Effects of vaccination on cytomegalovirus-associated interstitial pneumonia in strain 2 guinea pigs.

The pathogenesis and prevention of generalized infection and interstitial pneumonia due to cytomegalovirus (CMV) in inbred strain 2 guinea pigs were investigated. Eighteen animals inoculated with approximately 10(7) 50% tissue culture infective doses of virulent salivary gland-passaged guinea pig CMV (GPCMV-SG) developed generalized, viremic CMV infections, and 44% of the animals died. Most (68%) cocultivated tissues showed CMV infection, including lungs, which demonstrated severe bilateral interstitial pneumonia. Guinea pigs inoculated with live tissue culture-passaged GPCMV (GPCMV-TC) vaccine developed mild, nonlethal, generalized CMV infections and minimal histopathologic changes in infected tissues, including lungs. After challenge of 19 GPCMV-TC-vaccinated animals with GPCMV-SG, viremia was detectable in two (11%); CMV was detected in 15% of cocultivated tissues and rarely in lungs. Although vaccinated animals showed histologic evidence of interstitial pneumonia after challenge, none died. Strain 2 guinea pigs are useful for studies of pathogenesis and prevention of generalized CMV infection, particularly CMV-associated interstitial pneumonia.