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Comparison of single- and multilocus genetic diversity in the protozoan parasites Cryptosporidium parvum and C. hominis.

ABSTRACT: The genotyping of numerous isolates of Cryptosporidium parasites has led to the definition of new species and a better understanding of the epidemiology of cryptosporidiosis. A single-locus genotyping method based on the partial sequence of a polymorphic sporozoite surface glycoprotein gene (GP60) has been favored by many for surveying Cryptosporidium parvum and C. hominis populations. Since genetically distinct Cryptosporidium parasites recombine in nature, it is unclear whether single-locus classifications can adequately represent intraspecies diversity. To address this question, we investigated whether multilocus genotypes of C. parvum and C. hominis cluster according to the GP60 genotype. C. hominis multilocus genotypes did not segregate according to this marker, indicating that for this species the GP60 sequence is not a valid surrogate for multilocus typing methods. In contrast, in C. parvum the previously described "anthroponotic" genotype was confirmed as a genetically distinct subspecies cluster characterized by a diagnostic GP60 allele. However, as in C. hominis, several C. parvum GP60 alleles did not correlate with distinct subpopulations. Given the rarity of some C. parvum GP60 alleles in our sample, the existence of additional C. parvum subgroups with unique GP60 alleles cannot be ruled out. We conclude that with the exception of genotypically distinct C. parvum subgroups, multilocus genotyping methods are needed to characterize C. parvum and C. hominis populations. Unless parasite virulence is controlled at the GP60 locus, attempts to find associations within species or subspecies between GP60 and phenotype are unlikely to be successful.

SUBMITTER: Widmer G

PROVIDER: S-EPMC2950454 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

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Comparison of single- and multilocus genetic diversity in the protozoan parasites Cryptosporidium parvum and C. hominis.

Widmer Giovanni G Lee Yongsun Y

Applied and environmental microbiology 20100813 19

The genotyping of numerous isolates of Cryptosporidium parasites has led to the definition of new species and a better understanding of the epidemiology of cryptosporidiosis. A single-locus genotyping method based on the partial sequence of a polymorphic sporozoite surface glycoprotein gene (GP60) has been favored by many for surveying Cryptosporidium parvum and C. hominis populations. Since genetically distinct Cryptosporidium parasites recombine in nature, it is unclear whether single-locus cl ...[more]

PMID: 20709840

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Project description:BACKGROUND:Non-human primates are often infected with human-pathogenic Cryptosporidium hominis subtypes, but rarely with Cryptosporidium parvum. In this study, 1452 fecal specimens were collected from farmed crab-eating macaques (Macaca fascicularis) in Hainan, China during the period April 2016 to January 2018. These specimens were analyzed for Cryptosporidium species and subtypes by using PCR and sequence analysis of the 18S rRNA and 60 kDa glycoprotein (gp60) genes, respectively. RESULTS:Altogether, Cryptosporidium was detected using 18S rRNA-based PCR in 132 (9.1%) sampled animals, with significantly higher prevalence in females (12.5% or 75/599 versus 6.1% or 43/706), younger animals (10.7% or 118/1102 in monkeys 1-3-years-old versus 4.0% or 14/350 in those over 3-years-old) and animals with diarrhea (12.6% or 46/365 versus 7.9% or 86/1087). Four Cryptosporidium species were identified, namely C. hominis, C. parvum, Cryptosporidium muris and Cryptosporidium ubiquitum in 86, 30, 15 and 1 animal, respectively. The identified C. parvum, C. hominis and C. ubiquitum were further subtyped by using gp60 PCR. Among them, C. parvum belonged to subtypes in two known subtype families, namely IIoA14G1 (in 18 animals) and IIdA19G1 (in 2 animals). In contrast, C. hominis mostly belonged to two new subtype families Im and In, which are genetically related to Ia and Id, respectively. The C. hominis subtypes identified included ImA18 (in 38 animals), InA14 (in six animals), InA26 (in six animals), InA17 (in one animal) and IiA17 (in three animals). The C. ubiquitum isolates belonged to subtype family XIId. By subtype, ImA18 and IIoA14G1 were detected in animals with diarrhea whereas the remaining ones were mostly found in asymptomatic animals. Compared with C. parvum and C. muris, higher oocyst shedding intensity was observed in animals infected with C. hominis, especially those infected with the Im subtype family. CONCLUSIONS:Data from the study suggest that crab-eating macaques are infected with diverse C. parvum and C. hominis subtypes. The C. parvum IIo subtype family previously seen in rodents in China has apparently expanded its host range.

