Nucleotide sequences of DNA fragments of Encephalitozoon cuniculi amplified by polymerase chain reaction with primers regarded as specific for Echinococcus.

Encephalitozoon-like spores were separated from a human echinococcal liver lesion, which was caused by Echinococcus multilocularis. They were found to fall into the species Encephalitozoon cuniculi, which was shown to have En. cuniculi-specific DNA by way of polymerase chain reaction (PCR). We also used PCR to genetically discriminate between the En. cuniculi spores and the Ec. multilocularis larvae. Two primer sets, known to be specific for Echinococcus, were examined. These primers were expected to work normally when the two quite different DNA preparations were tested as templates, i.e. only Echinococcus DNA could give a positive signal in the PCR tests. However, it was found that the two Echinococcus-specific primer sets could amplify not only Ec. multilocularis DNA, but also En. cuniculi spore DNA. We then tried to determine the order of nucleotides in the Echinococcus-specific primers-amplified En. cuniculi PCR products and compared the determined sequences with those of Ec. multilocularis. The results clearly indicated that sequencing made little difference between En. cuniculi and Ec. multilocularis.