Heterogenity of Echinococcus canadensis genotype 6 − the main causative agent of cystic echinococcosis in Birjand, Eastern Iran

Phylogenetic Study of cox1 Gene in Echinococcus granulosus Sensu Lato Genotypes in Southwestern Iran

INTRODUCTION

Cystic echinococcosis (CE) is a serious global health concern. CE is an endemic zoonotic disease in Iran. The substantial genetic diversity of Echinococcus granulosus is closely linked to its life cycle, transmission mechanisms and pathogenesis. This study aimed to explore the phylogenetic structure of the genotypes of E. granulosus sensu lato (s.l.) in southwestern Iran (SWI).

METHODS

Seventy-two hydatid cyst samples were collected from various intermediate hosts, including goats, cattle, sheep, camels, buffalo and humans, primarily from the lungs, liver, spleen and heart of livestock slaughtered in local and industrial abattoirs, as well as from patients in several hospitals (Namazi, Golestan, Arvand and Shahid Beheshti) in southwestern Iran (Bushehr, Fars, Kohgiluyeh and Boyerahmad and Khuzestan provinces).

RESULTS

Sequence analysis revealed three genotypes of E. granulosus s.l. in the SWI: G1 (n = 69, 95.8%), G3(n = 1, 1.4%) and genotype like G6/G7 (n = 2, 2.8%). Twenty-one different haplotypes were identified in this study. According to the phylogenetic tree topology, the cox1 gene sequence similarities can be shown for some G1 and G6/G7 isolates in some vast areas, but these genotypes generally show a heterogeneous population worldwide. High similarity was shown between G3 isolates from some countries (Spain, Turkey, India and Iran) and different hosts (sheep, human and buffalo).

CONCLUSIONS

The presence of the G6/G7 genotype in the SWI may be due to the transmission of this genotype from other regions or the role of camel/wild boar and other possible intermediate hosts in the expansion of this genotype in the SWI. The results of the present study can be used in CE control programs, molecular epidemiology and phylogenetic studies in Iran and other countries for future goals.

The genetic variation of mitochondrial sequences and pathological differences of Echinococcus multilocularis strains from different continents

Alveolar echinococcosis is a lethal zoonotic disease caused by the fox tapeworm Echinococcus multilocularis. The parasite is widely distributed in the Northern Hemisphere and exhibits low genetic diversity among populations. To compare the differences among four E. multilocularis strains from different geographical locations, namely, Alaska (EM-AK), Japan (EM-JP), Xinjiang (EM-XJ), and Ningxia (EM-NX), their complete mitochondrial (mt) sequences were compared, and their induced pathological lesions were analyzed in mouse models. The complete mt sequence of EM-AK resulted in 0.84%-0.86% variation as compared with the other strains, which had a lower variation. Phylogenetic analysis and parsimony network indicated that EM-AK resulted in 30,000 years of evolutionary distance from the other three strains. EM-AK induced more pathological damage than the other three strains, which was likely to induce more host cell infiltration and acute granuloma in the liver. More importantly, EM-AK produced more protoscoleces than the other three strains, which may impact the transmission dynamics of the parasite. Given the geographical location of four strains, which is far from each other, and also the pathological differences, the strains of E. multilocularis are likely models for addressing the relationship and interfacial immune response between the host and the helminth.IMPORTANCEEchinococcus multilocularis is the causative agent of alveolar echinococcosis, which is considered the most serious parasitic disease in the Northern Hemisphere. There are many genotypes, but the pathogenic and mitochondria sequence and differences are still unclear. Therefore, this study showed both pathological and genetic differences between the four strains of E. multilocularis. EM-AK induced more severe immune responses and especially induced more host cell infiltration, which resulted in more severe granuloma in the liver. EM-JP has metacestode lesions morphologically closer to those of E. granulosus with clear cyst fluid. However, this strain produced much fewer protoscoleces (PSCs). Genetically, EM-AK is more distant from other strains.

Genetic characterization of human echinococcosis in Southern Punjab, Pakistan

Introduction

Echinococcosis is a neglected tropical zoonotic infection that affects both the human and livestock populations. In Pakistan, the infection is long-standing, but data on its molecular epidemiology and genotypic characterization in the southern Punjab region are limited. The aim of the current study was the molecular characterization of human echinococcosis in southern Punjab, Pakistan.

