Antigenic role of the endosymbionts of filarial nematodes: IgG response against the Wolbachia surface protein in cats infected with Dirofilaria immitis

Filarial nematodes harbour intracellular endosymbiotic bacteria, which have been assigned to the genus Wolbachia. These bacteria appear to play an imp ortant role in the pathogenesis of filarial diseases through their lipopoly saccharides. In view of the presence of Wolbachia endosymbionts in the body of filarial nematodes, one might also expect that proteins from these bact eria play an antigenic role in humans and animals affected by filariases. T o lest this hypothesis, we produced in recombinant form the surface protein WSP and a portion of the cell-cycle protein FTSZ from the Wolbachia of Dir ofilaria immitis. Western immunoblot assays were then performed using cat s era to test the immunogenicity of these proteins. Sera were collected from owners' cats, which were either sero-negative or sere-positive for D. immit is and from cats before and after experimental infection with D. immitis. F TSZ was recognized in Western blots by sera from both positive and negative cats and from both uninfected and experimentally infected cars. WSP was re cognized only by sera from positive cats and from cats experimentally infec ted with D. immitis; this protein was not recognized by sera from negative cats and from cats before experimental infection with D. immitis. The resul ts of Western blot assays on WSP thus support the hypothesis that infection with filarial nematodes induces the production of antibodies against Wolba chia proteins.