Bovine Leukemia Virus: Origin, Prevalence, Phylogenetic Diversity, Risk Factors, and Strategies for Control

Bovine leukemia virus (BLV) is classified as a Deltaretrovirus and shows close genomic and biological similarities with human T-cell leukemia viruses (HTLVs). It serves as the etiological agent for enzootic bovine leukosis (EBL), which stands as the most prevalent neoplastic disease affecting cattle globally. Additionally, BLV has been identified as a potential zoonotic pathogen, although the risk to human health remains a subject of ongoing research. The insidious nature of BLV lies in its predominantly subclinical presentation; the majority of BLV-infected cattle show no apparent symptoms. This subclinical nature poses challenges for disease detection and control, as infected animals can remain unnoticed carriers, contributing to the silent spread of the virus within herds. This characteristic also underscores the importance of surveillance and early detection strategies to monitor BLV prevalence and mitigate its spread. Despite concerted efforts in some regions to implement eradication programs, BLV continues to maintain a high prevalence worldwide. The persistence of BLV in cattle populations highlights the need for innovative and integrated approaches to control and manage the disease effectively. The development of a BLV vaccine represents a significant breakthrough in the fight against BLV transmission. A successful vaccine can not only reduce the incidence of BLV infection but also minimize the associated economic losses linked to reduced milk production, reproductive issues, and the premature culling of infected animals. Therefore, a comprehensive understanding of BLV, encompassing its origin, evolutionary patterns, epidemiology, risk factors, and control strategies, is pivotal. Such knowledge serves as the foundation for the development of effective vaccines, diagnostic tools, and control measures. Through this review, we aim to consolidate and present this multifaceted understanding of BLV, providing valuable insights and guidance for researchers, veterinarians, and policymakers involved in BLV prevention and control efforts globally.