Sirtuin GdSir2.4 participates in the regulation of rRNA transcription in the Giardia duodenalis parasite

Background: The protozoan Giardia duodenalis, which causes giardiasis, is an intestinal parasite that commonly affects humans, mainly pre-school children. Although there are asymptomatic cases, the main clinical features are chronic and acute diarrhea, nausea, abdominal pain, and malabsorption syndrome. Little is currently known about the virulence of the parasite, but some cases of chronic gastrointestinal alterations post-infection have been reported even when the infection was asymptomatic, suggesting that the cathepsin L proteases of the parasite may be involved in the damage at the level of the gastrointestinal mucosa. Objective: The aim of this study was the in silico identification and characterization of extracellular cathepsin L proteases in the proteome of G. duodenalis. Methods: The NP_001903 sequence of cathepsin L protease from Homo sapienswas searched against the Giardia duodenalisproteome. The subcellular localization of Giardia duodenaliscathepsin L proteases was performed in the DeepLoc-1.0 server. The construction of a phylogenetic tree of the extracellular proteins was carried out using the Molecular Evolutionary Genetics Analysis software (MEGA X). The Robetta server was used for the construction of the three-dimensional models. The search for possible inhibitors of the extracellular cathepsin L proteases of Giardia duodenaliswas performed by entering the three-dimensional structures in the FINDSITEcomb drug discovery tool. Results: Based on the amino acid sequence of cathepsin L from Homo sapiens, 8 protein sequences were identified that have in their modular structure the Pept_C1A domain characteristic of cathepsins and two of these proteins (XP_001704423 and XP_001704424) are located extracellularly. Threedimensional models were designed for both extracellular proteins and several inhibitory ligands with a score greater than 0.9 were identified. In vitrostudies are required to corroborate if these two extracellular proteins play a role in the virulence of Giardia duodenalisand to discover ligands that may be useful as therapeutic targets that interfere in the mechanism of pathogenesis generated by the parasite. Conclusion: In silicoanalysis identified two proteins in the Giardia duodenalisprotein repertoire whose characteristics allowed them to be classified as cathepsin L proteases, which may be secreted into the extracellular medium to act as virulence factors. Three-dimensional models of both proteins allowed the identification of inhibitory ligands with a high score. The results suggest that administration of those compounds might be used to block the endopeptidase activity of the extracellular cathepsin L proteases, interfering with the mechanisms of pathogenesis of the protozoan parasite Giardia duodenalis.

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Molecular characterization of Giardia duodenalis and evidence for cross‐species transmission in Northern Argentina

Transboundary and Emerging Diseases ◽

10.1111/tbed.14220 ◽

2021 ◽

Author(s):

Sahana Kuthyar ◽

Martin M. Kowalewski ◽

Matthew Seabolt ◽

Dawn M. Roellig ◽

Thomas R. Gillespie

Keyword(s):

Molecular Characterization ◽

Giardia Duodenalis

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Multilocus Genotyping of Giardia duodenalis in Mostly Asymptomatic Indigenous People from the Tapirapé Tribe, Brazilian Amazon

Pathogens ◽

10.3390/pathogens10020206 ◽

2021 ◽

Vol 10 (2) ◽

pp. 206

Author(s):

Pamela Carolina Köster ◽

Antonio F. Malheiros ◽

Jeffrey J. Shaw ◽

Sooria Balasegaram ◽

Alexander Prendergast ◽

...

Keyword(s):

Triosephosphate Isomerase ◽

Gastrointestinal Symptoms ◽

Giardia Duodenalis ◽

Protozoan Parasite ◽

Indigenous Communities ◽

Brazilian Amazon ◽

Epidemiological Survey ◽

Small Subunit ◽

High Genetic Diversity ◽

Cross Sectional

Little information is available on the occurrence and genetic variability of the diarrhoea-causing enteric protozoan parasite Giardia duodenalis in indigenous communities in Brazil. This cross-sectional epidemiological survey describes the frequency, genotypes, and risk associations for this pathogen in Tapirapé people (Brazilian Amazon) at four sampling campaigns during 2008–2009. Microscopy was used as a screening test, and molecular (PCR and Sanger sequencing) assays targeting the small subunit ribosomal RNA, the glutamate dehydrogenase, the beta-giardin, and the triosephosphate isomerase genes as confirmatory/genotyping methods. Associations between G. duodenalis and sociodemographic and clinical variables were investigated using Chi-squared test and univariable/multivariable logistic regression models. Overall, 574 individuals belonging to six tribes participated in the study, with G. duodenalis prevalence rates varying from 13.5–21.7%. The infection was positively linked to younger age and tribe. Infected children <15 years old reported more frequent gastrointestinal symptoms compared to adults. Assemblage B accounted for three out of four G. duodenalis infections and showed a high genetic diversity. No association between assemblage and age or occurrence of diarrhoea was demonstrated. These data indicate that the most likely source of infection was anthropic and that different pathways (e.g., drinking water) may be involved in the transmission of the parasite.

