The occurrence of virus, interferon, and circulating antibodies in mice after experimental infection with Junin virus

Summary

Groups of white mice 3 to 30 days old were inoculated intracerebrally or intraperitoneally with Junin virus, the etiological agent of argentine hemorrhagic fever. Samples of brain and blood were taken at different intervals after inoculation to study the presence of virus, interferon and neutralizing antibodies. Mice increased its resistance to Junin virus with age, regardless the route of inoculation. When inoculated by intracerebral route, mortality reached 100% in 5 to 10 days old mice, decreasing to 7% by the age of 30 days. Virus was detected in the brain of 5–10 days old mice from the 3rd day on until death (11th day) occurred; in older groups of mice virus was no longer detectable by the 10th day after infection. Generally interferon (IF) in brain roughly paralleled the virus curve. Viremia was only detected in 5 days old animals on the 4th day after infection. Circulating IF was found from the 2nd day on in approximately similar levels in all cases. Neutralizing antibodies appeared late, not before the 20th day p. i. and therefore could be only detected in surviving 15 to 30 days old mice.

When inoculated by intraperitoneal route mortality was 100% in 24 hours old mice, decreasing to 5% by the age of 6 days. Only in the 3 days old group, virus was briefly detected in brain on the 5th day; but neither in this group nor in the olders an interfering activity in this organ could be demonstrated. No viremia or circulating antibodies were detected in any animal during the period of observation. However circulating IF persisted from 20 hours on in all age groups, suggesting that virus multiplication did occur.