@article {782,
	title = {Experimental evidence for genetic recombination in the opportunistic pathogen Cryptosporidium parvum.},
	journal = {Mol Biochem Parasitol},
	volume = {119},
	year = {2002},
	month = {2002 Jan},
	pages = {55-62},
	abstract = {Cryptosporidium parvum is an intracellular protozoan parasite causing intestinal malabsorption and diarrhea in humans. The infection is usually self-limiting, although persistent cryptosporidosis is observed in immunocompromised and malnourished individuals. As with other Apicomplexa, the life cycle of Cryptosporidium is thought to comprise a sexual phase, during which a motile microgamont fuses with a sessile macrogamont. The four sporozoites found within each oocyst (the infectious form excreted in the feces) are thought to be the product of a meiotic division taking place immediately following fertilization, but the existence of a meiotic cycle in this genus has not been tested experimentally. To substantiate the occurrence of meiotic recombination in this species, we performed a genetic cross between two distinct isolates of C. parvum co-infected in INF-gamma knockout mice. We found that mixed infections produced recombinant progeny characterized by multilocus genotypes comprising alleles inherited from each parental line. This observation represents the first demonstration of sexual recombination in this pathogen. Together with the occurrence of genetically heterogeneous infections, this finding suggests that outcrossing between genotypes may occur in nature. Experimental crosses among Cryptosporidium populations will facilitate mapping of clinically relevant genes, the delineation of Cryptosporidium species, and defining the taxonomical status of C. parvum subtypes and host-specific genotypes.},
	keywords = {Animals, Conserved Sequence, Crosses, Genetic, Cryptosporidiosis, Cryptosporidium parvum, Deer, Female, Genotype, Humans, Male, Mice, Mice, Knockout, Microsatellite Repeats, Opportunistic Infections, Polymerase Chain Reaction, Recombination, Genetic, Survival Rate},
	issn = {0166-6851},
	author = {Feng, Xiaochuan and Rich, Stephen M and Tzipori, Saul and Widmer, Giovanni}
}
@article {787,
	title = {Extensive polymorphism in Cryptosporidium parvum identified by multilocus microsatellite analysis.},
	journal = {Appl Environ Microbiol},
	volume = {66},
	year = {2000},
	month = {2000 Aug},
	pages = {3344-9},
	abstract = {Restriction fragment length polymorphism and DNA sequence analysis discern two main types of Cryptosporidium parvum. We present a survey of length polymorphism at several microsatellite loci for type 1 and type 2 isolates. A total of 14 microsatellite loci were identified from C. parvum DNA sequences deposited in public databases. All repeats were mono-, di-, and trinucleotide repeats of A, AT, and AAT, reflecting the high AT content of the C. parvum genome. Several of these loci showed significant length polymorphism, with as many as seven alleles identified for a single locus. Differences between alleles ranged from 1 to 27 bp. Karyotype analysis using probes flanking three microsatellites localized each marker to an individual chromosomal band, suggesting that these markers are single copy. In a sample of 19 isolates for which at least three microsatellites were typed, a majority of isolates displayed a unique multilocus fingerprint. Microsatellite analysis of isolates passaged between different host species identified genotypic changes consistent with changes in parasite populations.},
	keywords = {Animals, Base Sequence, Cattle, Cryptosporidiosis, Cryptosporidium parvum, DNA, Protozoan, Humans, Karyotyping, Mice, Mice, Knockout, Microsatellite Repeats, Molecular Sequence Data, Polymerase Chain Reaction, Polymorphism, Genetic, Sequence Analysis, DNA},
	issn = {0099-2240},
	author = {Feng, X and Rich, S M and Akiyoshi, D and Tumwine, J K and Kekitiinwa, A and Nabukeera, N and Tzipori, S and Widmer, G}
}
