Biological and genetic characteristics of two Trichinella isolates in China; comparison with European species.

The most recent taxonomic revision in Trichinella genus included 10 taxa. Trichinella spiralis (Ts) is a thoroughly studied species but most of the isolates came from the Europe or American continents. Few information is available from China about the Trichinella isolates and their diversity. In this report two Chinese isolates were characterized and compared with European strains. The in vitro release of newborn larvae (NBL) was determined for the two species. NBL is observed in supernatant of cell culture after adults purification on day 4 post infection (pi) with Ts, and on day 5 pi with Trichinella nativa (Tna). A new parameter was thus proposed to characterize Trichinella strains. Restriction fragment length polymorphism (RFLP) of genomic DNA and random amplified polymorphic cDNA (RAPD) were used to define genetic variability among different isolates. Species specific pattern could be obtained with RAPD but it was far more difficult to get geographical markers for Trichinella using these methods. A low genetic variability in Trichinella species (i.e. a strong "clonality") is suggested.