Characteristic band pattern in western blots for specific detection of anti-Trichinella spiralis antibodies in different host species

Abstract

Abstract Western blot (Wb) is considered to be the gold standard test for Trichinella infection serology, since this method allows specific Trichinella antigens to be distinguished from cross-reactive antigens. This is not the case with widely used antibody assay techniques - indirect immunofluorescence and ELISA - which are sensitive, but subject to crossreactions that make the interpretation of weakly positive results difficult. Application of Trichinella spiralis muscle larvae excretory-secretory (ES) antigens for the specific antibody detection in ELISA resulted in improved specificity compared to that of crude worm extract that was previously in use, but since production of ES has not yet been standardized, differences among laboratories occur. For this reason, the Wb profile of serum samples from different T. spiralis infected host species: human, horse, swine and dog, was investigated in the Serbian National Reference Laboratory for Trichinellosis (NRLT). The common feature of the obtained Wb profiles was the appearance of a triad of bands with molecular masses (Mw) of 45, 49, and 53 kDa. The very same triad was recognized by a monoclonal antibody (mAb) 7C2C5 specific for an immunodominant epitope unique to the muscle larvae stage of all species in the genus Trichinella. Inhibition studies confirmed that mAb and anti-Trichinella antibodies from sera competed for the same parasite epitope. Based on the obtained results, the NRLT introduced the recognition of the above mention triad as the basis for specific anti-Trichinella antibodies detection in the sera of infected hosts.