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1.
Tanriverdi S Markovics A Arslan MO Itik A Shkap V Widmer G 《Applied and environmental microbiology》2006,72(4):2507-2513
Cryptosporidium parvum is an apicomplexan parasite that infects humans and ruminants. C. parvum isolated from cattle in northeastern Turkey and in Israel was genotyped using multiple polymorphic genetic markers, and the two populations were compared to assess the effect of cattle husbandry on the parasite's population structure. Dairy herds in Israel are permanently confined with essentially no opportunity for direct herd-to-herd transmission, whereas in Turkey there are more opportunities for transmission as animals range over wider areas and are frequently traded. A total of 76 C. parvum isolates from 16 locations in Israel and seven farms in the Kars region in northeastern Turkey were genotyped using 16 mini- and microsatellite markers. Significantly, in both countries distinct multilocus genotypes confined to individual farms were detected. The number of genotypes per farm was higher and mixed isolates were more frequent in Turkey than in Israel. As expected from the presence of distinct multilocus genotypes in individual herds, linkage disequilibrium among loci was detected in Israel. Together, these observations show that genetically distinct populations of C. parvum can emerge within a group of hosts in a relatively short time. This may explain the frequent detection of host-specific genotypes with unknown taxonomic status in surface water and the existence of geographically restricted C. hominis genotypes in humans. 相似文献
2.
Grant R. Herges Giovanni Widmer Mark E. Clark Eakalak Khan Catherine W. Giddings Matt Brewer John M. McEvoy 《Applied and environmental microbiology》2012,78(22):8096-8101
Cryptosporidium parvum is a zoonotic protozoan parasite that causes cryptosporidiosis, an infectious diarrheal disease primarily affecting humans and neonatal ruminants. Understanding the transmission dynamics of C. parvum, particularly the specific contributions of zoonotic and anthroponotic transmission, is critical to the control of this pathogen. This study used a population genetics approach to better understand the transmission of C. parvum in the Upper Midwest United States. A total of 254 C. parvum isolates from cases of human cryptosporidiosis in Minnesota and Wisconsin and diarrheic calves in Minnesota, Wisconsin, and North Dakota were genotyped at eight polymorphic loci. Isolates with a complete profile from all eight loci (n = 212) were used to derive a multilocus genotype (MLT), which was used in population genetic analyses. Among the 94 MLTs identified, 60 were represented by a single isolate. Approximately 20% of isolates belonged to MLT 2, a group that included both human and cattle isolates. Population analyses revealed a predominantly panmictic population with no apparent geographic or host substructuring. 相似文献
3.
Joaquín Quílez Claudia Vergara-Castiblanco Luis Monteagudo Emilio del Cacho Caridad Sánchez-Acedo 《Applied and environmental microbiology》2013,79(17):5363-5371
A stock of 148 Cryptosporidium parvum DNA extracts from lambs and goat kids selected from a previous study examining the occurrence of Cryptosporidium species and GP60 subtypes in diarrheic lambs and goat kids in northeastern Spain was further characterized by a multilocus fragment typing approach with six mini- and microsatellite loci. Various degrees of polymorphism were seen at all but the MS5 locus, although all markers exhibited two major alleles accounting for more than 75% of isolates. A total of 56 multilocus subtypes (MLTs) from lambs (48 MLTs) and goat kids (11 MLTs) were identified. Individual isolates with mixed MLTs were detected on more than 25% of the farms, but most MLTs (33) were distinctive for individual farms, revealing the endemicity of cryptosporidial infections on sheep and goat farms. Comparison with a previous study in calves in northern Spain using the same six-locus subtyping scheme showed the presence of host-associated alleles, differences in the identity of major alleles, and very little overlap in MLTs between C. parvum isolates from lambs and those from calves (1 MLT) or isolates from lambs and those from goat kids (3 MLTs). The Hunter-Gaston index of the multilocus technique was 0.976 (95% confidence interval [CI], 0.970 to 0.982), which supports its high discriminatory power for strain typing and epidemiological tracking. Population analyses revealed the presence of two host-associated subpopulations showing epidemic clonality among the C. parvum isolates infecting calves and lambs/goat kids, respectively, although evidence of genetic flow between the two subpopulations was also detected. 相似文献
4.
