[Effect of cyclophosphamide on experimental infection of rats with 2 strains of the Junin virus].

The course of viral infection in rats of several ages after intracerebral inoculation with two strains of Junin virus, as well as the effect of an immunosuppressor was studied. The survival rate in 2-day-old rats was 95%, which fell to 45% in cyclophosphamide-treated infected animals (Figure 1a). However, barely 5% of these rats inoculated with the XJCl3 strain survived, while the cyclophosphamide suppressive treatment increased the rate to 36% (Figure 1b). This contrasting behaviour suggested that the XJ strain produces a subclinical infection in 2-day-old rats and the host immune mechanisms are responsible for recovery from the viral infection. Adequate immunosuppression converts sublethal experimental infections into lethal infection, accompanied by persistent viral replication in the target organ (brain) and suppression of anti-viral antibodies (Figure 2a). On the other hand, the inoculation of 2-day-old rats with the XJCl3 Junin virus may give rise to an immunopathology avoidable by CY treatment. In 10-day-old rats both strains of Junin virus caused a direct pathology, not modified by CY treatment (Table 3). This treatment failed to change susceptibility or virus concentration in the brain, but specific antibodies were considerably reduced. In the case of 26-day-old rats, there was total resistance to viral infection which remained unchanged after CY treatment.