Mucosal immunity and viral infections

The mucosal surfaces are the first portals of entry for most infectious age nts. among which respiratory and intestinal viruses are of greatest epidemi ological importance. To combat these infections, the immune system uses uns pecific and specific mechanisms. Unspecific responses include the productio n of virus-induced cytokines, such as type 1 interferons and natural killer (NK) cell activity, while specific immune responses mainly depend on cytot oxic T cells. which are important especially in the early course of a viral infection, and on antibodies. At the mucosal sites, antiviral secretory Ig A antibodies play a major role in clearing viral infections and preventing or modifying disease after re-exposure. Passive transfer of virus-specific antibodies has been used in experimental and clinical settings to prevent o r treat viral mucosal infections. In the future. the development of new muc osal vaccines promises to have the strongest impact on the epidemiology of viral infections.