Topical immunoprophylaxis of respiratory syncytial virus (RSV)-challenged mice with RSV-specific immune globulin.

The modulatory effects of passive antibody on viral replication, illness, and immunity were investigated in a murine model of respiratory syncytial virus (RSV) infection. Nasally administered RSV-specific immune globulin (RSVIG) given prophylactically in a large volume (100 microL) reduced illness and RSV replication in lung after primary challenge. However, passive antibody treatment diminished the host antibody response to primary RSV infection. This resulted in greater susceptibility to reinfection and an alteration in the composition of the immune response after rechallenge. RSV infection of lung during primary infection was necessary for complete protection of lung from RSV rechallenge. Nasal infection alone during primary infection was not sufficient to protect against RSV rechallenge of lung, suggesting that the immune responses in the murine system are compartmentalized. The influence of compartmentalized immunity and modulation of immune responses will be important considerations as new approaches for topical immunoprophylaxis of RSV are developed.