Experimental infection in newborn mice and rats by hemorrhagic fever with renal syndrome (HFRS) virus.

Newborn mice and rats were inoculated intracerebrally (ic) or intraperitoneally (ip) with Hantaan virus (76-118 strain) or HFRS-related virus (B-1 strain). The mortality and the influence on the increase of body weight in newborn mice were higher in the groups infected with the 76-118 strain than in the groups infected with the B-1 strain, while the B-1 strain was more virulent in rats than the 76-118 strain. Virus isolation from rats inoculated with either strain was attempted 7 and 11 weeks after inoculation. Virus could be isolated from various organs of rats infected with the B-1 strain, while it was recovered from only the brain and lungs of rats infected with the 76-118 strain. Viral antigen was readily detected in various organs of rats infected with the B-1 strain, but the amount and distribution of antigens were less in rats infected with the 76-118 strain. Our results suggest that the virulence of HFRS-related virus is variable, depending on the species of infected animals as well as on the virus strains. The virus also persists in the injected animals with high titers of antibodies for at least 11 weeks.