Here, we used a sheep bioassay to determine the effect of freezing colostrum to prevent the transmission of bovine leukaemia virus (BLV) among neonatal calves. Leukocytes were isolated from the colostrum of a BLV-infected Holstein cow and were then either left untreated (control) or freeze-thawed. A sheep inoculated intraperitoneally with the untreated leukocytes was infected with BLV at 3 weeks after inoculation, whereas the sheep inoculated with treated leukocytes did not become infected. The uninfected sheep was then inoculated with leukocytes isolated from the colostrum of another BLV-infected Holstein cow after freezing the colostrum; the sheep was not infected with BLV after this inoculation also. Finally, this sheep was inoculated with leukocytes isolated from the colostrum of another virus-infected cow without freezing treatment, and it became infected with BLV at 4 weeks after inoculation. The results indicate that colostrum should be frozen as a useful means of inactivating the infectivity of BLV-infected lymphocytes.
(Exotic Disease Research Division)
References:
Kanno T. et al (2014) J. Vet. Med. Sci. 76(2): 255-257
