1989 Volume 42 Issue 7 Pages 481-484
Sera collected from approximately 1, 300 pigs in 20 prefectures from 1976 to 1987 in Japan were examined for virus neutralization antibody (VNAb) against porcine reovirus types 1, 2 and 3. The positive rates of VNAb against type 1 in 1-and 2-month-old pigs were 60.2 and 15.4%, respectively. Afterwards, the rate was raised to 65.3% in 3-month-old and a level higher than 85% was maintained during 4-6 months of age. The positive rates of VNAb against types 2 and 3 were generally lower than that of type 1, however, these rates changed approximately parallel to that of type 1. These results suggested that the pigs were infected with these types of reovirus at about 2 months of age. On the other hand, chronologically, the positive rates of VNAb against types 1, 2 and 3 of the virus in pigs that had been raised from 1976 to 1987 ranged 64.3-99.0%(geometric mean (GM): 89.3%), 15.0-72.7%(GM: 44.0%) and 20.0-70.6%(GM: 50.3%), respectively. There was a few difference in positive rates between each observation period. Furthermore, it was revealed that the pigs raised in various districts of Japan had higher rates of VNAb against type 1 (75.8-98.0%) than those against types 2 and 3 (30.3-68.9%). From these findings it was considered that porcine reovirus has widely spread among pigs in Japan since 1976.
