Study of the Antigenic Relationships between Junín Virus, the Etiological Agent of Argentinian Hemorrhagic Fever, and Other Arthropod-Borne Viruses

Abstract

Summary Strains XJ, R and F of Junin virus, which were isolated by two different groups of investigators, have been compared for the first time and been found to be indistinguishable by complement-fixation test. Neutralization test comparisons are pending. Junin and Tacaribe virus from Trinidad have been shown to be closely related by complement-fixation test, although distinguishable on the basis of serum titers. In limited studies by neutralization test they were easily separable. It is of interest that sera from persons convalescing from Argentinian hemorrhagic fever fixed complement in the presence of Tacaribe antigen. No cross-reactions were observed between Junin complement-fixing antigens and immune sera for 139 other arthropod-borne viruses, or between Junin antisera and hemagglutinating antigens from 41 arboviruses. Junin antigens likewise failed to react by complement-fixation test with various non-arboviruses including encephalomyocarditis, mouse encephalomyelitis and several rickettsiae. From descriptions in the literature there appears to be a degree of clinical resemblance between Korean and Argentinian hemorrhagic fevers; sera from six human patients convalescing from the former failed to react with a Junin complement-fixing antigen. Junin antigens with consistently good complement-fixing titers between 1:32 and 1:128 were obtained by harvesting infected mouse brain tissue 7 or 8 days after inoculation. A growth curve study showed maximal virus titer at that time in the absence or near absence of signs of illness. Junin strain XJ, which originally was highly pathogenic for guinea pigs by the intraperitoneal route of inoculation, appeared to have lost its pathogenicity for guinea pigs by that route after about 40 passages in newborn mice.