Bovine leukemia virus: general characteristics, viral prevalence in South America and its impact on animal and human health

Abstract

Bovine leukemia virus (VLB) is a member of the Retroviridae family and the causative agent of enzootic bovine leukosis (EBL). This disease leads to economic losses in cattle herds and is transmitted horizontally through contact with infected fluids, such as blood, or vertically via in utero transmission and/or colostrum consumption by newborn calves. For EBL detection, the World Organisation for Animal Health recommends serological tests such as enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID), as well as polymerase chain reaction (PCR) tests, which detects proviral DNA segments in infected animals. VLB is prevalent in numerous countries, with herd prevalence reaching up to 90% in endemic areas such as Eastern Europe, several Asian countries, and South America. To date, eleven circulating genotypes have been reported worldwide. Recent findings have raised concerns regarding the oncogenic potential of VLB in humans due to the detection of proviral DNA in blood and breast tissue samples with adenocarcinoma. However, the association between VLB infection and tumor development remains inconclusive. Preventive measures, including selective culling, eradication programs, and improved management practices, depend on the regional prevalence of the disease. Although no commercial vaccines are currently available, vaccine development efforts are underway in Argentina. EBL remains one of the most critical bovine diseases in the country, and continuous, systematic research in collaboration with government agencies is essential for implementing sanitary measures aimed at reducing the prevalence of this viral infection.