Project description:Cryptosporidiosis and giardiasis are recognized as significant enteric diseases due to their long-term health effects in humans and their economic impact in agriculture and medical care. Molecular analysis is essential to identify species and genotypes causing these infectious diseases and provides a potential tool for monitoring. This study uses information on species and genetic variants to gain insights into the geographical distribution and spatial patterns of Cryptosporidium and Giardia parasites. Here, we describe the population heterogeneity of genotypic groups within Cryptosporidium and Giardia present in New Zealand using gp60 and gdh markers to compare the observed variation with other countries around the globe. Four species of Cryptosporidium (C. hominis, C. parvum, C. cuniculus and C. erinacei) and one species of Giardia (G. intestinalis) were identified. These species have been reported worldwide and there are not unique Cryptosporidium gp60 subtype families and Giardia gdh assemblages in New Zealand, most likely due to high gene flow of historical and current human activity (travel and trade) and persistence of large host population sizes. The global analysis revealed that genetic variants of these pathogens are widely distributed. However, genetic variation is underestimated by data biases (e.g. neglected submission of sequences to genetic databases) and low sampling. New genotypes are likely to be discovered as sampling efforts increase according to accumulation prediction analyses, especially for C. parvum. Our study highlights the need for greater sampling and archiving of genotypes globally to allow comparative analyses that help understand the population dynamics of these protozoan parasites. Overall our study represents a comprehensive overview for exploring local and global protozoan genotype diversity and advances our understanding of the importance for surveillance and potential risk associated with these infectious diseases.

Project description:BackgroundCryptosporidium hominis is a dominant species for human cryptosporidiosis. Within the species, IbA10G2 is the most virulent subtype responsible for all C. hominis-associated outbreaks in Europe and Australia, and is a dominant outbreak subtype in the United States. In recent yearsIaA28R4 is becoming a major new subtype in the United States. In this study, we sequenced the genomes of two field specimens from each of the two subtypes and conducted a comparative genomic analysis of the obtained sequences with those from the only fully sequenced Cryptosporidium parvum genome.ResultsAltogether, 8.59-9.05 Mb of Cryptosporidium sequences in 45-767 assembled contigs were obtained from the four specimens, representing 94.36-99.47% coverage of the expected genome. These genomes had complete synteny in gene organization and 96.86-97.0% and 99.72-99.83% nucleotide sequence similarities to the published genomes of C. parvum and C. hominis, respectively. Several major insertions and deletions were seen between C. hominis and C. parvum genomes, involving mostly members of multicopy gene families near telomeres. The four C. hominis genomes were highly similar to each other and divergent from the reference IaA25R3 genome in some highly polymorphic regions. Major sequence differences among the four specimens sequenced in this study were in the 5' and 3' ends of chromosome 6 and the gp60 region, largely the result of genetic recombination.ConclusionsThe sequence similarity among specimens of the two dominant outbreak subtypes and genetic recombination in chromosome 6, especially around the putative virulence determinant gp60 region, suggest that genetic recombination plays a potential role in the emergence of hyper-transmissible C. hominis subtypes. The high sequence conservation between C. parvum and C. hominis genomes and significant differences in copy numbers of MEDLE family secreted proteins and insulinase-like proteases indicate that telomeric gene duplications could potentially contribute to host expansion in C. parvum.

Dataset Information

Comparison of single- and multilocus genetic diversity in the protozoan parasites Cryptosporidium parvum and C. hominis.

Publications

Comparison of single- and multilocus genetic diversity in the protozoan parasites Cryptosporidium parvum and C. hominis.

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