2004 Volume 57 Issue 12 Pages 779-784
A serological survey of the Aino virus (AINOV) conducted from August to October 2002 in Okayama Pre-fecture showed seroconversion to the virus in 79.6% of the sentinel calves and 90% of the farms examined. AINOV infection from early August 2002 to late March 2003 caused 29 cases of 77 abnormalities. Six fetuses were aborted, 10 calves were stillborn, 4 calves were premature, and 9 calves had congenital defects. Viruses were isolated from blood obtained from 5 sentinel calves in late August 2002 and from the cerebrum of an aborted fetus in early October 2002. Reverse transcription polymerase chain reaction and immunohistochemical analysis resulted in the diagnosis of an animal aged 24 months as AINOV infected. Abortions were more numerous and congenital abnormalities occurred at an earlier state of AINOV infection in this epidemic than in earlier ones. This is the first report to describe AINOV as a cause of encephalitis in naturally infected cattle.