title: Population structure of natural and propagated isolates of Cryptosporidium parvum, C. hominis and C. meleagridis.
abstract: The three protozoan species Cryptosporidium parvum, C. meleagridis and C. hominis (phylum Apicomplexa) are enteric pathogens of humans. The former two species are zoonotic and the latter is thought to infect only humans. To better characterize the structure and transmission of natural and laboratory-propagated isolates, we analyzed a collection of archived human and animal isolates of these three species by deep-sequencing polymerase chain reaction products amplified from a polymorphic sequence on chromosome 1. Thousands of screened 200-nucleotide sequences were analyzed to compare the diversity among samples, to assess the impact of laboratory propagation on population complexity and to identify taxonomically mixed isolates. Contrary to our expectation, repeated propagation in animals did not reduce intra-isolate diversity nor was diversity associated with host species. Significantly, in most samples, sequences characteristic of a different species were identified. The presence of C. hominis alleles in C. parvum and C. meleagridis isolates confirms earlier reports of mixed isolates and raises the possibility that the host range of C. hominis is broader than typically assumed. In a genetically divergent isolate of C. parvum, a majority of sequences was found to be recombinant, suggesting that this genotype originated from a C. parvum × C. hominis recombination event.
authors.affiliation: Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, MA, USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Widmer
authors.forename: Refaat
authors.initials: R
authors.lastname: Ras
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Chalmers
authors.forename: Kristin
authors.initials: K
authors.lastname: Elwin
authors.forename: Enas
authors.initials: E
authors.lastname: Desoky
authors.forename: Ahmed
authors.initials: A
authors.lastname: Badawy
mesh_terms: D000818:Animals; D001483:Base Sequence; D003457:Cryptosporidiosis / Q000469:parasitology / Q000635:transmission*; D016785:Cryptosporidium parvum / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D016054:DNA, Protozoan / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D058507:Host Specificity / Q000235:genetics; D006801:Humans; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D012337:RNA, Ribosomal, 18S