Molecular characterization of Brazilian human Giardia duodenalis isolates using isoenzyme and random amplified polymorphic DNA analysis

Genetic diversity and molecular diagnosis of Giardia

Giardia is a genus of flagellated protozoan parasites that infect the small intestine of humans and animals, causing the diarrheal illness known as giardiasis. Giardia exhibits significant genetic diversity among its isolates, which can have important implications for disease transmission and clinical presentation. This diversity is influenced by the coevolution of Giardia with its host, resulting in the development of unique genetic assemblages with distinct phenotypic characteristics. Although panmixia has not been observed, some assemblages appear to have a broader host range and exhibit higher transmission rates. Molecular diagnostic methods enable researchers to examine the genetic diversity of Giardia populations, enhancing our understanding of the genetic diversity, population structure, and transmission patterns of this pathogen and providing insights into clinical presentations of giardiasis.

Isoenzyme profiles and phylogenetic analysis of Giardia duodenalis isolates from Iranian patients

The main objective of this study was to characterize the Giardia duodenalis isolates from Iranian patients in Fars Province, south of Iran by biochemical and molecular methods. Fifteen mass cultivated of G. duodenalis isolates in modified TYI-S-33 medium were analyzed using isoenzyme electrophoresis and PCR genotyping. Polyacrylamide gel electrophoresis (PAGE) of five different enzyme systems was used to characterize isolates: (i) glucose-6-phosphate dehydrogenase, (ii) glucose phosphate isomerase, (iii) malate dehydrogenase, (iv) malic enzyme, and (v) phosphoglucomutase. As well, a fragment of the SSU-rDNA (292 bp) gene was amplified by PCR using the primers RH11 and RH4. The sequencing of the PCR products and phylogenetic tree were performed. The isoenzyme electrophoretic profiles divided fifteen G. duodenalis isolates into four zymodemes. G6PD, GPI, MDH, ME, and PGM enzyme systems showed 1, 2, 2, 3, and 3 enzyme pattern, respectively. G6PD isoenzyme pattern had the most homogeneity, while isoenzyme patterns of ME and PGM had the most heterogeneity in our study. Genotyping results indicated that the zymodemes 1-4 were categorized in assemblage A based on the SSU-rDNA gene. Phylogenetic analysis showed that all four zymodemes were distributed within the cluster of assemblage A. Our results indicated that both isoenzyme and DNA analyses were useful to characterize the isolates of Giardia and distinguishing various zymodemes and assemblages. It could be suggested that the genetic diversity among isoenzymes profiles of G. duodenalis may explain the variable clinical manifestations, pathogenicity, host response, drug susceptibility, and treatment efficacy of human giardiasis.

Comparative study of effects of assemblages AII and BIV of Giardia duodenalis on mucosa and microbiota of the small intestine in mice

AIMS

Giardiasis is one of the major causes of diarrhea worldwide and its symptoms vary in intensity, which can be attributed to different parasite assemblages. The goal of the present study was to compare the effects of infection caused by assemblages AII and BIV ofGiardia duodenalis on the response of the small intestine, microbiota, and behavioral parameters in mice.

MAIN METHODS

Swiss mice were infected with assemblages AII and BIV of G. duodenalis for 15 days. Leucometry, pain, intestinal microbiota and histological parameters of the duodenum and jejunum were evaluated in the experimental groups.

KEY FINDINGS

Both assemblages modified the composition of the intestinal microbiota. Infection with assemblage AII promoted leukocytosis, reflected by increasing number of polymorphonuclear cells, intraepithelial lymphocytes and pain-related behavior, indicating that this was the more aggressive assemblage with regard to its effects on the intestinal mucosa and duodenum.

SIGNIFICANCE

The specific assemblage of the parasite is an important parameter that affects symptomatology in the host.

Simplified protocol for DNA extraction and amplification of 2 molecular markers to detect and type Giardia duodenalis

We evaluated the ability of 3 kits: QIAmp® DNA stool mini kit (Qiagen, Hilden, Germany), PureLink PCR Purification®, and PureLink™ Genomic DNA® (Invitrogen, Carlsbad, CA, USA) for DNA extraction, and of 2 molecular markers (heat shock protein [HSP] and β-giardin genes) for detection and genotyping of Giardia duodenalis stool samples. The detection and typing limits of the markers were determined by the DNA concentration of trophozoites and cysts and were tested in 26 clinical samples. Of the 3 kits tested, the PureLink PCR Purification gave the best results when tested with clinical samples with low, intermediate, and high numbers of cysts. The DNA extracted from trophozoites and cysts was diluted successively in 1:2 ratios until it was no longer possible to observe the amplified product in polyacrylamide gel. Similarly, a suspension of cysts was diluted until no cysts were observed, and then the DNA was extracted. The amount of DNA of trophozoites and cysts for the typing of the parasite was smaller for the HSP marker than for β-giardin. Combined use of both markers allowed us to detect DNA of Giardia in parasitologically positive samples in a higher percentage (75%) than the results obtained for each marker and in 1 parasitologically negative sample, indicating that this combination increased the potential to accurately detect and genotype this parasite. We also concluded that the HSP marker has a higher limit of detection and typing than the β-giardin marker and that the DNA extraction method tested for G. duodenalis is simpler and more efficient than those that are currently in use and can be applied on a large scale.

Giardia duodenalis: genotypic comparison between a human and a canine isolates

INTRODUCTION

Evidence suggests that giardiasis is a zoonotic disease. The present work aimed to evaluate the genetic identity of Giardia duodenalis isolated from human and dog fecal samples from Belo Horizonte.

METHODS

Human and dog fecal samples were cultured for isolation of G. duodenalis. To determine the genotype of the isolates, primers that amplify a specific region in rRNA of the protozoan were used.

RESULTS

Two G. duodenalis isolates were obtained, which belong to the subgroup A genotype.

CONCLUSIONS

These findings suggest that the transmission of giardiasis follows a zoonotic pattern.

Molecular identification of Giardia duodenalis isolates from humans, dogs, cats and cattle from the state of São Paulo, Brazil, by sequence analysis of fragments of glutamate dehydrogenase (gdh) coding gene

The nucleotide sequence of glutamate dehydrogenase (gdh) coding genes were obtained from cysts of Giardia duodenalis isolated from feces of naturally infected cats (n=19), dogs (n=27), humans (n=37) and cattle (n=5). The samples were from several municipalities within the state of São Paulo, Brazil and were collected from January 2004 to August 2006. Sequences analysis of the 37 specimens recovered from humans revealed 29 G. duodenalis assemblage AII and 8 G. duodenalis assemblage B. Among samples from cats, 11 were classified into assemblage F and 8 into assemblage AI. Only the host-adapted assemblages C and D were detected in samples from dogs (7 and 20, respectively). Among the samples from cattle, the genotype livestock was found in four samples and the assemblage AI was detected in one sample. The molecular identification of assemblages of G. duodenalis isolates from different hosts reveals that genetic diversity of this protozoon in Brazil is similar to that of Giardias from other parts of the world.

Classification of Giardia duodenalis parasites in Turkey into groups A and B using restriction fragment length polymorphism

PCR-RFLP (restriction fragment length polymorphism) analysis was used to determine the relation of Giardia duodenalis Groups A and B. Of these, 17 (85%) were found as Group A in symptomatic cases; 22 (92%) were Group B in asymptomatic cases by using PCR-RFLP (p < 0.001). Interestingly, 5 (83%) were Group A in examination of endoscopy aspirates of symptomatic cases, as 5 (83%) were Group B in asymptomatic cases.