AUTHOR=Nakatsuchi Ayumi , Bao Aronggaowa , Watanuki Sonoko , Matsuura Ryosuke , Borjigin Liushiqi , Bai Lanlan , Kuroda Maho , Matsumoto Yasunobu , Kohara Junko , Aida Yoko 

TITLE=Anti-BLV antibodies in whey correlate with bovine leukemia virus disease progression and BoLA-DRB3 polymorphism

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.1038101

DOI=10.3389/fvets.2022.1038101

ISSN=2297-1769

ABSTRACT=<sec><title>Introduction</title><p>Bovine leukemia virus (BLV) belongs to the family <italic>Retroviridae</italic> and is a causative agent for enzootic bovine leucosis, the most common neoplastic disease affecting cattle worldwide. BLV proviral load (PVL) is associated with disease progression and transmission risk but requires blood collection and quantitative PCR testing. Anti-BLV antibodies in whey have been used as a diagnostic tool for BLV infection; however, quantitative utilization has not been fully investigated. Furthermore, bovine leukocyte antigen (<italic>BoLA</italic>)-<italic>DRB3</italic> is a polymorphic gene associated with BLV infectivity and PVL, but its effect on anti-BLV antibody levels in whey from BLV infected dams is unknown. Therefore, we aimed to investigate whether it is possible to correctly predict PVL in the blood and milk based on the amount of anti-BLV antibodies in milk, and whether the <italic>BoLA-DRB3</italic> alleles associate with the amount of anti-BLV antibodies in milk.</p></sec><sec><title>Methods</title><p>We examined whey from 442 dams from 11 different dairy farms located in 6 prefectures in Japan, including susceptible dams carrying at least one <italic>BoLA</italic>−<italic>DRB</italic>3<sup>*</sup><italic>012:01</italic> or <sup>*</sup><italic>015:01</italic> allele related with high PVL, resistant dams carrying at least one <italic>BoLA-DRB3</italic><sup>*</sup><italic>002:01</italic>, <sup>*</sup><italic>009:02</italic>, or <sup>*</sup><italic>014:01:01</italic> allele related with low PVL, and neutral dams carrying other alleles.</p></sec><sec><title>Results</title><p>First, our results provided compelling evidence that anti-BLV antibody levels in whey were positively correlated with the anti-BLV antibody levels in serum and with BLV PVL in blood and milk, indicating the possibility of estimating BLV PVL in blood and milk by measuring anti-BLV antibody levels in whey. Thus, our results showed that antibody titers in milk might be effective for estimating BLV transmission risk and disease progression in the field. Second, we demonstrated that anti-BLV antibody levels in whey from BLV resistant dams were significantly lower than those from susceptible and neutral dams.</p></sec><sec><title>Discussion</title><p>This is the first report suggesting that the <italic>BoLA-DRB3</italic> polymorphism affects anti-BLV antibody levels in whey from BLV-infected dams. Taken together, our results suggested that anti-BLV antibody levels in whey, measured by enzyme-linked immunosorbent assay, may be a useful marker to diagnose the risk of BLV infection and estimate PVL in blood and milk.</p></sec>