We have developed a mass production system for the 46.5k protective antigen(46.5kPA) of Erysipelothrix rhusiopathiae by using the Bacillues brevis-pNU21 system. Intranasal immunization with the 46.5kPA subunit vaccine mixed with recombinant low toxic mutant protein of heat labile toxin (rmLT), elicited significantly higher levels of specific IgA antibodies in the nasal secretions and of specific IgG antibodies in serum against the bacterial antigens, in comparison with the vaccine alone. Furthermore, pigs intranasally immunized with the vaccine plus rmLT were significantly protected from challenge infection with a virulent strain of Erysipelothrix rhusiopathiae via the intradermal route. These findings highlight the potential usefulness of 46.5kPA admixed with rmLT as a mucosal subunit vaccine for swine erysipelas. (Department of Bacteriology and Parasitology TEL +81-298-38-7737)
