Background Viral respiratory tract infections have been previously considered to be associated with induction of allergic sensitization.
Objective and Methods In order to investigate this relationship in an animal model, guinea-pigs were inoculated intranasally with Parainfluenza-3-(PI-3) virus (n= 16) or virus-free culture medium (controls, n= 12), sensitized at day 4 with inhaled ovalbumin (OA) and challenged 3 weeks later with inhaled OA using specific bronchial provocation testing with body piethysmographic measurement of compressed air (CA). Furthermore, specific anti-OA-IgGl-antibodies in serum before challenge were determined by enzyme hnked immunosorbent assay (ELISA). For investigation of airway epithelium permeability horseradish peroxidase (HRP) was inhaled at day 4 after inoculation by six animals, and HRP serum concentrations were determined by a direct ELISA 30 min after inhalation.
Results PI-3 infected animals were found to be significantly more sensitized to OA compared with controls, with higher CA values (P < 0.001) on specific bronchial provocation and with increased specific anti-OA-IgGl titers. Serum-HRP concentrations were about 20 times higher in the infected animals compared with controls. PI-3 infected and sham-infected animals had comparable bronchial reactions on specific provocation with OA when sensitized systemically.
Conclusions We conclude that viral respiratory tract infection with PI-3 virus enhances inhaiative allergic sensitization in the guinea-pig. Increased mucosal permeability to antigens may be an important pathophysiological mechanism.