Five restriction endonucleases were used to digest genomic DNA from 5 isolates of Trichinella spiralis obtained from Changchun

Tianjin

Xian

Henan and Yunnan. All the isolates were secured from pigs except the Changchun strain which came from dog. The DNA fragments digested by endonuclease were separated by agarose gel electrophoresis. The Changchun isolate had a EcoRI band at 1. 12kb and a DraI band at 1. 97kb which were unique to this isolate. A cloned specific repetitive DNA sequence （1. 12kb） from the Changchun strain was selected to prepare a probe for the Southern blotting of EcoRI restriction DNA fragments for the 5 isolates. The 1.12kb hybridizing band did not appear except in the Changchun isolate.These results seem to indicate that there are differences between the isolates obtained from hosts in different geographical regions.