (gp51SU), with a Pourquire indirect ELISA for the detection of antibodies to the bovine leukemia virus. For conducting this research, 340 serum samples were collected from two different breeds of cows (Sarabi and Holestin) in different herds. Commercial ELISA revealed positive results ...

Bovine leukemia virus (BLV) is a retrovirus that causes enzootic bovine leucosis. To investigate the presence and genetic variability of BLV in the Caribbean for the first time, we preformed fluorescence resonance energy transfer (FRET)-PCR for the pol of BLV on DNA from whole blood of cattle from Dominica, Montserrat, Nevis and St. Kitts. Standard PCRs with primers for the env were used for ph...

by the immunodiffusion test was found to be the same as that detected by the IFA technique (5). Previous studies also showed that disruption of the virus is necessary for release of the antigen, suggesting that the antigen is an internal virion component (3, 6). The resistance of the BLV antigen to ether and acetone, and its presence in the cytoplasm of infected cells, are features which also c...

Enzootic bovine leukosis (EBL) is a retroviral infection that causes persistent lymphocytosis and lymphosarcoma in cattle. The economic importance of infection by bovine leukemia virus (BLV) is due to several factors, including losses in exportation, treatment of secondary infection, and reduction in dairy production. To facilitate the development of a national test that is sensitive, simple, a...

The RNA packaging process for retroviruses involves a recognition event of the genome-length viral RNA by the viral Gag polyprotein precursor (PrGag), an important step in particle morphogenesis. The mechanism underlying this genome recognition event for most retroviruses is thought to involve an interaction between the nucleocapsid (NC) domain of PrGag and stable RNA secondary structures that ...

Prostaglandin E(2) (PGE(2)), produced by macrophages, has important immune regulatory functions, suppressing a type 1 immune response and stimulating a type 2 immune response. Type 1 cytokines (interleukin-2 [IL-2], IL-12, and gamma interferon) increase in freshly isolated peripheral blood mononuclear cells (PBMCs) of animals with an early disease stage of bovine leukemia virus (BLV) infection,...