PATHOLOGICAL AND VIROLOGICAL FEATURES OF ARENAVIRUS DISEASE IN GUINEA-PIGS - COMPARISON OF 2 PICHINDE VIRUS-STRAINS

A guinea pig passage-adapted strain of the arenavirus Pichinde (adPIC) is highly virulent in inbred guinea pigs, whereas the related strain PIC3739 is attenuated. Both viruses were macrophage tropic and infecte d peritoneal, splenic, liver, and alveolar macrophages during experime ntal Pichinde virus infection. Infection with the virulent strain was associated with unlimited viral replication in the face of exaggerated delayed-type hypersensitivity response, manifested by the macrophage disappearance reaction. Histopathological lesions unique to adPIC-infe cted guinea pigs included intestinal villus blunting with mucosal infi ltration by pyknotic debrisladen macrophages and apoptosis of crypt ep ithelial cells. Splenic red pulp necrosis was also significantly assoc iated with adPIC infection but not PIC3739 infection. These findings m ay provide clues to the pathogenesis of a group of poorly understood h uman viral hemorrhagic fevers.