Maternally derived antibodies to Japanese encephalitis virus in cattle

Serum samples were collected from 55 pairs of calves that had not passed the first summer and their dams reared in Kagoshima from 1983 through 1985. They were investigated for the HI antibody to Japanese encephalitis virus (JEV) in calves and for the correlation of antibody levels between calves and their dams. The maternally derived antibody was detected in 35 of 55 calves (63.6%), showing the mean antibody titer of 12.4. A significant negative correlation (p less than 0.01) was noted between the age of calve and titer of passively acquired antibodies. The regression equation suggested that the maternal antibody disappeared from the calf serum at about 3 months of age. On the other hand, 37 of 55 dams (67.3%) were positive for HI antibody to JEV, and the mean titer of the antibody was 12.7. There was a significant correlation (p less than 0.01) in serum antibody titers between dams and their calves.