Circulating interferon in the guinea pig infected with the XJ, prototype Junin virus strain.

The interferon (IFN) induction capacity of the XJ prototype strain of Junín virus (JV) was investigated in the guinea pig model. Circulating alpha IFN was detected in 50% of the animals from days 2 to 9 postinfection (pi) and in 100% at day 11 pi, when all animals were in the premortem stage. Individual levels ranged from 20 to 1,280 guinea pig IFN units (GPIFNU)/ml. A correlation between XJ strain virulence and IFN titers was recorded. A possible role of IFN as a pathogenic factor in the outcome of the disease is discussed.