Treatment of parainfluenza virus type 3 bronchiolitis and pneumonia in a cotton rat model using topical antibody and glucocorticosteroid.

Treatment of parainfluenza virus type 3 bronchiolitis and pneumonia in the cotton rat using topical IgG cleared infectious virus within 24 h but did not reduce pulmonary pathology. Treatment with topical triamcinolone acetonide dramatically reduced pathology but increased virus titers >10-fold. Combined therapy, however, demonstrated both favorable effects. Animals treated 3,4, and 5 days after infection showed a rebound of lung lesions to levels of untreated animals without reappearance of virus, but treatment through 8 days resulted in virus-free lungs without rebound of lesions. There was no difference in response to rechallenge 21 days after the original infection between treated and untreated animals. Combined antiviral and antiinflammatory therapy looks promising for viral bronchiolitis and pneumonia, but further questions relating to mechanism of action and to range of infections that can be treated in this fashion will need to be answered in animal models.