Evaluation of serum neutralizing antibodies to bovine coronavirus in cows & their calves using Hmlu-1 cells.

Between 1992 and 1993, 75 paired serum samples from Holstein dairy cows and their calves were collected from Aomori, Tochigi and Okinawa Prefectures, and the neutralizing antibody titres to bovine coronavirus (BCV) were determined using hamster lung (Hmlu)-1 cells. The anti-BCV antibody positive rate in the maternal serum samples was significantly lower (P < 0.001) in Okinawa (72%) than in Aomori (100%) or Tochigi (100%). The geometric mean tire (GMT) of anti-BCV neutralizing antibody was also significantly lower (P < 0.05) in maternal sera from Okinawa (89) than that of Aomori (229) or Tochigi (264). The anti-BCV neutralizing antibody titres in the sera of calves which had ingested the colostrum, significantly correlated with the antibody concentration of the maternal serum samples (P < 0.05). These results suggest an extensive BCV infection among the dairy cattle in these prefectures, with a varied pattern of distribution between the prefectures. Anti-BCV neutralizing antibody in the sera of newborn calves appeared to be transferred from their dams through colostrum.