Characterization of Fasciola hepatica genotypes from cattle and sheep in Iran using cytochrome C oxidase gene (CO1)

Multiplex PCR and Sequence Analysis to Investigate Genetic Diversity of Fasciola Isolates from Cattle and Sheep in Turkey

Fasciolosis is a highly prevalent helminthic infection caused by Fasciola hepatica and F. gigantica. With the aim of identifying hybrid Fasciola flukes, multiplex PCR was performed to amplify the pepck gene. Furthermore, to determine Fasciola haplotypes, mitochondrial nad1 gene was amplified and sequenced, and phylogenetic analyses were performed. Adult Fasciola isolates were collected from 51 cattle and 51 sheep, genomic DNA was isolated, and one-step multiplex PCR was subsequently performed to amplify pepck. Isolates that generated a 510 bp band were identified as F. gigantica, those that generated a 241 bp band were identified as F. hepatica, and those that generated both bands were identified as hybrid (aspermic) flukes. Multiplex PCR data identified four isolates as F. gigantica and 84 as F. hepatica. Fourteen hybrid isolates (five cattle and nine sheep) were identified. On unidirectional DNA sequence analysis of nad1 PCR products, three sequences were identified as F. gigantica and 99 as F. hepatica. In addition, only 4 of 87 haplotypes detected for F. hepatica nad1 sequences were found to be previously reported, while the remaining 83 are unique to this study. To summarize, this study is the first to report the existence of hybrid Fasciola flukes and 83 unique haplotypes of F. hepatica in Turkey.

Identification and Genetic Characterization of Fasciola hepatica Isolated from Cattle in Jeddah, Saudi Arabia Based on Sequence Analysis of Mitochondrial (COI) Gene

Background

In Saudi Arabia, more than US$ 0.2 million annual losses are caused by liver condemnations due to fascioliasis. Data obtained from the genetic characterization of Fasciola population sheds light on parasite transmission which could eventually help in development of effective parasite control measures. So, the aim of this study was to investigate the genetic diversity of Fasciola spp. isolated from cattle in Saudi Arabia by sequence analyses of COI gene.

Materials and Methods

A total of 325 cows slaughtered at the central municipal abattoir in Jeddah city, Jeddah Province, Saudi Arabia were examined for fascioliasis in the period from 1^st of June to 1^st of July 2020. DNA was extracted from adult Fasciola worms and used for PCR and DNA sequence using a primer pair targeting COI gene. Analysis of the obtained sequences was done using BLAST search and phylogenetic analysis.

Results

Bovine fascioliasis was diagnosed in 18 out of 325 cattle (5.5%). Forty-eight flukes were extracted from infected animals and DNA was successfully amplified from all flukes. Overall 12 different DNA sequences were obtained. BLAST search showed that all obtained sequences were F. hepatica and had >97% similarity with F. hepatica isolates from Tanzania, Europe and Iran. Phylogenetic analysis of the obtained sequences showed that Fasciola isolates from the current study were clustered in one subclade closely related to isolates from North and South Africa and Italy.

Conclusion

Reports on the molecular characterization of Fasciola spp. in Saudi Arabia are limited. In the current study, our findings showed that F. hepatica was the only Fasciola species parasitizing cattle in Jeddah city, Saudi Arabia. Further studies using a large number of samples from different localities in Saudi Arabia are needed to provide data that will help the development of control measures against fascioliasis.

Checklist of digenean trematodes of Iran

Digeneans are an important class of trematodes which infect variety of animals ranging from vertebrates (mainly final hosts) to invertebrates (mainly as intermediate hosts). Additionally, some of these parasites are zoonotic and one health importance. Diversity of digeneans in Iran and reports of several zoonotic cases show the importance of these parasites in this country. This is the checklist of digenean parasites reported from Iran representing a total of 118 species, from 105 genera, 43 families, 21 subfamilies, and 3 orders that are reported from 139 species of different hosts including humans. Some of the most important final number of families, genera, and species reported in Iran fauna include: Fasciolidae, Genus: Fasciola, Fasciola gigantica, Fasciola hepatica, Family: Dicrocoeliidae, Genus: Dicrocoelium, Dicrocoelium dendriticum, Family: Diplostomidae, Genus: Diplostomum, Diplostomum spathaceum, Family: Heterophyidae, Genus: Haplorchis, Haplorchis taichui, Family: Notocotylidae, Genus: Notocotylu, Notocotylus aegyptiacus, Family: Bucephalidae, Genus: Rhipidocotyle, Rhipidocotyle illense.

Molecular Characterization of Fasciola spp. from a Donkey (Equus asinus) Using Partial Sequencing of cox1 and nad1

Background

Fasciola hepatica as an important parasite affects health of humans and animals in some tropical and subtropical areas of the world, including Iran. Little is known about the molecular diversity of Fasciola in Equidae. Therefore, this study aimed to characterize the genetic polymorphisms among parasites.