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Re-Discovery of Giardiavirus: Genomic and Functional Analysis of Viruses from Giardia duodenalis Isolates

Biomedicines ◽

10.3390/biomedicines9060654 ◽

2021 ◽

Vol 9 (6) ◽

pp. 654

Author(s):

Gianluca Marucci ◽

Ilaria Zullino ◽

Lucia Bertuccini ◽

Serena Camerini ◽

Serena Cecchetti ◽

...

Keyword(s):

High Throughput Sequencing ◽

Diarrheal Disease ◽

Current Knowledge ◽

Biological Significance ◽

Giardia Duodenalis ◽

Protozoan Parasite ◽

Protein Translation ◽

Mass Spectrometry Analysis ◽

Animal Origin ◽

Spectrometry Analysis

Giardiasis, caused by the protozoan parasite Giardia duodenalis, is an intestinal diarrheal disease affecting almost one billion people worldwide. A small endosymbiotic dsRNA viruses, G. lamblia virus (GLV), genus Giardiavirus, family Totiviridae, might inhabit human and animal isolates of G. duodenalis. Three GLV genomes have been sequenced so far, and only one was intensively studied; moreover, a positive correlation between GLV and parasite virulence is yet to be proved. To understand the biological significance of GLV infection in Giardia, the characterization of several GLV strains from naturally infected G. duodenalis isolates is necessary. Here we report high-throughput sequencing of four GLVs strains, from Giardia isolates of human and animal origin. We also report on a new, unclassified viral sequence (designed GdRV-2), unrelated to Giardiavirus, encoding and expressing for a single large protein with an RdRp domain homologous to Totiviridae and Botybirnaviridae. The result of our sequencing and proteomic analyses challenge the current knowledge on GLV and strongly suggest that viral capsid protein translation unusually starts with a proline and that translation of the RNA-dependent RNA polymerase (RdRp) occurs via a +1/−2 ribosomal frameshift mechanism. Nucleotide polymorphism, confirmed by mass-spectrometry analysis, was also observed among and between GLV strains. Phylogenetic analysis indicated the occurrence of at least two GLV subtypes which display different phenotypes and transmissibility in experimental infections of a GLV naïve Giardia isolate.

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Comparative analysis of routine parasitological methods for recovery of cysts, molecular detection, and genotyping of Giardia duodenalis

European Journal of Clinical Microbiology & Infectious Diseases ◽

10.1007/s10096-021-04280-9 ◽

2021 ◽

Author(s):

Renata Coltro Bezagio ◽

Cristiane Maria Colli ◽

Liara Izabela Lopes Romera ◽

Caroline Rodrigues de Almeida ◽

Érika Cristina Ferreira ◽

...

Keyword(s):

Comparative Analysis ◽

Molecular Detection ◽

Giardia Duodenalis

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Molecular Characterization of Giardia duodenalis in Children and Adults Sampled in Algeria

Microorganisms ◽

10.3390/microorganisms9010054 ◽

2020 ◽

Vol 9 (1) ◽

pp. 54

Author(s):

Salem Belkessa ◽

Daniel Thomas-Lopez ◽

Karim Houali ◽

Farida Ghalmi ◽

Christen Rune Stensvold

Keyword(s):

Real Time ◽

Molecular Characterization ◽

Real Time Pcr ◽

Intestinal Parasites ◽

Giardia Duodenalis ◽

Specific Pcr ◽

Stool Samples ◽

Pcr Targeting ◽

Assemblage B

The molecular epidemiology of giardiasis in Africa remains unclear. A study was carried out across four hospitals in Algeria. A total of 119 fecal samples from 55 children, 37 adults, and 27 individuals of undetermined age, all scored positive for intestinal parasites by microscopy, and were screened by real-time PCR for Giardia. Molecular characterization of Giardia was performed by assemblage-specific PCR and PCR targeting the triose phosphate isomerase gene (tpi). Of the 119 samples, 80 (67%) were Giardia-positive by real-time PCR. For 48 moderately-highly real-time PCR-positive samples, tpi genotyping assigned 22 samples to Assemblage A and 26 to Assemblage B. Contrary to Assemblage A, Assemblage B exhibited substantial genetic diversity and allelic heterozygosity. Assemblage-specific PCR proved to be specific for discriminating Assemblage A or B but not as sensitive as tpi genotyping. We confirmed that real-time PCR is more sensitive than microscopy for detecting Giardia in stool samples and that robust amplification and sequencing of the tpi gene is feasible when moderate-to-strongly real-time PCR-positive samples are used. This study is one of the few performed in Africa providing genotyping data on Giardia infections in humans. Both assemblages A and B were commonly seen and not associated with specific sociodemographic data.

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