Methods

Echinococcal cysts were obtained from a total of 28 surgically treated patients. Patients' demographic characteristics were also recorded. The cyst samples were subjected to further processing to isolate DNA in order to probe the Nad1 and Cyt-b genes, followed by DNA sequencing and phylogenetic analysis for genotypic identification.

Results

The majority of the echinococcal cysts were from male patients (60.7%). The liver was the most commonly infected organ (60.71%), followed by the lungs (25%), spleen (7.14%), and the mesentery (7.14%). Molecular and genotypic identification through sequencing and phylogenetic tree analysis showed that most of the cysts (24/28, 85.7%) were caused by the species Echinococcus granulosus sensu stricto (E. granulosus s.s.) (G1 and G3), followed by Echinococcus multilocularis (E. multilocularis) and Echinococcus canadensis (E. canadensis) (G6/G7) (3/28, 10.8%, and 1/28, 3.5%, respectively).

Conclusion

The current study concluded that the majority of human infections were caused by E. granulosus s.s., followed by the E. multilocularis and E. canadensis species (G6/G7). Genotypic characterization among both human and livestock populations is needed to explore the genetic diversity of echinococcosis.

Genetic diversity and haplotype analysis of yak and sheep echinococcal cysts isolates from the mitochondrial cox1 gene in parts of Tibet, China

Echinococcosis, also known as hydatid disease, is caused by the metacestode stage of the species cluster Echinococcus granulosus sensu lato (E. granulosus s.l.). It is almost widespread worldwide, especially in countries and regions dominated by animal husbandry. It is a major parasitic disease that seriously endangers human health, public health safety, environmental safety, and the development of animal husbandry production in western China. In this study, the mitochondrial cox1 gene was used to analyze the genetic diversity and haplotype of bovine and sheep echinococcal cysts isolated in Tibet. Echinococcus granulosus sensu stricto (E. granulosus s.s., G1, G3) was still the dominant species in the infected samples of yak and sheep in some parts of Tibet. Through haplotype analysis, Hap_1 was deemed the dominant haplotype, 14 of the 20 haplotypes were similar to the reference sequence previously published in Genbank, and the rest of the 6 haplotypes were found for the first time. Through Tajima's D value, neutral test Fu's Fs analysis, and haplotype network map, it can be concluded that Echinococcus population expansion has occurred in Xigaze, Tibet. This study provides basic data for understanding the genetic characteristics, epidemiology, and control of echinococcosis in this area.

Genetic diversity of Echinococcus granulosus sensu lato in China: Epidemiological studies and systematic review

Cystic echinococcosis (CE) is a neglected tropical zoonosis caused by Echinococcus granulosus sensu lato (s.l.) and remains a major public health concern globally. Here, CE isolates (n = 3310) with clearly defined genotypes and geographical origins in China were retrieved through our epidemiological survey (2016-2020) and systematic review (1992-2020). Existing known genotypes of Echinococcus granulosus sensu lato (E. granulosus s.l.) except for G4 have been found in China, particularly on the Tibetan Plateau, where their genetic diversity is unique to that part of the world. According to the systematic review, genetic compositions of E. granulosus s.l. in China were as follows: E. granulosus (G1, G3), 98.3%; Echinococcus ortleppi (G5), 0.1%; Echinococcus intermedius (G6, G7), 1.4%; and Echinococcus canadensis (G8, G10), 0.2%. Specifically, G1 was responsible for 97.7% of infections and characterized by the broadest host ranges and geographic distributions. Our epidemiological results showed a relatively stable genetic composition of E. granulosus s.l. in sheep and yaks from three CE hyperendemic provinces (Xinjiang, Sichuan, Qinghai). A higher proportion of fertile cysts were found in sheep (287/406, 70.7%) than in yaks (28/184, 15.2%). During the past 29 years, 51 cox1 haplotypes of E. granulosus s.l. were endemic in China. The ancestral haplotype (Hap_2) remained the most common haplotype, 12 relatively common haplotypes were endemic and nine newly reported haplotypes were found during the survey. Overall, our results demonstrate that the compulsory immunization of sheep and the pilot EG95 vaccination campaign in yaks are well matched with the current genotypic situation. In addition to yaks, we advocate for more surveillance of CE isolates from pigs, cattle, goats and camels, since their roles in the transmission and reservation of E. granulosus s.l. have been largely ignored in China.

