Influence of Trichinella spiralis infective dose on the level of antibodies, circulating antigens and circulating immune complexes in rats

The object of present study is to explain the late appearance of specific T . spiralis antibodies in humans and animals after infection, as well as exa mine the dynamics of antibodies, circulating antigens and immune complexes in parallel, depending on the infective dose. The immunological parameters were investigated from the 1st day post infection (dpi) until the 6th month post infection (mpi). The rats were infected with different doses of T. sp iralis larvae: 500, 700, 1000, 1200, 1900 and 2500. They were examined for presence of specific antibodies to larval metabolic and somatic antigens se parately, circulating antigens and circulating immune complexes. The circulating antigens were present in rat sera from the 3rd to the 30th dpi. The level of circulating antigens was the highest at the 5th dpi and w as dependent on infective dose being the highest in sera of rats infected w ith 2500 larvae. Specific antibodies of both classes were observed from day 20 pi till the end of the experiment. Ige antibodies showed a higher level than IgM. The level of both classes of antibodies was higher when examined with larval metabolic antigen than with the somatic one and was the highes t in sera of rats infected with 1900 larvae. The peak levels of circulating immune complexes were detected between 4th a nd 15th dpi. The investigations showed the presence of T. spiralis antigens as well specific antibodies of IgM and IgG in circulating immune complexes .