REDUCED GENETIC-VARIABILITY WITHIN CODING AND NONCODING REGIONS OF THE ECHINOCOCCUS-MULTILOCULARIS GENOME

Echinococcus multilocularis, a vulpine intestinal tapeworm, is the cau sative agent of alveolar echinococosis in humans, one of the most seve re and lethal parasitic infections in man. To date, there is very litt le knowledge about the genetical polymorphism of this parasite. To ass ess sequence polymorphism, we analysed a sample of 33 E. multiloculari s isolates from Europe, North America and Asia by PCR-SSCP followed by nucleotide sequencing. This assessment was performed comparatively to sheep, cattle and pig E. granulosus strains. Coding (nuclear antigen B and mitochondrial NADH dehydrogenase genes) and non-coding (introns of actin and homeobox-containing genes) regions of the parasite genome were chosen as targets. Since the estimated nucleotide diversity amon g genotypes of E. multilocularis were, in general, 10 times lower than among the recognized different strains of E. granulosus, we suggest t hat the conventional classification of the former species in 2 separat ed strains (European and North American) should be reviewed.