Echinococcus granulosus sensu lato Genotypes in Different Hosts Worldwide: A Systematic Review

INTRODUCTION

The aim of this study was to develop a synthesis of the evidence available regarding verified E. granulosus sensu lato (s.l.) genotypes in different species worldwide.

MATERIAL AND METHODS

A systematic review was performed including studies concerning genotypes of E. granulosus s.l. without language or genotyped method restriction, published between 1990 and 2020. A systematic search was carried out in Trip Database, BIREME, SciELO, LILACS, IBECS, PAHO-WHO, EMBASE, PubMed, Scopus, and WoS. Variables of interest were year of publication, country, number of samples, and hosts; genotypes, molecular marker, haplotypes and molecular biology techniques used. Descriptive statistics were applied.

RESULTS

2411 articles were analyzed, however 135 met the selection criteria, representing 8643 liver and lung samples. Of the samples selected 24% were human, the remaining samples pertained to non-human animal hosts; cattle and sheep prevailed with 28.6% and 26.6% of the studied samples, respectively. The reported evidence is mainly from Iran, Turkey, Argentina, China and Chile; with 50, 11, 6, 6 and 5 studies, respectively, published between 1992 and 2020 [most frequently during 2015-2020 (76/135 studies; 56.3%)]. The mitochondrial gene cox1 was generally sequenced and informative (91.8%). Genotypes most frequently identified were E. granulosus sensu stricto (s.s.) (83.2%).

CONCLUSIONS

Based on this overall evidence, it can be concluded that publications related to genotypes of E. granulosus s.l. are heterogeneous. E. granulosus ss accounts for the vast majority of the global burden of E. granulosus s.l. worldwide. Further studies including larger number of cases and adequate internal validity are required to specify the distribution of genotypes in various host species.

TRIAL REGISTRATION

PROSPERO CRD42018099827.

Sequence analysis, intra-genotyping variation, and phylogenetic study of nad1 gene in Echinococcus granulosus sensu lato genotypes from intermediate hosts in southwestern Iran

Cystic echinococcosis (CE) is caused by the larval stage of Echinococcus granulosus sensu lato (s. l.). The disease is cosmopolitan, and Iran is a highly endemic area for CE. This parasite exhibits high genetic diversity, which can be related to its life cycle, transmission, and pathogenesis. This study was aimed at determining the phylogenetic relationship and intra-genotyping variation of E. granulosus s.l. in a vast area in the southwest of Iran (SWI). Eighty hydatid cyst isolates of intermediate hosts (i.e., cattle, sheep, goat, buffalo, camel, and human) were collected. The sequence analysis of the nad1 gene exhibited the three genotypes of G1 (n = 70, 87.5%), G3 (n = 8, 10%), and G6/G7 (n = 2, 2.5%). Also, 16, 2, and 1 unique haplotypes were identified for the G1, G3, and G6/G7 genotypes, respectively. According to the phylogenetic tree topology, the nad1 gene similarities were found for some G1 isolates in some vast areas, and the G1 genotype showed a heterogeneous population worldwide. The only SWI G6/G7 haplotype was at a distant position in E. canadensis clade, indicating the notable difference of this haplotype from other isolates from Iran and other countries. The presence of the G6/G7 genotype in the SWI may be due to the transmission of the genotype from other regions or the role of camel/wild boar or other possible hosts in the expansion of this genotype in SWI. The results of the present study can be used in CE control programs, molecular epidemiology, and phylogenetic studies in Iran and other countries for future goals.

Echinococcoses in Iran, Turkey, and Pakistan: Old Diseases in the New Millennium

Echinococcosis is considered a cosmopolitan zoonosis caused by different species of small taeniid tapeworms of the genus Echinococcus and is regarded as a neglected zoonosis. Cystic and alveolar echinococcoses are endemic diseases of Tibetan, Pamir, and Iranian plateaus. All of the countries within the Iranian plateau are affected by echinococcosis. Pakistan, Turkey, and Iran are the three most populous countries of the region, in which echinococcosis is highly endemic. The three neighboring countries share strong cultural and socioeconomic ties. The present study aimed to provide a broad review of the status of cystic and alveolar echinococcosis, summarizing the current knowledge about geographical distribution, molecular epidemiology, and transmission dynamics of Echinococcus granulosus sensu lato and Echinococcus multilocularis in this region. Additionally, we aimed to understand disease burden and risk factors as basic requirements for establishing a surveillance system and planning prevention and control programs. A considerable body of information is available on different aspects of echinococcosis in this region; however, several information and research gaps need to be filled before planning control programs. None of the countries in the region have an elaborate echinococcosis control program. Effective control programs require multi/intersectoral coordination within a One Health approach with a long-term political and administrative commitment and enhanced international collaboration among the three countries.

