Argentine hemorrhagic fever: a biologic marker.

Mortality rates and viral replication in blood and brains of Wistar rats between 6 h and 26 days of age inoculated with two strains of Junin virus of different virulence were compared. Viral growth curves in brains showed no differences between strains. However, differences in mortality rates were significant among rats between 1 and 3 days of age. When the intracerebral (i.c.) route was used, high mortality rates were induced by the attenuated XJC13 strain and low mortality rates were induced by the pathogenic XJ strain. On the other hand, when the intraperitoneal or subcutaneous route was used, mortality rates were reversed: low for the attenuated strain and high for the pathogenic one. The use of different doses of each virus and the application of various routes of inoculation in 2-day-old rats showed that 10(3) TCID50 by the i.c. route resulted in the greatest difference in mortality rates.