Relationship between establishment of persistent infection of haemagglutinating virus of Japan and the properties of the virus.

The infectious virus (HVJ-pi) obtained from BHK cells persistently infected with haemagglutinating virus of Japan was found to be temperature-sensitive as well as causing little or no cytopathic effect (c.p.e.) and leading to establishment of carrier cultures in several cell lines at both permissive (32 degrees C) and non-permissive (38 degrees C) temperature. In order to obtain information about the role of HVJ-pi in the establishment of persistent infection, comparative studies were made of some phenotypic properties of HVJ-pi and HVJ-38 which was obtained by passing wild-type HVJ in eggs at 38 degrees C and was proved to be highly cytopathic. HVJ-pi differed from HVJ-38 in (1) temperature sensitivity in its ability to produce virus progeny, (2) infectivity for embryonated eggs, (3) neuraminidase activity, (4) the thermal stability of HA and neuraminidase activity, and (5) the polypeptide composition of BHK-grown viruses. B cells infected with HVJ-pi release haemagglutinin more efficiently, and less HA was accumulated on the cell membrane. In considering these results, it was concluded that the difference of envelope proteins might be involved in the striking difference in c.p.e. between HJV-pi and HVJ-38.