Genetic Diversity within Cryptosporidium parvum and Related Cryptosporidium Species 总被引:3,自引:0,他引:3
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Lihua Xiao Una M. Morgan Josef Limor Ananias Escalante Michael Arrowood William Shulaw R. C. A. Thompson Ronald Fayer Altaf A. Lal 《Applied microbiology》1999,65(8):3386-3391
To assess the genetic diversity in Cryptosporidium parvum, we have sequenced the small subunit (SSU) rRNA gene of seven Cryptosporidium spp., various isolates of C. parvum from eight hosts, and a Cryptosporidium isolate from a desert monitor. Phylogenetic analysis of the SSU rRNA sequences confirmed the multispecies nature of the genus Cryptosporidium, with at least four distinct species (C. parvum, C. baileyi, C. muris, and C. serpentis). Other species previously defined by biologic characteristics, including C. wrairi, C. meleagridis, and C. felis, and the desert monitor isolate, clustered together or within C. parvum. Extensive genetic diversities were present among C. parvum isolates from humans, calves, pigs, dogs, mice, ferrets, marsupials, and a monkey. In general, specific genotypes were associated with specific host species. A PCR-restriction fragment length polymorphism technique previously developed by us could differentiate most Cryptosporidium spp. and C. parvum genotypes, but sequence analysis of the PCR product was needed to differentiate C. wrairi and C. meleagridis from some of the C. parvum genotypes. These results indicate a need for revision in the taxonomy and assessment of the zoonotic potential of some animal C. parvum isolates. 相似文献
5.
Valentina Bianchini Laura Borella Valentina Benedetti Antonio Parisi Angela Miccolupo Eliana Santoro Camilla Recordati Mario Luini 《Applied and environmental microbiology》2014,80(6):1832-1837
Thermotolerant Campylobacter spp. are frequently the cause of human gastroenteritis and have assumed more importance in Italy following the increased consumption of raw milk. Our objectives were to determine the prevalence and genotypes of Campylobacter spp. in dairy herds and to investigate the possible sources of bulk milk contamination. Bulk milk from dairy herds (n = 282) was cultured for Campylobacter spp. and Enterobacteriaceae. At three Campylobacter jejuni-positive farms, bovine feces, pigeon intestines, milk, and water points were also investigated. Isolates were identified by PCR and genotyped using multilocus sequence typing (MLST). C. jejuni was detected in 34 (12%) bulk milk samples. The strains belonged to 14 sequence types, and the most common clonal complexes were CC-21, CC-48, and CC-403. No association was demonstrated between the presence of C. jejuni and high levels of Enterobacteriaceae in bulk milk. At the three farms examined, C. jejuni was isolated from bovine feces (25/82 [30.5%]), pigeon intestines (13/60 [21.7%]), bulk milk (10/24 [41.7%]), and water points (4/16 [25%]). MLST revealed lineages that were common between milk and bovine feces but distinct between cattle and pigeons. In one herd, C. jejuni with the same genotype was isolated repeatedly from bulk milk and a cow with an udder infection. Our results showed a high prevalence of C. jejuni in bulk milk and suggested that udder excretion, in addition to fecal matter, may be a route of bulk milk contamination. MLST analysis indicated that pigeons are probably not relevant for the transmission of C. jejuni to cattle and for milk contamination. 相似文献
6.
The intra-herd and intra-host genetic variability of 123 Cryptosporidium parvum isolates was investigated using a multilocus fragment typing approach with eleven variable-number tandem-repeat (VNTR) loci and the GP60 gene. Isolates were collected from intensively farmed diarrheic pre-weaned calves originating from 31 dairy farms in three adjoining regions in northern Spain (País Vasco, Cantabria and Asturias). The multilocus tool demonstrated an acceptable typeability, with 104/123 samples amplifying at all twelve loci. The ML2, TP14, GP60 and the previously un-described minisatellite at locus cgd2_3850 were the most discriminatory markers, while others may be dismissed as monomorphic (MSB) or less informative (CP47, ML1 and the novel minisatellites at loci Cgd1_3670 and Cgd6_3940). The 12-satellite typing tool provided a Hunter-Gaston index (HGDI) of 0.987 (95% CI, 0.982–0.992), and differentiated a total of 70 multilocus subtypes (MLTs). The inclusion of only the four most discriminatory markers dramatically reduced the number of MLTs (n: 44) but hardly reduced the HGDI value. A total of 54 MLTs were distinctive for individual farms, indicating that cryptosporidiosis is an endemic condition on most cattle farms. However, a high rate of mixed infections was detected, suggesting frequent meiotic recombination. Namely, multiple MLTs were seen in most farms where several specimens were analyzed (90.5%), with up to 9 MLTs being found on one farm, and individual specimens with mixed populations being reported on 11/29 farms. Bayesian Structure analysis showed that over 35% of isolates had mixed ancestry and analysis of evolutionary descent using the eBURST algorithm detected a high rate (21.4%) of MLTs appearing as singletons, indicating a high degree of genetic divergence. Linkage analysis found evidence of linkage equilibrium and an overall panmictic structure within the C. parvum population in this discrete geographical area. 相似文献
7.