Genotyping of the Echinococcus granulosus in Paraffin-Embedded Human Tissue Samples from Iran

PURPOSE

Cystic Echinococcosis (CE) is a medically important disease that is caused by the metacestodes of Echinococcus granulosus. Human hydatid is considered an endemic disease in specific regions of Iran. The goal of the present study was to determine the genetic diversity of E. granulosus from the paraffin-embedded human tissue samples which were collected from the endemic regions of Iran.

METHODS

Fifty-five formalin-fixed and paraffin-embedded hydatid cysts (FFPE) of humans, which had been removed surgically, were obtained from the South Khorasan and Sistan and Baluchistan provinces. These regions are related to the East and Southeast regions of Iran, respectively. The cox1 and nad1 genes from mitochondria were amplified from the extracted DNA and sequenced. The sequences were edited using the BioEdit software. Furthermore, phylogenetic and genetic diversity analyses were performed.

RESULTS

Sequencing of the cox1 and nad1 genes from the 44 CE samples was done successfully. Genetic analysis revealed that 38 (86.3%) and 6 (13.6%) of the isolates were G1- and G6-genotypes, respectively. In general, eight and six haplotypes were identified by cox1 and nad1 genes analysis, respectively. For G1 strains, the haplotype diversity index was higher for the cox1 gene (0.6 ± 0.07) in comparison with the nad1 gene (0.4 ± 0.09).

CONCLUSION

The findings of the present study showed that the sheep strain (G1) and the less important camel strain (G6) play the main roles in the transmission cycle of CE in the East and Southeast regions of Iran. Therefore, these results could be useful for managing the hydatid disease control programs in the studied and other similar areas.

The global status and genetic characterization of hydatidosis in camels (Camelus dromedarius): a systematic literature review with meta-analysis based on published papers

Hydatidosis is a potential zoonotic helminthic disease affecting a broad spectrum of mammals, including humans, worldwide. The current review was conducted to investigate the genotypic status and prevalence of hydatid disease in camels across the world. For the purpose of the study, the articles addressing the worldwide prevalence of hydatidosis in camels were searched in several English language databases. The search process resulted in the inclusion of 122 papers. Based on the data presented in the reviewed articles, the pooled prevalence of hydatid disease in camels across the world was measured at 23.75% (95% CI 20.15-27.55). Moreover, the subgroup analysis demonstrated significant differences in the overall prevalence of hydatidosis among camels based on year, geographic area, climate parameters, camel population, gender, infected organ, fertility rate of the cyst and laboratory diagnostic technique. Furthermore, the Echinococcus granulosus genotypes identified in camels with hydatidosis included G1, G2, G3, G1-G3, G5, G6, G7, G6-G7 and G6-G10, with G6 being the most common genotype throughout the world. The data obtained from the current study are central to the better conceptualization of the biological and epidemiological characteristics of E. granulosus s.l. genotypes around the world, which can be helpful in the planning and adoption of more comprehensive control strategies.

Environmental, climatic and host population risk factors of human cystic echinococcosis in southwest of Iran

BACKGROUND

Cystic echinococcosis (CE), a worldwide zoonotic disease, is affected by various biological and environmental factors. We investigated dog/livestock populations, climatic and environmental factors influencing the distribution of human CE cases in Fars province, southwest Iran.

METHODS

We mapped the addresses of 266 hospitalised CE patients (2004-2014) and studied the effects of different temperature models, mean annual rainfall and humidity, number of frosty days, slope, latitude, land covers, close proximity to nomads travel routes, livestock and dog densities on the occurrence of CE using geographical information systems approach. Data were analyzed by logistic regression.

