Early protection to Junín virus of guinea pig with an attenuated Junín virus strain.

Inoculation of guinea pigs with attenuated XJO Junín virus (JV) strain confers protection against challenge with pathogenic XJ-JV strain starting as early as 3 days post infection (p.i.). The protection increased continuously up to 100% by 30 days p.i. Neither stimulation of non-specific cell mediated mechanisms by previous BCG sensitization nor circulating interferon (IFN) seemed essential for such protection. The early detection of the virus in guinea pig organs considered the site of primary JV multiplication suggests that early resistance phenomenon was attributed mainly to direct viral interference.