Kinetics of specific humoral immune response of mice infected with low doses of Trichinella spiralis, T. britovi, and T. pseudospiralis larvae

The specific humoral immune response of the host (mouse) to the infection with low doses of larvae of encapsulating (Trichinella spiralis, T. britovi) and non-encapsulating (T. pseudospiralis) species was studied. Mice were experimentally infected with 10 muscle larvae of the parasite to simulate natural conditions of the infection in rodents, important reservoirs of trichinellosis. The low infective dose of T. spiralis and T. britovi did not evoke an increased specific IgM response, which is typical for the acute infection. Only T. pseudospiralis induced a higher specific IgM level in the intestinal phase of the infection, till day 30 p.i. The low infective dose of T. spiralis larvae stimulated a specific IgG1 production from day 20 p.i. with a strong increase on day 45 p.i., but T. britovi infection on day 60 p.i. Specific IgG1 antibodies were not detected in T. pseudospiralis infection. The production of IgG2a and IgG2b antibodies was again earlier and more expressive in T. spiralis infection from day 45 p.i., in contrast to T. britovi, where these antibodies were increased on day 60 p.i. Only IgG2b isotype was detected in T. pseudospiralis infection on days 45 and 60 p.i., however in very low values in comparison with encapsulating species.

Results conclude the low infective dose of T. spiralis, T. britovi, and T. pseudospiralis induced a late seroconversion in infected mice. T. spiralis caused earlier and more intensive specific antibody response, from day 45 p.i, when antigens from newborn and muscle larvae were accumulated, on the contrary to T. britovi and T. pseudospiralis, which induced specific antibody response from day 60 p.i.