Pathology and immunohistochemistry of callitrichid hepatitis, an emerging disease of captive New World primates caused by lymphocytic choriomeningitis virus.

Callitrichid hepatitis is an arenavirus infection that recently emerged as a highly fatal disease of New World primates in the Callitrichidae family. As we previously reported, these primates develop hepatitis after contact with mice that are infected with variants of LCMV (LVMCCH), recently determined to have 86% identity with GC-P gene of the Armstrong and Western strains of LCMV. Here, we describe the histopathological lesions and tissue localization of viral antigens in confirmed cases of callitrichid hepatitis from recent outbreaks in two U.S. zoos. The liver in marmosets and tamarins with fatal infections consistently showed degeneration, necrosis, and inflammation, with variable involvement of the spleen, lymph nodes, adrenal glands, intestine, pancreas, and central nervous system. Lymphocytic choriomeningitis virus antigens were identified immunohistochemically in necrotic foci in these organs as well as in nondegenerating areas in lungs, kidney, urinary bladder, brain, and testes. The multi-organ tropism and histological pattern of LCMV infection in marmosets and tamarins are similar to those reported for the highly virulent arenavirus that causes Lassa fever in humans. Comparative studies of callitrichid hepatitis and Lassa fever would therefore be mutually beneficial for human and nonhuman primate medicine.