Expression of excretory and secretory protein genes of Trichinella at muscle stage differs before and after cyst formation.

By adapting a semi-quantitative reverse transcriptase-PCR (RT-PCR) method, we investigated kinetics of gene expression at different developmental stages of Trichinella spiralis and T. pseudospiralis. The analyzed genes included four kinds of excretory and secretory (ES) proteins, a heat shock protein (HSP) and a DNA binding protein and showed that T. spiralis and T. pseudospiralis expressed ES proteins in a stage-specific manner. The gene encoding a 43 kDa ES protein was expressed by muscle larvae, either pre-cyst or post-cyst larvae. The genes encoding: the 53 kDa ES protein of T. spiralis; 53 kDa ES protein of T. pseudospiralis; and 19.6 kDa ES protein of T. spiralis were expressed by post-cyst larvae and adult worms, but not expressed by pre-cyst larvae or newborn larvae. The results showed that pre-cyst larvae and post-cyst larvae are similar but different in the expression of 53 and 19.6 kDa ES proteins. On the other hand, genes of housekeeping proteins, such as HSP and the DNA binding protein, were expressed at all stages although there were some differences in the expression level.