Study on Histopathologic Changes of Suckling Rats Inoculated with Hantaan Virus

ABSTRACT

Hantaan and related viruses have been implicated as causative agents for a diverse group of human diseases known collectively as "hemorrhagic fevers with renal syndrome" (HFRS). Outbred SD rats obtained within 24 hours after birth were inoculated by intracerebral (the first group) or intramuscular routes (the second group) with 10(9.5)/ml DL50 of Hantaan seed virus suspension in 0.02 ml and 0.1 ml, respectively. Brain, lung, liver, kidney and spleen were used for virus antigen detection by immunofluorecence and histopathologic examination. In the first group, immunofluorescent intensity of virus antigen was increased in all organs (especially brain) and persisted until time of death(day 9). The histopathologic changes were relatively mild in brain and spleen and unremarkable in liver, lung and kidney. In the second group, immunofluorescent intensity of virus antigen was markedly increased in brain until time of death(day 17), but decreased in other organs. The histopathologic findings, such as meningoencephalitis, interstitial pneumonitis with focal hemorrhage, and lymphoid hyperplasia of splenic white pulp were much prominent compared to the first group. However, those of liver and kidney were unremarkable. The chronology of virologic and pathologic findings in Hantaan-infected suckling rats suggests a possible immune-mediated mechanism in disease pathogenesis.