Differential evolution of repetitive sequences in Cryptosporidium parvum and Cryptosporidium hominis

• Published in: Infection, genetics and evolution Vol. 6; no. 2; pp. 113 - 122
• Main Authors: Tanrıverdi, Sultan, Widmer, Giovanni
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2006
• Subjects: Alleles; Amino Acid Sequence; Animals; Base Sequence; Cryptosporidium - genetics; Cryptosporidium - isolation & purification; Cryptosporidium hominis; Cryptosporidium parvum; Cryptosporidium parvum - genetics; Cryptosporidium parvum - isolation & purification; DNA, Protozoan - analysis; DNA, Protozoan - genetics; Electrophoresis; Evolution, Molecular; Gene Frequency; Genetic Markers; Genetic polymorphism; Length polymorphism; Microsatellite; Microsatellite Repeats; Minisatellite; Molecular Sequence Data; Oocysts - genetics; Oocysts - isolation & purification; Open Reading Frames; Phylogeny; Polymorphism, Genetic; Polymorphism, Restriction Fragment Length; Repetitive Sequences, Nucleic Acid - genetics; Sequence Analysis, DNA; Sequence Deletion; Species Specificity; Cryptosporidium hominis; Microsatellite; Cryptosporidium parvum; Length polymorphism; Minisatellite; Genetic polymorphism
• ISSN: 1567-1348; 1567-7257
• DOI: 10.1016/j.meegid.2005.02.002

Cryptosporidium parvum and Cryptosporidium hominis are two morphologically identical species of Apicomplexan protozoa infecting humans. Although the genomes of these species are 97% identical, their host range is strikingly different. C. parvum infects humans and animals and is primarily a zoonotic infection, whereas C. hominis is typically not detected in animals. The extent of genetic polymorphism in both species has been surveyed locally, but not on a larger geographical scale. Herein, a collection of unrelated C. parvum and C. hominis isolates was genotyped using multiple, randomly distributed micro- and minisatellites. In average, minisatellites, consisting of tandemly repeated sequence motifs of 6–24 basepair, were more polymorphic than microsatellites. When the average number of micro- and minisatellite alleles per locus was used as a measure of heterogeneity, no difference between C. parvum and C. hominis was found. However, the frequency distribution of alleles in both species was significantly different and in 6 of the 14 loci the size of the C. parvum and C. hominis repeats did not overlap. Assuming that C. parvum and C. hominis evolved from a common ancestor, these observations suggest a differential evolution of repeat length at these loci.