Depressed immunity to a Salmonella typhimurium vaccine in mice experimentally parasitized by Taenia crassiceps.
To assess the immunological status of mice parasitized with Taenia crassiceps metacestodes, 6-month old female BALB/c mice experimentally parasitized with T. crassiceps and immunized with Salmonella typhimurium antigens were infected with S. typhimurium virulent bacilli (1.6 x LD50). Both T. crassiceps-parasitized and immunized and parasitized mice showed a very high susceptibility to infection (**P < 0.01) with higher bacteremia than control and immunized-control animals and produced a reduced IgG response to S. typhimurium, antigens (* P < 0.05). This indicates that T. crassiceps is able to preclude development of immunity to S. typhimurium, because appropriate antibody production to a heterologous antigenic stimulus did not take place, and the bacteremia results suggest the parasitosis altered the mononuclear phagocyte system. It has been demonstrated that Taenia solium metacestodes produce a small RNA molecule in culture which suppresses humoral and cellular responses against homologous antigens in mice. We propose that T. crassiceps may be actively synthesizing such a factor, apart from other simultaneously acting immunomodulatory mechanisms, to induce an immunosuppressed state favorable to its development in the host.
Rubio
M
M
Department of Immunology, UNAM, DF, Mexico.
Tato
P
P
Govezensky
T
T
Molinari
J L
JL
D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology; D016470:Bacteremia / Q000276:immunology; D001428:Bacterial Vaccines / Q000276:immunology*; D015153:Blotting, Western / Q000662:veterinary; D015169:Colony Count, Microbial / Q000662:veterinary; D004306:Dose-Response Relationship, Immunologic; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000097:blood; D051379:Mice; D008807:Mice, Inbred BALB C; D012481:Salmonella Infections, Animal / Q000276:immunology* / Q000517:prevention & control; D012486:Salmonella typhimurium / Q000276:immunology* / Q000472:pathogenicity; D013621:Taenia / Q000276:immunology / Q000502:physiology*; D013622:Taeniasis / Q000276:immunology*
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D007074:Immunoglobulin G