Methods

Eight adult Fasciola spp. isolates were collected from a working donkey after necropsy in Shiraz, southwestern Iran, in 2018. Primarily, various parameters were measured morphologically. Subsequently, DNA was extracted from each fluke and molecular markers of cytochrome C oxidase (cox1) and NADH dehydrogenase 1(nad1) from individual Fasciola isolates were amplified using PCR assay and sequence data were employed for molecular and phylogenetic analysis. Genetic diversity between isolates was evaluated by comparing the sequences of these two mitochondrial regions.

Results

Based on the morphological and analyzed mitochondrial sequences, all of eight donkey isolates (100%) were identified as F. hepatica. Moreover, nine and five nucleotide polymorphisms were identified in the cox1and nad1 region sequences, respectively.

Conclusion

Accordingly, phylogenetic data revealed five and four haplotypes among donkey isolates based on the cox1and nad1 markers. Similarly, some of these haplotypes have been previously reported from different host species in Iran as well as all around the world.

Fasciola Species Introgression: Just a Fluke or Something More?

The threats posed by a range of viral and bacterial zoonotic diseases inevitably receive renewed attention in the wake of global pandemic events due to their overt and devastating impacts on human health and the economy. Parasitic zoonoses, however, many of which affect millions of people each day, are frequently ignored. In the case of fasciolosis, caused by infection with Fasciola hepatica or Fasciola gigantica, this oversight has allowed for the expansion of areas of parasite sympatry and thus increased the incidence of hybridization and possible introgression between the two species. Here we highlight how an increased demand for animal-derived protein, combined with a lack of appropriate tools for detection of these events, is changing the status quo of these zoonotic parasites.

Increased demand for animal-derived protein from Fasciola hepatica-endemic countries has led to a growing number of reports of hybridization between F. hepatica and Fasciola gigantica in Southeast Asia.

Hybridization and eventual introgression have been reported in a range of protozoan, helminth, and arthropod parasites and act as important drivers of evolutionary change and adaptation.

Introgression between Fasciola spp. remains unproven but has potentially serious human and animal health consequences as seen in other parasites.

New tools for the characterization of hybridization and introgression events between Fasciola spp. are needed.

Molecular Confirmation of a Fasciola gigantica × Fasciola hepatica Hybrid in a Chadian Bovine

Fascioliasis is a zoonotic infection of humans and, more commonly, ruminants. It is caused by 2 liver fluke species, Fasciola hepatica and Fasciola gigantica, which differ in size. The traditional morphological methods used to distinguish the 2 species can be unreliable, particularly in the presence of hybrids between the 2 species. The development of advanced molecular methods has allowed for more definitive identification of Fasciola species, including their hybrids. Hybrids are of concern, as it is thought that they could acquire advantageous traits such as increased pathogenicity and host range. In 2013, we collected flukes from Fasciola-positive cattle, sheep, and goats slaughtered in 4 Chadian abattoirs. DNA from 27 flukes was extracted, amplified, and analyzed to identify species using the ITS1+2 locus. Twenty-six of the 27 flukes were identified as F. gigantica, while the remaining fluke showed heterozygosity at all variable sites that distinguish F. hepatica and F. gigantica. Cloning and sequencing of both alleles confirmed the presence of 1 F. hepatica and 1 F. gigantica allele. To our knowledge, this is the first unambiguous, molecular demonstration of the presence of such a hybrid in a bovine in sub-Saharan Africa.

Genetic diversity of Fasciola hepatica in Austria

The worldwide occurring common liver fluke Fasciola hepatica can infect humans and animals and leads to considerable illness and economic loss annually. The aim of this study was to determine the genetic diversity of F. hepatica in Austria. In total, 31 adult flukes isolated from cattle from various regions in Austria were investigated for their cytochrome oxidase subunit 1 (cox1) and nicotinamide dehydrogenase subunit 1 (nad1) gene sequences. It was shown that Austrian isolates of F. hepatica reveal extensive genetic diversity. To the best of our knowledge, these are the first data on the diversity of F. hepatica in Austria.

Morphologic and molecular analysis of Dicrocoelium dendriticum species from Iranian native sheep

Dicrocoeliosis is a worldwide parasitic disease of ruminants which affects the liver. In this current study, the phylogenic pattern of Dicrocoelium species in Iranian native sheep from three different geographical regions was investigated by investigating a 520 bp fragment of mitochondirial NAD1 gene. The analysis of the NAD1 oligo nucleotide sequences from 10 D. dendriticum (GenBank accession numbers: MG889399 to MG889408) revealed few non-significant differences, suggesting limited application for NAD1 gene as a biomarker for study of genetic variation in Dicrocoelium. The morphometrical study also showed a significant relationship for the several morphometric indices among the Dicrocoelium spp. isolates from different regions of Iran.

