Abstract
An outbreak of an acute respiratory infection with fever of short duration and nasal secretion occurred among colts at a farm in Aomori Prefecture, Japan.
Nasal secretions obtained from 19 sick colts were inoculated into horse kidney cell cultures and 12 viral strains of the same properties including antigenicity were isolated. Increase in titers of complement fixation and neutralization against the isolated virus as well as the Kentucky D strain of equine abortion virus was clearly demonstrated after the illness in all of the colts from which the materials for virus isolation were obtained.
These isolated agents were considered to be equine abortion virus on the bases of formation of intranuclear inclusions in horse kidney cells in culture, physico-chemical properties, behavior in various cell cultures and complement fixation reaction. However, the isolates, as, the H-45 strain isolated from aborted fetus in Hokkaido, Japan, were found to differ from the Kentucky strain isolated in U.S.A; The isolated and the H-45 strain could be readily differentiated by neutralization test from the American strain, although some cross-reaction was noted, and failed to infect hamsters.
These findings provide etiological evidence for the presence of respiratory infection with equine abortion virus among Japanese colts.
