Identification of Bartonella-specific immunodominant antigens recognized by the feline humoral immune system.

The seroreactivities of both naturally and experimentally infected cats to Bartonella henselae was examined. Serum samples collected weekly from nine cats experimentally infected with B. henselae LSU16 were tested by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis. The magnitude and isotype of the antibody response were investigated by ELISA. Western blot analysis allowed the identification of at least 24 Bartonella-specific antigens recognized by the cats during infection. Antibody titers to specific antigens, as determined by Western blot analysis, ranged from 10 to 640 and varied among the different antibody-antigen interactions. Absorption of sera from an experimentally infected cat, using whole cells and cell lysates of various Bartonella species and other bacteria that commonly colonize cats, supported the identification of those Bartonella-specific antigens recognized by the experimentally infected cats. Furthermore, a number of possible species- and type-specific antigens were identified. Finally, sera obtained from cats at local animal shelters were screened for the presence of antibodies directed against the Bartonella-specific bands identified in the experimentally infected cats. A number of Bartonella-specific antigens have been identified to which strong antibody responses are generated in both experimentally and naturally infected cats, some of which may be useful in diagnosing species- and/or type-specific infections. In addition, the results from these experiments will lead to the development of monoclonal antibodies targeted against those genus-, species-, and type-specific antigens.