A repetitive DNA probe specific for a North American sylvatic genotype of Trichinella

A partial genomic DNA library constructed in pUC 13 using DNA from a sylvatic isolate of Trichinella spiralis (T. spiralis T5) was differentially screened with radiolabeled homologous genomic DNA and with DNA from T. spiralis T1. One clone was identified and designated pUPB-3.7 which, by slot blot and Southern blot analyses, reacted specifically with T. spiralis T5 DNA and did not cross-react with DNA from any other T. spiralis genotype. The 482-bp repetitive sequence which is 70% rich in A and T residues, comprises at least 2.7% of the parasite genome and can detect as little as 0.4 ng of DNA. When used to assess the prevalence of T. spiralis T5 in Indiana wildlife, DNA from 19 of 20 independently obtained sylvatic isolates reacted positively with the pUPB-3.7 probe indicating that within this geographical locality, T. spiralis T5 is the predominating genotype in wild mammals.