RESULTS

In the multivariate model predicting CE, living in an urban setting and densities of cattle and dogs were the most important CE predictors, sequentially. Dry (rained) farm, density of camel and sheep, close proximity to nomads travel routes, humidity, and slope also were considered as the determinants of CE distribution, when analyzed independently. Slope had a negative correlation with CE while temperature, frost days and latitude were not associated with CE.

CONCLUSIONS

In our study, an urban setting was the most important risk factor and likely due to a combination of the high density of key life cycle hosts, dogs and livestock, a large human susceptible population and the high number of abattoirs. Farmland and humidity were highly suggestive risk factors and these conditions support the increased survival of Echinococcus granulosus eggs in the soil. These findings support the development of strategies for control of disease. More research is needed test optimal interventions.

Effects of geographical and climatic factors on cystic echinococcosis in south-western Iran

Cystic echinococcosis (CE) is caused by the larval form of Echinococcus granulosus that can cause serious health and economic problems in the endemic foci. CE is globally distributed in various climatic conditions from circumpolar to tropical latitudes. Iran is an important endemic area with a spectrum of weather conditions. The aim of this study was to determine the effects of geo-climatic factors on the distribution of livestock CE in south-western Iran (SWI) in 2016 to 2018. Data of livestock CE were retrieved from veterinary organizations of four provinces of SWI. The geo-climatic factors, including mean annual temperature (MAT), minimum MAT (MinMAT), maximum MAT (MaxMAT), mean annual rainfall (MAR), elevation, mean annual evaporation (MAE), sunny hours, wind speed, mean annual humidity (MAH), slope, frost days and land cover, were analysed using geographical information systems (GIS) approaches. The statistical analysis showed that MAR, frost days, elevation, slope and semi-condensed forest land cover were positively and MAE, MAT, MaxMAT, MinMAT and salt and salinity land cover were negatively correlated with CE occurrence. MAE was shown to be a predictive factor in the stepwise linear logistic regression model. In short, the current GIS-based study found that areas with lower evaporation were the main CE risk zones, though those with lower temperature and higher rainfall, altitude and slope, especially where covered with or in close proximity of semi-condensed forest, should be prioritized for consideration by health professionals and veterinarians for conducting control programmes in SWI.

Detection and genetic characterization of Echinococcus granulosus mitochondrial DNA in serum and formalin-fixed paraffin embedded cyst tissue samples of cystic echinococcosis patients

Cystic echinococcosis (CE) is a worldwide zoonotic disease caused by the larval stage of Echinococcus granulosus. We investigated the presence of E. granulosus-specific DNA in the serum of CE patients by detecting the cytochrome c oxidase I (cox1) and NADH dehydrogenase subunit I (nad1) mitochondrial genes. Serum and formalin-fixed paraffin embedded (FFPE) cyst tissue samples of 80 CE patients were analyzed. The extracted DNA of samples was submitted to PCR amplification of cox1 and nad1 genes, and products were sequenced and genotyped. Nineteen (23.8%; 95% CI 15.8-34.1) serum and 78 (97.5%; 95% CI 91.3-99.3) FFPE cyst tissue samples were successfully amplified with at least one gene. Echinococcus DNA was detected in the sera of 15.0% (95% CI: 8.8-24.4) and 10.0% (95% CI: 5.2-18.5) and in cyst tissue of 91.3% (95% CI: 83.0-95.7) and 83.8% (95% CI: 74.2-90.3) of 80 patients by cox1 and nad1 gene, respectively. Four genotypes of E. granulosus were distinguished in the CE patients, with predominance of genotype G1, followed by G3, G2, and G6. The finding of E. granulosus DNA in 23.8% of serum samples from CE patients confirmed that E. granulosus releases cell-free DNA into the circulatory system, but quantities may be inadequate for the diagnosis of CE. Genotype G1 predominance suggests the sheep-dog cycle as the primary route of human infection.

Cystic echinococcosis in Nigeria: first insight into the genotypes of Echinococcus granulosus in animals

Background

Cystic echinococcosis (CE) is a zoonosis caused by cestodes of Echinococcus granulosus (sensu lato) complex. In Nigeria, reports on the prevalence of CE, although limited, have been found to vary with location and host with higher prevalence and fertility rate observed in camels than other livestock. Until now, information regarding the molecular characteristics, genetic population structure, and genotypes of Echinococcus is lacking. Therefore, this study was aimed at addressing these gaps in knowledge.

