Human serum antibodies against shared antigens of different stages of Trichinella spiralis: relevance of glycan and protein epitopes

Taking into account that antibodies against the surface antigens of newborn larvae (anti-NBL Abs) present in sera from individuals with chronic trichinellosis recognize antigenic determinants of the excretory-secretory muscle larva products (ML-ESP), and that these products are mainly glycoproteins, the aim of this work was to assess the frequency of anti-NBL Abs in sera from individuals with acute and chronic trichinellosis, to analyse the relevance of glycan and protein epitopes of the ML-ESP in the cross-reactivity phenomenon, and its correlation with the host's serum response towards these products. Anti-NBL surface Abs were determined in sera by indirect immunofluorescence. The degree of recognition by serum and purified anti-NBL Abs was evaluated comparatively before and after chemical deglycosylation of ML-ESP by immunoelectrotransfer blot assay. Results showed that 64% of the sera from individuals with acute trichinellosis and 35% of those belonging to the chronic phase had anti-NBL Abs, and also that the protein epitopes are the major ones responsible for the cross-reactivity phenomenon involving the ML-ESP and the NBL surface during both phases of the infection, while glycan epitopes are immunodominant in the stimulation of the host's immune system. A modulatory phenomenon in the immune response generated towards Trichinella spiralis NBL driven by the ML-ESP is postulated.