MOLECULAR DIFFERENCES BETWEEN SEVERAL SPECIES OF STRONGYLOIDES AND COMPARISON OF SELECTED ISOLATES OF S-STERCORALIS USING A POLYMERASE CHAIN REACTION-LINKED RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM APPROACH

The relationships between the parasitic nematodes of medical importanc e belonging to the genus Strongyloides was studied using a polymerase chain reaction (PCR)-linked restriction fragment length polymorphism a pproach. We used several human and dog isolates of S. stercoralis, a m onkey isolate of S. fulleborni, and S. ratti, a rodent parasite. The m olecular analysis was based on amplification of the internal transcrib ed spacer and the 5' portion of the 23S-like rRNA gene followed by res triction enzyme digests. The length of the PCR product was specific to each species and varied around 1.5 kilobase pairs. Using nine restric tion enzymes, we were able to analyze both interspecific and intraspec ific variations. With four restriction enzymes (Taq I, Dde I, Dra I, a nd Mwo I), human isolates of S. stercoralis from different parts of th e world showed identical patterns and could be differentiated from the dog isolate of S. stercoralis. Interspecific differences were readily observed with these and other enzymes. In addition to providing new i nformation on the genomic characteristics of Strongyloides parasites, the results suggest that this technique could be useful for diagnostic and epidemiologic investigations.