Immunological responses in the mouse host to a cloned antigen of Taenia crassiceps

Adult female Swiss-Webster mice were immunized either intraperitoneally (IP) or subcutaneously (SQ) with cyst fluid or a genetically engineered fusion protein, Taenia crassiceps antigen 2-maltose binding protein (TCA2-MBP) from Taenia crassiceps metacestodes, or with live, non-budding cysts SQ, and then challenged IP with T. crassiceps metacestodes and necropsied 9 weeks later. Numbers of peripheral blood eosinophils were increased after IP immunization, but were not increased after SQ immunization or with SQ cysts given before the challenge infection. Eosinophil numbers gradually decreased over the course of the experiment, and were not found in increased numbers in the blood or peritoneal cavity at necropsy. Antigen-specific antibody responses were seen at day 14 or 28 in IP and SQ immunized groups: IgG1 and IgG3 isotypes continued to increase over the course of the experiment. A significant protective response was induced by immunization with the cyst fluid (15 +/- 4, X +/- SE recovered larvae) or the TCA2-MBP (22 +/- 12) given IP, but not SQ (122 +/- 36; 207 +/- 53, respectively) as measured by the numbers of larvae recovered at necropsy. Live cysts given SQ resulted in reduced numbers of cysts in the peritoneal cavity (188 +/- 66), but was not as effective as cyst fluid or TCA2-MBP given IP. Locally (IP) induced immune responses may be involved in the development of the protective response to a challenge infection with T. crassiceps metacestodes.