The guinea pig as a model for the study of maternal immunization against respiratory syncytial virus infections in infancy.

Maternal immunization might protect infants from severe disease due to respiratory syncytial virus (RSV). Guinea pigs are susceptible to infections with RSV and transfer antibodies to their offspring prenatally. Pregnant guinea pigs were immunized by infection with RSV and their offspring were challenged intranasally with RSV. Pulmonary viral replication was compared among the pups born to immunized mothers (group A) and the pups from nonimmune mothers (group B) in two studies. Mean (+/-SD) log10 virus titers were, in study 1, group A, 2.3 +/- 0.8 pfu/g of lung (n = 10); group B, 3.6 +/- 1.5 pfu/g (n = 13) (P = .0058); and study 2, group A, < 1.69 pfu/g (n = 8); group B, 3.4 +/- 0.9 pfu/g (n = 6) (P = .0002). Thus, immunization of pregnant guinea pigs resulted in a significant reduction in viral replication in the lungs of their offspring. Guinea pigs should be useful for the study of maternal immunization against RSV.