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Genotyping of Giardia duodenalis cysts by new real-time PCR assays for detection of mixed infections in human samples

dc.contributor.authorAlmeida, André
dc.contributor.authorPozio, Edoardo
dc.contributor.authorCacciò, Simone M.
dc.date.accessioned2011-09-19T12:33:10Z
dc.date.available2011-09-19T12:33:10Z
dc.date.issued2010-03
dc.description.abstractOf the seven genetic groups, or assemblages, currently recognized in the Giardia duodenalis species complex, only assemblages A and B are associated with human infection, but they also infect other mammals. Recent investigations have suggested the occurrence of genetic exchanges among isolates of G. duodenalis, and the application of assemblage-specific PCR has shown both assemblages A and B in a significant number of human infections. In this work, three real-time quantitative (qPCR) assays were developed to target the G. duodenalis triose phosphate isomerase, glutamate dehydrogenase, and open reading frame C4 sequences. Primers were designed to allow the specific amplification of the DNA of assemblage A or B and to generate products distinguishable by their melting curves or, after qPCR, by their sequences, sizes, or restriction patterns. The assays showed full specificity and detected DNA from a single trophozoite (4 to 8 target copies). We applied these assays, as well as a TaqMan assay that targets the beta-giardin gene, to genomic DNA extracted from 30 human stools and to Giardia cysts purified by immunomagnetic capture from the same samples. Simultaneous detection of both assemblages was observed in a large number of DNAs extracted from stools, and experiments on the cysts purified from the same samples showed that this was essentially attributable to mixed infections, as only one assemblage was detected when dilutions of cysts were tested. In a few cases, detection of both assemblages was observed even when single cysts were tested. This result, which suggests the presence of recombinants, needs to be confirmed using more accurate methods for cyst separation and enumeration. The assays described in this study can be used to detect Giardia cysts infectious to humans in samples from animals and in water and food.por
dc.identifier.citationAppl Environ Microbiol. 2010 Mar;76(6):1895-901. Epub 2010 Jan 15por
dc.identifier.issn0099-2240
dc.identifier.otherdoi:10.1128/AEM.02305-09
dc.identifier.urihttp://hdl.handle.net/10400.18/203
dc.language.isoengpor
dc.peerreviewedyespor
dc.publisherAmerican Society for Microbiologypor
dc.relation.publisherversionhttp://aem.asm.org/cgi/content/full/76/6/1895?view=long&pmid=20080999por
dc.subjectGiardiapor
dc.subjectPCRpor
dc.subjectInfecções Sistémicas e Zoonosespor
dc.titleGenotyping of Giardia duodenalis cysts by new real-time PCR assays for detection of mixed infections in human samplespor
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage1901por
oaire.citation.startPage1895por
oaire.citation.titleApplied and Environmental Microbiologypor
rcaap.rightsopenAccesspor
rcaap.typearticlepor

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