Genotyping Cryptosporidium parvum with an hsp70 Single-Nucleotide Polymorphism Microarray 总被引:1,自引:0,他引:1
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Timothy M. Straub Don S. Daly Sharon Wunshel Paul A. Rochelle Ricardo DeLeon Darrell P. Chandler 《Applied microbiology》2002,68(4):1817-1826
We investigated the application of an oligonucleotide microarray to (i) specifically detect Cryptosporidium spp., (ii) differentiate between closely related C. parvum isolates and Cryptosporidium species, and (iii) differentiate between principle genotypes known to infect humans. A microarray of 68 capture probes targeting seven single-nucleotide polymorphisms (SNPs) within a 190-bp region of the hsp70 gene of Cryptosporidium parvum was constructed. Labeled hsp70 targets were generated by PCR with biotin- or Cy3-labeled primers. Hybridization conditions were optimized for hybridization time, temperature, and salt concentration. Two genotype I C. parvum isolates (TU502 and UG502), two C. parvum genotype II isolates (Iowa and GCH1), and DNAs from 22 non-Cryptosporidium sp. organisms were used to test method specificity. Only DNAs from C. parvum isolates produced labeled amplicons that could be hybridized to and detected on the array. Hybridization patterns between genotypes were visually distinct, but identification of SNPs required statistical analysis of the signal intensity data. The results indicated that correct mismatch discrimination could be achieved for all seven SNPs for the UG502 isolate, five of seven SNPs for the TU502 isolate, and six of seven SNPs for both the Iowa and GCH1 isolates. Even without perfect mismatch discrimination, the microarray method unambiguously distinguished between genotype I and genotype II isolates and demonstrated the potential to differentiate between other isolates and species on a single microarray. This method may provide a powerful new tool for water utilities and public health officials for assessing point and nonpoint source contamination of water supplies. 相似文献
8.
Sequence Polymorphism in the β-Tubulin Gene Reveals Heterogeneous and Variable Population Structures in Cryptosporidium parvum
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Giovanni Widmer Laurie Tchack Cynthia L. Chappell Saul Tzipori 《Applied microbiology》1998,64(11):4477-4481
Restriction fragment length polymorphism (RFLP) analysis of isolates of Cryptosporidium parvum has revealed two subgroups, termed H and C. The limited resolution of the RFLP method precludes an in-depth study of the genetic structure of C. parvum populations. Published C. parvum restriction polymorphisms lie within protein-coding regions known to be more homogeneous than noncoding sequences. To better assess the degrees of heterogeneity between and within C. parvum isolates, sequence polymorphism in the β-tubulin intron, the only C. parvum intron described to date, was investigated. In contrast to the two genotypes distinguished by multilocus RFLP, several alleles were detected by sequence and RFLP analysis of the β-tubulin intron and adjacent exon 2. Isolates carrying different β-tubulin alleles were found. Significantly, one of the β-tubulin alleles present in two geographically unrelated isolates combined features of C- and H-type isolates, suggesting that it might have arisen from a recombination event. A comparison of multiple samples of a calf-propagated laboratory isolate showed that the ratio of different β-tubulin alleles fluctuated during serial passage. 相似文献
9.
