The pathogenesis of respiratory syncytial virus infection in infant ferrets.

The infant ferret is susceptible to respiratory syncytial virus infection in both the upper and lower respiratory tracts. In the nose, viral replication is restricted to the surface respiratory epithelium in the nasal passages and turbinates. In the lungs, viral replication is of a lower order of magnitude and is localized in the alveolar cells. The pattern of viral replication in nasal tissues is independent of the age of the animal at infection, whereas the pattern in lung tissues shows a striking age dependence, with viral replication progressively decreasing as a function of age. Thes age dependence appears to be due to an intrinsic age-related mechanism yet to be defined. We feel that the infant ferret is an acceptable model for the study of respiratory syncytial virus disease and that the study of age dependence observed in ferrets may allow elucidation of the mechanisms involved in the age dependence seen in humans.