Parasitology



A microsatellite marker reveals population heterogeneity within human and animal genotypes of Cryptosporidium parvum


S. CACCIÒ a1c1, W. HOMAN a2, R. CAMILLI a1, G. TRALDI a3, T. KORTBEEK a4 and E. POZIO a1
a1 Laboratory of Parasitology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
a2 Microbiology Laboratory of Health Protection, National Institute of Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 Bilthoven, The Netherlands
a3 Faculty of Veterinary Medicine, University of Camerino, Camerino, Italy
a4 Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, National Institute of Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 Bilthoven, The Netherlands

Abstract

Isolates of the protozoan parasite Cryptosporidium parvum have been differentiated into 2 genotypes: genotype ‘H’, which is associated only with human infections, and genotype ‘C’, which is associated with both human and animal infections. To date, the analysis of polymorphisms of genes and of the small subunit ribosomal DNA have revealed no heterogeneity within the 2 genotypes. In the present study, a locus containing simple sequence repeats (microsatellites) was PCR amplified and sequenced from 94 C. parvum isolates, which were collected from humans (immunocompetent and immunocompromized individuals, outbreak and single cases) and from several animal hosts in 3 continents. The analysis revealed that genotype ‘H’ can be further differentiated into 2 subgenotypes, and genotype ‘C’ can be further differentiated into 4 subgenotypes. The 6 subgenotypes differ in terms of expansions/contractions of the microsatellite repeats and by point mutations. Some subgenotypes showed a wide geographical distribution, whereas others were restricted to specific regions. Therefore, microsatellites are informative markers for more defined studies on the epidemiology, the transmission routes, and the population structure of this parasite.

(Received July 29 1999)
(Revised October 4 1999)
(Accepted October 4 1999)


Key Words: Cryptosporidium parvum; microsatellites; genetic polymorphism; human genotypes; animal genotypes.

Correspondence:
c1 Corresponding author: Laboratory of Parasitology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy. Tel: +39 06 49 90 30 17. Fax: +39 06 49 38 70 65. E-mail: caccio@iss.it


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