Multigene typing and phylogenetic analysis of Fasciola from endemic foci in Iran

Fasciolosis is a public health problem originally transmitted from livestock. Although molecular analysis of the nuclear and mitochondrial genes allow discrimination between the two known species of Fasciola, F. hepatica and F. gigantica, these markers do not permit the detection of hybrid forms. On the other hand, molecular analysis of the pepck and pold genes from Fasciola do permit the detection of hybrid isolates and this study has not yet been performed on specimens from human and domesticated animals in Iran. Therefore, the aim of this study was to molecularly analyze Fasciola isolates using both conventional and the two new genetic markers mentioned above. Fifty-three adult Fasciola worms were isolated from the livers of 28 domesticated animals, including sheep, cattle and goat. Moreover, an adult worm was obtained from the bile duct of an infected woman during endoscopic retrograde cholangio-pancratography (ERCP). Targeted fragments from the ITS-1, NDI and COX1 genes were amplified using specific primers. PCR products were sequenced and genetically analyzed using MEGA v.7 and DnaSP software. Additionally, the pepck and pold regions were amplified and analyzed using multiplex PCR and RLFP-PCR, respectively. Multiple alignment of sequenced fragments showed highest similarity among the ITS-1 sequences isolated from all four hosts in comparison to the other genes. Furthermore, sequence diversity across the COX1 was higher than the NDI and ITS-1. Diversity among sequences isolated from cattle was higher than those from sheep and goat in all three genes. Tajima's D and Fu's Fs were negative and statistically significant for all the genes except ITS-1. Phylogenetic trees showed that the human F. hepatica isolate was closer to sheep isolates. The results of the pepck and pold analyses showed that all isolates were F. hepatica and there were no hybrid forms among samples. The molecular analyses corroborated this finding.

New insight into genetic variation and haplotype diversity of Fasciola hepatica from Algeria

The liver fluke Fasciola hepatica is the main cause of fasciolosis in North Africa leading to significant economic losses and public health problems. In this study, the ribosomal internal transcribed spacer (ITS), cytochrome c oxidase I (COI), the mitochondrial region spanning the COI-trnT-rrnL, and the NADH dehydrogenase subunit I (NADI) markers were used to characterize Fasciola flukes from Algeria. Fasciola appeared widespread from the east to the west of Algeria. Among 1701 sampled cattle from 8 Algerian provinces, 5% were infected. Using morphological and morphometric analysis, one morphotype of Fasciola was observed. Nuclear ITS marker indicated that all collected flukes belong to F. hepatica. Multiple alignments of ITS dataset revealed two haplotypes, one described here for the first time. Analysis of molecular variance (AMOVA) of mitochondrial markers revealed weak population structure in Algeria. Mismatch distributions, neutrality tests, and median-joining network analysis all were compatible with a recent expansion of Algerian F. hepatica population. Fasciolosis appeared common in Algerian cattle, it seems that the absence of control strategy coupled to the favorable Mediterranean climate may lead to a reconstruction and dispersion of its populations. This study provides important results concerning the genetic characterization and variability of F. hepatica in Algeria as well as the significant role of cattle importation in shaping its dispersal route worldwide.

A new method for laboratory rearing of Galba truncatula, the intermediate host of Fasciola hepatica

In this study a relatively large and open top aquarium was designed, constructed and introduced as a suitable habitat for nutrition, growth and development as well as for egg laying and breeding of Galba truncatula under laboratory conditions. The soil and water used in the aquarium were collected from the locality in which the snails were collected. The aquarium was placed in a laboratory with temperature of 18-32 ºC and relative humidity of 22-37% respectively, according to the season. The artificial light was controlled by a light timer, giving 12 h of light and 12 h of darkness. The snails were fed with dried lettuce leaves, Cyperus alternifolius (aquatic plant), Spirulina (algae), Orthotrichum rupestre (moss) and cuttlebone (a supplementary source of calcium). Approximately five weeks after the start of study, there was evidence of reproduction and success in rearing of G. truncatula by the appearance of eggs and small snails (0.1-0.5 mm) in the aquarium. In conclusion, large scale laboratory rearing of G. truncatula is a feasible task. The method may be improved by balancing the temperature and relative humidity as well as by optimizing the soil type, the water quality and the type of food.

