M. Rubio et al., DEPRESSED IMMUNITY TO A SALMONELLA-TYPHIMURIUM VACCINE IN MICE EXPERIMENTALLY PARASITIZED BY TAENIA-CRASSICEPS, Veterinary parasitology, 74(2-4), 1998, pp. 179-189
To assess the immunological status of mice parasitized with Taenia cra
ssiceps metacestodes. 6-month old female BALB/c mice experimentally pa
rasitized with T. crassiceps and immunized with Salmonella typhimurium
antigens were infected with S. typhimurium virulent bacilli (1.6 x LD
50). Both T. crassiceps-parasitized and immunized and parasitized mice
showed a very high susceptibility to infection ( * P < 0.01) with hi
gher bacteremia than control and immunized-control animals and produce
d a reduced IgG response to S. typhimurium antigens ( P < 0.05). This
indicates that T. crassiceps is able to preclude development of immun
ity to S. typhimurium, because appropriate antibody production to a he
terologous antigenic stimulus did not take place, and the bacteremia r
esults suggest the parasitosis altered the mononuclear phagocyte syste
m. It has been demonstrated that Taenia solium metacestodes produce a
small RNA molecule in culture which suppresses humoral and cellular re
sponses against homologous antigens in mice. We propose that T. crassi
ceps may be actively synthesizing such a factor, apart from other simu
ltaneously acting immunomodulatory mechanisms, to induce an immunosupp
ressed state favorable to its development in the host. (C) 1998 Elsevi
er Science B.V.