Drumo R Widmer G Morrison LJ Tait A Grelloni V D'Avino N Pozio E Cacciò SM 《Applied and environmental microbiology》2012,78(10):3523-3529
Recent studies have revealed extensive genetic variation among isolates of Cryptosporidium parvum, an Apicomplexan parasite that causes gastroenteritis in both humans and animals worldwide. The parasite's population structure is influenced by the intensity of transmission, the host-parasite interaction, and husbandry practices. As a result, C. parvum populations can be panmictic, clonal, or even epidemic on both a local scale and a larger geographical scale. To extend the study of C. parvum populations to an unexplored region, 173 isolates of C. parvum collected in Italy from humans and livestock (calf, sheep, and goat) over a 10-year period were genotyped using a multilocus scheme based on 7 mini- and microsatellite loci. In agreement with other studies, extensive polymorphism was observed, with 102 distinct multilocus genotypes (MLGs) identified among 173 isolates. The presence of linkage disequilibrium, the confinement of MLGs to individual farms, and the relationship of many MLGs inferred using network analysis (eBURST) suggest a predominantly clonal population structure, but there is also evidence that part of the diversity can be explained by genetic exchange. MLGs from goats were found to differ from bovine and sheep MLGs, supporting the existence of C. parvum subpopulations. Finally, MLGs from isolates collected between 1997 and 1999 were also identified as a distinct subgroup in principal-component analysis and eBURST analysis, suggesting a continuous introduction of novel genotypes in the parasite population. 相似文献
10.
Prevalence and Antimicrobial Resistance of Thermophilic Campylobacter spp. from Cattle Farms in Washington State
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Wonki Bae Katherine N. Kaya Dale D. Hancock Douglas R. Call Yong Ho Park Thomas E. Besser 《Applied microbiology》2005,71(1):169-174
The prevalence of thermophilic Campylobacter spp. was investigated in cattle on Washington State farms. A total of 350 thermophilic Campylobacter isolates were isolated from 686 cattle sampled on 15 farms (eight dairies, two calf rearer farms, two feedlots, and three beef cow-calf ranches). Isolate species were identified with a combination of phenotypic tests, hipO colony blot hybridization, and multiplex lpxA PCR. Breakpoint resistance to four antimicrobials (ciprofloxacin, nalidixic acid, erythromycin, and doxycycline) was determined by agar dilution. Campylobacter jejuni was the most frequent species isolated (34.1%), followed by Campylobacter coli (7.7%) and other thermophilic campylobacters (1.5%). The most frequently detected resistance was to doxycycline (42.3% of 350 isolates). Isolates from calf rearer facilities were more frequently doxycycline resistant than isolates from other farm types. C. jejuni was most frequently susceptible to all four of the antimicrobial drugs studied (58.8% of 272 isolates). C. coli isolates were more frequently resistant than C. jejuni, including resistance to quinolone antimicrobials (89.3% of isolates obtained from calves on calf rearer farms) and to erythromycin (72.2% of isolates obtained from feedlot cattle). Multiple drug resistance was more frequent in C. coli (51.5%) than in C. jejuni (5.1%). The results of this study demonstrate that C. jejuni is widely distributed among Washington cattle farms, while C. coli is more narrowly distributed but significantly more resistant. 相似文献
11.
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.The lack of variable morphological traits to identify oocysts from different Cryptosporidium species has driven the development of numerous genotyping methods to survey the diversity in this genus. Genetic markers such as single-nucleotide polymorphisms (24), restriction fragment length polymorphisms (7, 34), random amplification methods (17, 20), conformational polymorphisms (11), simple sequence repeats (3, 10), and DNA sequence polymorphisms (6, 36) have been used to type Cryptosporidium oocysts excreted by humans and animals and oocysts recovered from the environment. This effort has led to a deeper understanding of the taxonomy of the genus Cryptosporidium and the epidemiology of cryptosporidiosis in humans and livestock. As a result of this work, two species responsible for a majority of human infections, Cryptosporidium parvum and C. hominis, were identified (21) and our understanding of the taxonomy of the genus was refined (35).The application of genetic markers to define species, i.e., reproductively isolated populations, is straightforward. At this taxonomic level, all genotypes cosegregate and the choice of marker will have little impact on the outcome, provided that the marker, or combination thereof, is sufficiently polymorphic. The classical example is the variable region of the small-subunit rRNA gene which has been used, as in other taxa, to define many Cryptosporidium species. For studying intraspecies polymorphism, the choice of genotyping methods needs to take into consideration the potential for genetic recombination. This is clearly the case for species such as those belonging to the genus Cryptosporidium, which are known to undergo an obligatory sexual cycle during which genetically dissimilar haplotypes can recombine (28).Among the many markers that have been applied in epidemiological surveys of C. parvum and C. hominis, a variable fragment of the gene encoding a sporozoite surface glycoprotein (8, 26) has been particularly popular. As a result of the widespread adoption of this marker, variously named GP60, cpgp40/15, or gp40, numerous alleles have been identified