Abstract
BackgroundBovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis (EBL). The incidence of EBL in Japan is increasing annually; and the cases of EBL in cattle younger than 2 years old has been reported. Therefore, it is vital to find a method to control BLV infection, especially in young calves. In this study, to evaluate the protective ability of colostral antibodies against BLV infection, as well as the potential for BLV infection mediated by colostrum/milk, we investigated temporal fluctuations in the anti-BLV antibody titer and BLV proviral load (PVL) in colostrum/milk and peripheral blood of six infected dams during lactation. The association between PVL and antibody titer in colostrum and peripheral blood was then investigated using samples from a further twenty-seven cattle. Antibody concentrations were measured with a Syncytium-induction Inhibition Assay using colostral/milk whey and serum. PVL in peripheral blood and colostrum was measured by real-time PCR.ResultsColostral antibodies showed high inhibitory activity until day 3 of lactation. The antibody titer and PVL in peripheral blood showed lesser changes than those in colostrum/milk throughout lactation. The colostral antibody titer was significantly higher than the serum antibody titer in all samples, whereas the colostrum PVL was significantly lower than the blood PVL. The blood PVL showed a significant correlation with serum antibody titer, colostrum PVL, and colostral antibody titer. However, there were no major correlations between the serum and colostral antibody titers.ConclusionsThis is the first report investigating the temporal changes in colostral antibody titer in terms of inhibiting BLV infection in vitro. The results of antibody detection by Syncytium-induction Inhibition Assay suggested that the protective activity of the colostral antibodies against BLV infection would be conferred by anti-BLV gp51 antibody. The high antibody titer of colostral whey suggests that colostral whey could be a potential source of antibodies with a low risk of infection in neonatal calves.
Highlights
Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis (EBL)
To evaluate the protective ability of colostral antibodies against BLV infection, as well as the potential for BLV infection mediated by colostrum/ milk, we investigated the fluctuations in the antibody titer and proviral load (PVL) in the colostrum/milk and peripheral blood of infected dams during the lactation period
It can be concluded that the protective effect of colostral antibodies in BLV-infected cattle against BLV infection was conferred by anti-gp51 antibody, as has been observed in serum
Summary
Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis (EBL). To evaluate the protective ability of colostral antibodies against BLV infection, as well as the potential for BLV infection mediated by colostrum/milk, we investigated temporal fluctuations in the anti-BLV antibody titer and BLV proviral load (PVL) in colostrum/milk and peripheral blood of six infected dams during lactation. The loss of young successor or fattening cattle can cause major economic damage to farms Even if they are not affected by EBL, these animals would shed the virus within the farm for a longer time than cows infected at an older age. To evaluate the protective ability of colostral antibodies against BLV infection, as well as the potential for BLV infection mediated by colostrum/ milk, we investigated the fluctuations in the antibody titer and proviral load (PVL) in the colostrum/milk and peripheral blood of infected dams during the lactation period. The association between PVL and the antibody titer in the colostrum and peripheral blood were investigated
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