Antibody-mediated protection against respiratory viral infection.

Effective antibody responses are critical for protection against many human pathogens, including those with tropism for the respiratory tract (RT). Systemic immunoglobulin (Ig)G responses as well as mucosal IgA responses play complementary roles in protection against RT infections, and induction of a tissue-specific, isotype-appropriate humoral response is central to successful vaccination strategies. For respiratory virus infections in which current vaccines are either not available or not fully effective, antibody-mediated therapies may provide a viable treatment option. Prophylactic administration of polyclonal or monoclonal antibodies shows the best clinical efficacy, whereas therapeutic administration of antibodies after infection can also be highly protective but is greatly dependent on timing; efficacy declines soon after onset of disease symptoms. Further understanding of the mechanisms underlying antibody-mediated protection against respiratory virus infections may lead to improved immunization strategies as well as more effective antibody-based therapeutics.