and deposited in GenBank. The analysis of this continuously growing collection of GP60 sequences has led to the identification of groups of related sequences (18, 27, 32, 33). In an attempt to simplify the comparison of GP60 genotypes among different laboratories, a GP60 nomenclature distinguishing the main groups of alleles has been created (26) and later refined (27).The desire to streamline the genotyping of large numbers of Cryptosporidium isolates collected during surveys has led to the widespread adoption of the GP60 genotype as the only marker for defining intraspecies groups. Since this approach is not compatible with the reassortment of unlinked loci, the classification of isolates on the basis of the GP60 genotype, or any other single marker, needs to be evaluated. Within a recombining population, no single genetic marker can a priori be expected to serve as a surrogate for other loci or multilocus genotypes (MLGs), and any apparent clustering of isolates is dependent on the marker. To investigate the validity of the GP60 genotyping method as commonly applied to the classification of C. parvum and C. hominis isolates, the GP60 genotype was added to a previously described 9-locus genotype (29) and a diversified collection of 10-locus genotypes was examined for intraspecies clusters. We show that, with the exception of some GP60 alleles apparently restricted to human C. parvum, neither C. parvum nor C. hominis GP60 alleles define subspecies genotypes. These results are discussed in the context of ongoing research to better understand the population structure of these parasites and identify genotypes associated with virulence traits. 相似文献
12.
Phylogenetic Relationships of Cryptosporidium Parasites Based on the 70-Kilodalton Heat Shock Protein (HSP70) Gene 总被引:1,自引:0,他引:1
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Irshad M. Sulaiman Una M. Morgan R. C. Andrew Thompson Altaf A. Lal Lihua Xiao 《Applied microbiology》2000,66(6):2385-2391
We have characterized the nucleotide sequences of the 70-kDa heat shock protein (HSP70) genes of Cryptosporidium baileyi, C. felis, C. meleagridis, C. muris, C. serpentis, C. wrairi, and C. parvum from various animals. Results of the phylogenetic analysis revealed the presence of several genetically distinct species in the genus Cryptosporidium and eight distinct genotypes within the species C. parvum. Some of the latter may represent cryptic species. The phylogenetic tree constructed from these sequences is in agreement with our previous results based on the small-subunit rRNA genes of Cryptosporidium parasites. The Cryptosporidium species formed two major clades: isolates of C. muris and C. serpentis formed the first major group, while isolates of C. felis, C. meleagridis, C. wrairi, and eight genotypes of C. parvum formed the second major group. Sequence variations were also observed between C. muris isolates from ruminants and rodents. The HSP70 gene provides another useful locus for phylogenetic analysis of the genus Cryptosporidium. 相似文献
13.
Use of Multilocus Sequence Typing To Investigate the Association between the Presence of Campylobacter spp. in Broiler Drinking Water and Campylobacter Colonization in Broilers
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I. D. Ogden M. MacRae M. Johnston N. J. C. Strachan A. J. Cody K. E. Dingle D. G. Newell 《Applied microbiology》2007,73(16):5125-5129
The presence of campylobacters in broiler chickens and throughout the broiler water delivery systems of 12 farms in northeastern Scotland was investigated by sensitive enrichment methods and large-volume filtration. Campylobacter presence was independent of the water source and whether the water was treated. The genotypes of Campylobacter jejuni isolates recovered from chickens and various locations within the water delivery systems were compared by multilocus sequence typing. Matching strains in shed header tanks and birds were found at 1 of the 12 farms investigated. However, the sequence of contamination or whether the source was within or outside the shed was not determined. Nevertheless, these data provide evidence that drinking water could be associated with broiler infection by campylobacters. 相似文献
14.
Molecular Characterization of Giardia Isolates from Calves and Humans in a Region in Which Dairy Farming Has Recently Intensified
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Cynthia L. Winkworth James J. Learmonth Christoph D. Matthaei Colin R. Townsend 《Applied microbiology》2008,74(16):5100-5105
Giardiasis is a notifiable disease of high prevalence in New Zealand, but there is limited knowledge about the sources of Giardia duodenalis genotypes that can potentially cause human infections. Dairy calves are one environmental source of Giardia isolates, but it is unknown whether they harbor genotypes that are potentially capable of causing infections in humans. To address these questions, 40 Giardia isolates from calves and 30 from humans, living in the same region and collected over a similar period, were genotyped using the β-giardin gene. The G. duodenalis genetic assemblages A and B were identified from both calves and humans, and genotype comparisons revealed a substantial overlap of identical genotypes from the two hosts for both assemblages. Significantly, no assemblage E (the genotype commonly found in cattle elsewhere in the world) has been detected in New Zealand livestock to date. Given recent and rapid land use conversions to dairy farming in many South Island regions of New Zealand, an increasingly large concentration of domestic cattle harboring genotypes potentially capable of causing infections in humans is particularly concerning. 相似文献
15.
