Parasitology


Research Article

Reduced genetic variability within coding and non-coding regions of the Echinococcus multilocularis genome


K. L. HAAG a1 , A. ZAHA a2 , A. M. ARAÚJO a1 and B. GOTTSTEIN a3
a1 Departamento de Genética, Universidade Federal do Rio Grande do Sul, Caixa Postal 15053, Porto Alegre 91501-970, Brazil
a2 Departamento de Biotecnologia, Universidade Federal do Rio Grande do Sul, Caixa Postal 15005, Porto Alegre, 91501-970, Brazil
a3 Institute of Parasitology, University of Berne, Langasstrasse 122, PO Box 8466, Berne, CH-3001, Switzerland

Abstract

Echinococcus multilocularis, a vulpine intestinal tapeworm, is the causative agent of alveolar echinococosis in humans, one of the most severe and lethal parasitic infections in man. To date, there is very little knowledge about the genetical polymorphism of this parasite. To assess sequence polymorphism, we analysed a sample of 33 E. multilocularis 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 among genotypes of E. multilocularis were, in general, 10 times lower than among the recognized different strains of E. granulosus, we suggest that the conventional classification of the former species in 2 separated strains (European and North American) should be reviewed.

(Received April 2 1997)
(Revised May 21 1997)
(Accepted May 21 1997)

Key Words: Echinococcus multilocularis; SSCP; strain; genetic variability.

Correspondence:

Corresponding author. Departamento de Genética, Universidade Federal do Rio Grande do Sul, Caixa Postal 15053, 91501-970, Porto Alegre, Brazil. Tel: 0055 51 316 6717. Fax: 0055 51 319 2011. E-mail: karenha@voyager.com.br



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