Immunization against geographical isolates of Trichinella spiralis in mice.

Partially purified antigen preparations from six isolates of Trichinella spiralis were used to immunize mice. Immunogenicity of the antigens was assessed in terms of antibody and lymphocyte responses and ability to stimulate protective immunity against challenge. Isolate antigens showed considerable cross-reactivity, and all elicited protective responses. Two major patterns of immunizing ability could be distinguished: (a) isolates that immunized well against heterologous challenge and elicited good immunity in London isolate-immunized mice (C-76 and Laso), and (b) isolates that immunized poorly against heterologous challenge and were least effective in London isolate-immunized mice (GM-1 and Mad-83). The immunogenicity of one isolate (C-76) was markedly greater than the others, inducing rapid loss in unvaccinated mice, almost complete protection in London isolate-immunized mice, and immunity in London isolate-challenged mice equivalent to the homologous antigen. These variations in immunogenicity, cross-reactivity and immunizing ability are discussed in terms of constraints that may operate against the development and use of vaccines against parasites that are widely distributed geographically.