Tatsunori Masatani Ragab M. Fereig Konosuke Otomaru Shingo Ishikawa Isshu Kojima Seiji Hobo Yoshifumi Nishikawa 《Parasitology international》2018,67(6):763-767
Cryptosporidium parvum and Neospora caninum are common parasites in domesticated cattle worldwide, including in Japan. We carried out a serological survey to detect C. parvum and N. caninum infection among cattle in the southern Kyushu region of Japan—including the small islands—by indirect enzyme-linked immunosorbent assay based on recombinant antigens. We found that total seropositivity in 570 Japanese black cattle was 96.3% for C. parvum and 18.4% for N. caninum. Although seroprevalence was correlated with cattle age, differences in the seroprevalence of C. parvum among age groups were not statistically significant. On the other hand, N. caninum seroprevalence increased with age, suggesting horizontal transmission through ingestion of food or water contaminated with oocysts. These findings underscore the importance of monitoring C. parvum and N. caninum in cattle and implementing measures to prevent the spread of infection to other livestock and to humans. 相似文献
16.
Inferences about the Global Population Structures of Cryptosporidium parvum and Cryptosporidium hominis
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Sultan Tanrverdi Alex Grinberg Rachel M. Chalmers Paul R. Hunter Zorana Petrovic Donna E. Akiyoshi Eric London Linghui Zhang Saul Tzipori James K. Tumwine Giovanni Widmer 《Applied microbiology》2008,74(23):7227-7234
Cryptosporidium parvum and Cryptosporidium hominis are two related species of apicomplexan protozoa responsible for the majority of human cases of cryptosporidiosis. In spite of their considerable public health impact, little is known about the population structures of these species. In this study, a battery of C. parvum and C. hominis isolates from seven countries was genotyped using a nine-locus DNA subtyping scheme. To assess the existence of geographical partitions, the multilocus genotype data were mined using a cluster analysis based on the nearest-neighbor principle. Within each country, the population genetic structures were explored by combining diversity statistical tests, linkage disequilibrium, and eBURST analysis. For both parasite species, a quasi-complete phylogenetic segregation was observed among the countries. Cluster analysis accurately identified recently introduced isolates. Rather than conforming to a strict paradigm of either a clonal or a panmictic population structure, data are consistent with a flexible reproductive strategy characterized by the cooccurrence of both propagation patterns. The relative contribution of each pattern appears to vary between the regions, perhaps dependent on the prevailing ecological determinants of transmission. 相似文献
17.
Phylogenetic Analysis of Cryptosporidium Parasites Based on the Small-Subunit rRNA Gene Locus 总被引:8,自引:0,他引:8
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Lihua Xiao Lillian Escalante Chunfu Yang Irshad Sulaiman Anannias A. Escalante Richard J. Montali Ronald Fayer Altaf A. Lal 《Applied microbiology》1999,65(4):1578-1583
Biological data support the hypothesis that there are multiple species in the genus Cryptosporidium, but a recent analysis of the available genetic data suggested that there is insufficient evidence for species differentiation. In order to resolve the controversy in the taxonomy of this parasite genus, we characterized the small-subunit rRNA genes of Cryptosporidium parvum, Cryptosporidium baileyi, Cryptosporidium muris, and Cryptosporidium serpentis and performed a phylogenetic analysis of the genus Cryptosporidium. Our study revealed that the genus Cryptosporidium contains the phylogenetically distinct species C. parvum, C. muris, C. baileyi, and C. serpentis, which is consistent with the biological characteristics and host specificity data. The Cryptosporidium species formed two clades, with C. parvum and C. baileyi belonging to one clade and C. muris and C. serpentis belonging to the other clade. Within C. parvum, human genotype isolates and guinea pig isolates (known as Cryptosporidium wrairi) each differed from bovine genotype isolates by the nucleotide sequence in four regions. A C. muris isolate from cattle was also different from parasites isolated from a rock hyrax and a Bactrian camel. Minor differences were also detected between C. serpentis isolates from snakes and lizards. Based on the genetic information, a species- and strain-specific PCR-restriction fragment length polymorphism diagnostic tool was developed. 相似文献
18.