Methods

We describe the genetic status of 31 Echinococcus isolates collected from slaughtered livestock (camels, cattle and goats) based on the full-length mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes.

Results

The resulting nucleotide sequences via the NCBI BLAST algorithm and Bayesian phylogeny of cox1 and cox1–nad1 genes using MrBayes v.3.1.2 showed that all isolates were clearly E. canadensis (G6/G7) and were 99–100% identical to previously reported G6/G7 haplotypes across Europe, Asia, North and East Africa.

Conclusions

Although, the G1 genotype is believed to be responsible for the majority of global CE burden, reports from a number of West African countries including Nigeria suggest that E. canadensis G6/G7 genotype could be the major causative agent of CE in the subregion. This study provides for the first time insight into the genetic population structure of Echinococcus species as well as implications for CE control in Nigeria.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3644-z) contains supplementary material, which is available to authorized users.

Genotyping and phylogenetic analysis of unusually located hydatid cysts isolated from humans in north-east Iran

Despite several studies conducted to determine the genotypes of cystic echinococcosis (CE) agents in humans and other intermediate hosts, the relationship between parasite genotype and clinical presentation of hydatidosis is yet to be well defined. The aim of this study was to compare the genotypes/haplotypes of CE agents of human extra-hepatopulmonary hydatid cysts and common hydatid cysts of the liver. A comparative analysis was carried out between partial cox1 sequences of ten extra-hepatopulmonary hydatid cysts, two liver cysts and reliable sequences from the GenBank database. All the studied hydatid cysts had the Echinococcus granulosus sensu stricto (G1-G2-G3) genotypes. The liver CE cysts were caused by common G1 genotype, while six of the extra-hepatopulmonary cysts had genotypes different from common G1 cysts. The sequences of these six isolates were identical to the G2 and G3 genotypes of E. granulosus sensu stricto; the kidney and peritoneum cysts and most of the brain cysts were identified as G2 genotype, while G3 genotype was only reported in a cyst belonging to the pelvic region. Given the observed differences between the sequences of hydatid cysts, it seems that the replacement of hydatid cysts in organs other than the liver and lungs can be related to their genotypes and probably intra-genotypic characteristics. It was hypothesized that in each geographic area, less frequent genotypes were likely to be more consistent with placement in the host's unusual organs.

A systematic review and meta-analysis of the genetic characterization of human echinococcosis in Iran, an endemic country

Human echinococcosis is an infectious disease caused by tapeworms belonging to the species Echinococcus. This parasite has a worldwide distribution and is considered a neglected tropical disease by the World Health Organization. Due to the diversity of Echinococcus spp. hosts, as well as variation in geographical, climatic, and socio-ethnic conditions, the question of the strains or genotypes of Echinococcus spp. that are involved in human infections is important. The aim of this study was to provide a summary of the available data on genotypes of Echinococcus obtained from the Iranian population. Four international databases (PubMed, Scopus, Science Direct, and Web of Science) and 4 Persian databases (Magiran, Scientific Information Database, Iran Medex, and IranDoc) were searched for cross-sectional studies that reported the genotypes of Echinococcus spp. in human echinococcosis cases using molecular methods in Iran through July 2018. The Newcastle-Ottawa Scale was used to assess the quality of the selected studies. A total of 559 cases of human cystic echinococcosis were reported in the 21 included articles. The majority of cases belonged to genotype G1 (89.2%; 95% confidence interval [CI], 80.1 to 95.8), genotype G6 (8.2%; 95% CI, 2.8 to 15.9), and genotype G3 (2.3%; 95% CI, 1.1 to 3.9). Since genotype G1 of Echinococcus appears to be the most prevalent genotype affecting humans in Iran, disease control initiatives aimed at sheep intermediate hosts may be the most beneficial. In addition, educational programs and serological screening in individuals may help reduce the national impact of the disease.

