Pathogenicity of an attenuated strain (XJCl3) of Junin virus. Morphological and virological studies in experimentally infected guinea pigs.

Infection of guinea pigs with an attenuated strain of Junin virus (JV) produced 16% mortality between days 17 and 27 postinfection (p.i.). The morphological study showed a marked pancreatitis between days 6 and 23 p.i. and meningoencephalitis between days 17 and 20 p.i. in a large proportion of the animals. These lesions were coincident with the presence of JV antigenic determinants in the pancreatic acinar cells, neurons and blood vessels of the brain. Infectious virus could be isolated from lymph nodes, spleen, bone marrow, lungs, adrenal glands, and brain. The lesions appeared to be reversible, as they were absent in animals studied after day 64 p.i. Meningoencephalitis, present in all animals dying spontaneously, appeared to be the most important cause of death. Our observations indicate that more accurate markers of virulence must be investigated in the search for attenuated strains of JV as potential vaccine candidates for Argentine hemorrhagic fever.