Abstract: This invention relates to the use of genetically modified, non-pathogenic bacteria on the mucosal surfaces of a host to inhibit infection by specific viruses at mucosal surfaces. Specifically, non-pathogenic bacteria are modified to acquire the capacity to bind and functionally inactivate specific viruses. Further manipulations are devised to ensure the persistent colonization of said bacteria on the desired mucosal surface of a host. The capacity to bind a pathogen by said bacteria may be accomplished through the expression on the bacterial surface of a molecule, either a polypeptide or carbohydrate moiety, which binds specifically to a molecule on the target virus. Such a capacity may be conferred upon said bacteria via genetic manipulations.