The unusual
sugar tyvelose is the immunodominant portion of the major larval
glycoprotein antigens of Trichinella spiralis, which play an important role in generating immunity against the intestinal stages of
infection. The possibility that the
tyvelose component itself may have a host- or parasite-protective role in the intestine was tested by following the outcome of challenge
infections in mice primed and boosted with
tyvelose-BSA, or in mice primed with
tyvelose-BSA before boosting with larval
antigen. Although antibody responses were raised against
tyvelose there was no evidence of protective immunity against the intestinal stages, as assessed by total adult worm recovery or by size and fecundity of female worms in immunized mice. Equally, priming with
tyvelose-BSA before boosting with larval
antigen had no effect on the expression of immunity against a challenge
infection. The predominant antibody isotype recorded in all immunized mice was
IgG1, suggesting the induction of type 2 T cell responses, and this was confirmed by
cytokine analysis, mesenteric node lymphocytes of all mice showing production of
IL-5 but not IFN-gamma. Clearly immunization with
tyvelose had no significant effect on T cell polarization. The data show that, with the experimental design employed, there was no evidence for a functional role of
tyvelose in either host- or parasite-protection during the intestinal phase of
infection.