The availability of restriction fragment length polymorphisms (RFLPs) would be useful
for studying the extent of diversity among morpholgically indistinguishable populations of
filarial parasites. Such polymorphisms may be useful in correlating various physiological and
clinical differences with parasite heterogeneity. In order to identify such RFLPs, we isolated
DNA from microfilaria of 6 filarial species (Acanthocheilonema viteae, Brugia malayi, Brugia
pahangi, Dirofilaria immitis, Litomosoides carinii and Setaria digitatum), digested the DNA
with several restriction endonucleases, prepared Southern blots and probed with 32P-labelled
DSA probes. The patterns of fragments generated using two restriction endonucleases,
Mbo I and Taq I, in combination with two probes, rDNA from the free-living soil nematode
Caenorhabditis elegans, and pBM103, an anonymous DNA probe from B. malayi,
unequivocally distinguish between all 6 of the species. To ensure that the differences we
observed between the species represent true interspecies variation rather than fortuitous
individual variations we analysed DNA from several individual B. malayi and B. pahangi
worms. The individual B. malayi worms demonstrated restriction profiles that were
invariant, as did the individual B. pahangi worms, demonstrating that the differences we
observed were true interspecies variations
