Evidence of natural bovine leukemia virus infection in llamas coexisting with cattle

During the last decades, camelid-derived products have gained increasing appreciation, positioning camelids within an emerging industry in several regions of the world. Their production in non-traditional areas creates new epidemiological scenarios due to interactions with other livestock species. These interactions may favor exposure to novel infectious agents, facilitate their spread, and potentially expand host ranges, with possible zoonotic implications. Consequently, it becomes essential to evaluate the role of camelids as susceptible hosts, reservoirs, or transmitters of infectious agents prevalent in other species. To date, the susceptibility of llamas to several bovine diseases, including bovine leukemia virus (BLV), remains unclear. The high prevalence of BLV infection in Argentine cattle, together with the frequent co-housing of cattle and llamas, raises the hypothesis of possible interspecies transmission. In this study, we evaluated the presence of the BLV genome in llamas from extra-Andean regions of Argentina. Blood samples from 31 animals with a recent history of cohabitation with cattle in Buenos Aires province (Argentina) were analyzed. Nucleic acids were extracted from peripheral blood mononuclear cells (PBMC), and BLV proviral DNA was detected by conventional PCR in 13 animals (41.9%). To assess whether infected PBMC were producing infectious particles, they were co-cultured with a bovine mammary epithelial cell line (MAC-T). The BLV genome was detected in MAC-T cells after ten passages. These results demonstrate that llamas can be naturally infected with BLV and may contribute to its interspecies transmission, with possible sanitary and productive implications.