Guang-Hui Zhao Wan-Xin Ren Man Gao Qing-Qing Bian Bing Hu Mei-Mei Cong Qing Lin Rong-Jun Wang Meng Qi Mao-Zhen Qi Xing-Quan Zhu Long-Xian Zhang 《PloS one》2013,8(4)
The present study examined the prevalence and genotypes of Cryptosporidium andersoni in cattle in Shaanxi province, China. A total of 2071 fecal samples (847 from Qinchuan cattle and 1224 from dairy cattle) were examined for the presence of Cryptosporidium oocysts, and 70 samples (3.4%) were C. andersoni-positive and those positive samples were identified by PCR amplification of the small subunit ribosomal RNA (SSU rRNA) and the Cryptosporidium oocyst wall protein (COWP) genes. C. andersoni was the only species found in the examined cattle in this province. Fifty-seven C. andersoni isolates were characterized into 5 MLST subtypes using multilocus sequence typing analysis, including a new subtype in the native beef breed Qinchuan cattle. All of these C. andersoni isolates presented a clonal genetic structure. These findings provide new insights into the genetic structure of C. andersoni isolates in Shaanxi province and basic data of Cryptosporidium prevalence status, which in turn have implications for controlling cryptosporidiosis in this province. 相似文献
19.
Greater Diversity of Shiga Toxin-Encoding Bacteriophage Insertion Sites among Escherichia coli O157:H7 Isolates from Cattle than in Those from Humans
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Thomas E. Besser Nurmohammad Shaikh Nicholas J. Holt Phillip I. Tarr Michael E. Konkel Preeti Malik-Kale Coilin W. Walsh Thomas S. Whittam James L. Bono 《Applied microbiology》2007,73(3):671-679
Escherichia coli O157:H7, a zoonotic human pathogen for which domestic cattle are a reservoir host, produces a Shiga toxin(s) (Stx) encoded by bacteriophages. Chromosomal insertion sites of these bacteriophages define three principal genotypes (clusters 1 to 3) among clinical isolates of E. coli O157:H7. Stx-encoding bacteriophage insertion site genotypes of 282 clinical and 80 bovine isolates were evaluated. A total of 268 (95.0%) of the clinical isolates, but only 41 (51.3%) of the bovine isolates, belonged to cluster 1, 2, or 3 (P < 0.001). Thirteen additional genotypes were identified in isolates from both cattle and humans (four genotypes), from only cattle (seven genotypes), or from only humans (two genotypes). Two other markers previously associated with isolates from cattle or with clinical isolates showed similar associations with genotype groups within bovine isolates; the tir allele sp-1 and the Q933W allele were under- and overrepresented, respectively, among cluster 1 to 3 genotypes. Stx-encoding bacteriophage insertion site typing demonstrated that there is broad genetic diversity of E. coli O157:H7 in the bovine reservoir and that numerous genotypes are significantly underrepresented among clinical isolates, consistent with the possibility that there is reduced virulence or transmissibility to humans of some bovine E. coli O157:H7 genotypes. 相似文献
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Maria das Graas C. Pereira Edward R. Atwill Melissa R. Crawford Rance B. Lefebvre 《Applied microbiology》1998,64(4):1584-1586
We evaluated whether nucleic acid amplification with primers specific for Cryptosporidium parvum followed by automated DNA sequence analysis of the PCR amplicons could differentiate between California isolates of C. parvum obtained from livestock, humans, and feral pigs. Almost complete sequence identity existed among the livestock isolates and between the livestock and human isolates. DNA sequences from feral pig isolates differed from those from livestock and humans by 1.0 to 1.2%. The reference sequence obtained by Laxer et al. (M. A. Laxer, B. K. Timblin, and R. J. Patel, Am. J. Trop. Med. Hyg. 45:688–694, 1991.) differed from California isolates of C. parvum by 1.8 to 3.2%. These data suggest that DNA sequence analysis of the amplicon of Laxer et al. does not allow for differentiation between various strains of C. parvum or that our collection of isolates obtained from various hosts from across California was limited to one strain of C. parvum. 相似文献