Dr. Hala Gamal Ali Ali El Daous :: Publications:

Most bovine leukemia virus (BLV)–infected cattle do not have clinical signs (aleukemic AL), but some develop persistent lymphocytosis (PL) and B-cell lymphosarcoma (enzootic bovine leucosis [EBL]). BLV infection is a well-known cause of chronic wasting disease, which is associated with a reduction in milk productivity and immunity in dairy cattle. However, the effect of BLV infection on beef cattle is not clear. The objective of this study was to investigate the effect of BLV infection on the productivity of slaughtered beef cattle. A total of 997 blood samples were collected from cattle in 2 slaughterhouses in Miyazaki prefecture, Japan. BLV-antibodies were tested in these cattle＇s blood samples using enzyme-linked immunosorbent assay (ELISA), to identify BLV-infected cattle. We compared blood parameters and carcass weight between BLV ELISA-positive and ELISA-negative cattle in two age groups : young (≤ 60 months) and elder (> 60 months) groups. The results showed that the proportion of ELISA-positive cattle in the young and elder groups were 22.8% and 24.9%, respectively. The number of white blood cells (WBCs) and lymphocytes in ELISA-positive cattle was significantly higher than that in ELISA-negative cattle in the young group. In addition to the number of lymphocytes, the number of monocytes and neutrophils were also significantly higher in BLV ELISA-positive cattle than in ELISA-negative cattle in the elder group. There was no significant difference in the carcass weight between ELISA-positive and ELISA-negative cattle in both groups. The results of this study suggest that BLV infection has an effect on the host immune response in beef cattle.