Genomic variability within laboratory and wild isolates of the trichostrongyle mouse nematode Heligmosomoides polygyrus

PCR-RFLP techniques have been used to characterize wild and laboratory isol ates of the trichostrongyle nematode Heligmosomoides polygyrus from the woo d mouse Apodemus sylvaticus and the laboratory mouse Mus musculus respectiv ely. Both isolates can be distinguished by eight endonuclease digestions of the ITS region of the rDNA repeat namely, Alu I, Dde I, Hpa II, Hae III, H inf I, Hha I, Pvu II and Sal I. In two of the digests, Hinf I and Rsa I, a minor polymorphism was observed in the wild isolate of H. polygyrus which h as been cultured in laboratory-bred A. sylvaticus for several generations w hen compared with H. p. polygyrus from wild A. sylvaticus. A minor polymorp hism was also identified in further wild isolates of H. polygyrus collected from A. sylvaticus in a field site in Egham, Surrey. However no evidence o f polymorphism was observed in the laboratory isolate of H. polygyrus from the CD1 strain of M. musculus and the laboratory-bred A. sylvaticus. Reason s for this are discussed and further studies on the population genetics of H. polygyrus are suggested.