Comparison between Echinococcus granulosus sensu stricto (G1) and E. canadensis (G6) mitochondrial genes (cox1 and nad1) and their related protein models using experimental and bioinformatics analysis

BACKGROUND

Cystic echinococcosis (CE) as a zoonotic parasitic disease, remains a health challenge in many parts of the world. There are different species of Echinococcus granulosus sensu lato with different pathogenicity and host preferences.Different procedures have been applied for characterization of Echinococcus taxa in which two mitochondrial genes, cox1 and nad1 have been used more common. They have been able to differentiate E. granulosus sensu stricto and E. canadensis species in different hosts. The affinity of E. granulosus sensu stricto and E. canadensis species for localizing different organs seems to be different. To what such affinity and related pathogenicity could be related, is not known, so far. Bioinformatics analysis may be helpful to interpret such difference by investigating the genes and their related protein models between different species infecting human and animals. The current work was designed to study the differences between E. granulosus s.s. and E. canadensis species mitochondrial genes (cox1 and nad1) and related protein models of CE cysts by experimental and bioinformatics analysis.

MATERIALS AND METHODS

Different human and animal CE cysts were collected and their DNA was extracted and sequenced based on their cox1 and nad1 genes. In order to determine the E. granulosus s.s. and E. canadensis species of the samples, BLAST analysis was performed on sequenced genes. Three sequences were selected for analysis and were deposited in GenBank. Moreover, the sequence number of KT988116.1 which belonged to E. canadensis from our already deposited in GenBank was also selected. Alignment and phylogenetic analysis were performed on the sequences using BioEdit and MEGA7 software. The raw sequences of translated proteins belonged to the mentioned genes were obtained from Protein database in NCBI. The secondary structure was determined by PSIPRED Protein Sequence Analysis Workbench. The tertiary models of COX1 and NAD1 proteins in both genotypes were constructed using Modeler 9.12 software and their physicochemical features were computed using ProtParam tool in ExPASY server.

RESULTS

BLAST analysis on sequenced genes showed that the samples belonged to E. granulosus s.s. and E. canadensis species. These sequences were deposited in GenBank with accession numbers: JN579173.1, KF437811.1, and KY924632.1. The results showed that proteins of COX1 of E. granulosus s.s., COX1of E. canadensis, NAD1of E. granulosus s.s. and NAD1of E. canadensis species, consisted of 135, 122, 120 and 124 amino acids, respectively. The aligned sequences of translated proteins belonged to COX1 and NAD1 enzymes in E. granulosus s.s. and E. canadensis species were different; such that alignment COX1 sequence between E. granulosus s.s. and E. canadensis species showed that amino acids were different in 6 positions. This difference for NAD1 sequences were different in 19 positions. The secondary structure determined by PSIPRED showed differences in coil, strand and helix chains in COX1 and NAD1 proteins in E. granulosus s.s. and E. canadensis species. Comparison between three-dimensional structures (3D) of COX1 protein model in E. granulosus s.s. and E. canadensis species demonstrated an additional helix with two conserved iron binding sites in the COX1 protein of E. granulosus s.s. species.

CONCLUSION

E. granulosus s.s. and E. canadensis species differences are reflected in two important proteins: COX1 and NAD1. These differences are demonstrable in the 3D structure of proteins of both strains. So, the present study is adding to our understanding of the difference in molecular sequences between the E. granulosus s.s. (G1) and E. canadensis (G6) which may be used for interpreting the difference between the pathogenicity and localization affinity in these two important helminthic zoonosis.

The benefits of analysing complete mitochondrial genomes: Deep insights into the phylogeny and population structure of Echinococcus granulosus sensu lato genotypes G6 and G7

Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of the species complex Echinococcus granulosus sensu lato. Within this complex, genotypes G6 and G7 have been frequently associated with human CE worldwide. Previous studies exploring the genetic variability and phylogeography of genotypes G6 and G7 have been based on relatively short mtDNA sequences, and the resolution of these studies has often been low. Moreover, using short sequences, the distinction between G6 and G7 has in some cases remained challenging. The aim here was to sequence complete mitochondrial genomes (mitogenomes) to obtain deeper insight into the genetic diversity, phylogeny and population structure of genotypes G6 and G7. We sequenced complete mitogenomes of 94 samples collected from 15 different countries worldwide. The results demonstrated that (i) genotypes G6 and G7 can be clearly distinguished when mitogenome sequences are used; (ii) G7 is represented by two major haplogroups, G7a and G7b, the latter being specific to islands of Corsica and Sardinia; (iii) intensive animal trade, but also geographical isolation, have likely had the largest impact on shaping the genetic structure and distribution of genotypes G6 and G7. In addition, we found phylogenetically highly divergent haplotype from Mongolia (Gmon), which had a higher affinity to G6.