Genetic diversity of Fasciola spp. isolates from northern part of Iran: comparison with southwestern isolates

Animal and human fascioliasis is a health and economic problem in few of tropical and subtropical areas of the world, including Iran. The present study aimed to determine the genotype diversity of Fasciola isolates in different hosts from Gilan province, northern Iran, and compare it with those isolates from southwestern Iran. Forty-eight adult Fasciola spp. were collected from cattle, sheep, and goats from slaughterhouse in Talesh, north of Iran. DNA was extracted from each fluke and PCR-RFLP was used to find out the species of the isolates. The ribosomal ITS1 and ITS2, and mitochondrial genes of NDI and COI from individual Fasciola isolates of each host were PCR-amplified and the PCR products were sequenced. Genetic variation within and between the isolates was evaluated by comparing the sequences of ribosomal and mitochondrial genes. For analysis of phylogenetic diversity of the flukes, phylogenetic trees were constructed, using ITS1, ITS2, NDI, and COI sequences of the isolates. Based on PCR-RFLP profile, 5 (22.7%) of the total of sheep isolates and 18 (90%) of cattle isolates were identified as F. gigantica and other remaining samples from sheep, cattle and goats were identified as F. hepatica. Based on ITS1 and ITS2 sequences, six and seven nucleotide polymorphism were respectively noted in the isolates. On the other hand, CO1 region sequences showed considerable variation, which laid Talesh (north) isolates in a separate cluster. Findings of the study showed that the sequences of CO1 isolates from north and southwest have substantial differences mainly in CO1 region.

First genetic characterization of Fasciola hepatica in Argentina by nuclear and mitochondrial gene markers

Fasciola hepatica is a trematode showing genetic variation among isolates from different regions of the world. The objective of this work was to characterize for the first time F. hepatica isolates circulating in different regions of Argentina. Twenty-two adult flukes were collected from naturally infected bovine livers in different areas from Argentina and used for DNA extraction. We carried out PCR amplification and sequence analysis of the ribosomal internal transcribed spacer 1 (ITS1), mitochondrial nicotinamide adenine dinucleotide dehydrogenase subunits 4 and 5 (nad4 and nad5) and mitochondrial cytochrome c oxidase subunit I (cox1) genes as genetic markers. Phylogenies were reconstructed using maximum parsimony algorithm. A total of 6 haplotypes were found for cox1, 4 haplotypes for nad4 and 3 haplotypes for nad5. The sequenced ITS1 fragment was identical in all samples. The analyzed cox1 gene fragment is the most variable marker and is recommended for future analyses. No geographic association was found in the Argentinean samples.

Genetic homogeneity of Fascioloides magna in Austria

The large American liver fluke, Fascioloides magna, is an economically relevant parasite of both domestic and wild ungulates. F. magna was repeatedly introduced into Europe, for the first time already in the 19th century. In Austria, a stable population of F. magna has established in the Danube floodplain forests southeast of Vienna. The aim of this study was to determine the genetic diversity of F. magna in Austria. A total of 26 individuals from various regions within the known area of distribution were investigated for their cytochrome oxidase subunit 1 (cox1) and nicotinamide dehydrogenase subunit 1 (nad1) gene haplotypes. Interestingly, all 26 individuals revealed one and the same haplotype, namely concatenated haplotype Ha5. This indicates a homogenous population of F. magna in Austria and may argue for a single introduction. Alternatively, genetic homogeneity might also be explained by a bottleneck effect and/or genetic drift.

Controversial aspects of the life cycle of Fasciola hepatica

Fasciola hepatica is a well-known helminth parasite, with significant economic and public health importance all over the world. It has been known since more than 630 years ago and a considerable research work has been carried out on the life cycle of this important parasite. In the hepatic phase of the life cycle of F. hepatica, it is assumed that the young flukes, after about 6-7 weeks of migration in the liver parenchyma, enter into the bile ducts of the definitive hosts and become sexually mature. Even though the secretion of cysteine peptidases including cathepsin L and B proteases by F. hepatica may justify this opinion, because of several scientific reasons and based on the experimental studies conducted in different animals (reviewed in this article), the entry of parasites into the bile ducts, after their migration in the liver parenchyma seems to be doubtful. However, considering all the facts relating to the hepatic and biliary phases of the life cycle of F. hepatica, two alternative ideas are suggested: 1) some of the migrating juvenile flukes may enter into the bile ducts immediately after reaching the liver parenchyma while they are still very small, or 2) when newly excysted juvenile flukes are penetrating into the intestinal wall to reach the liver through the abdominal cavity, a number of these flukes may enter into the choleduct and reach the hepatic bile ducts, where they mature. According to the previously performed natural and experimental studies in different animals and human beings, the supporting and opposing evidences for the current opinion as well as the evidences that might justify the two new ideas are reviewed and discussed briefly. In conclusion, our present knowledge about the time and quality of the entry of F. hepaticas into the bile ducts, seems to be insufficient, therefore, there are still some dark corners and unknown aspects in this field that should be clarified.

Transcriptomic Analysis of Ovaries from Pigs with High And Low Litter Size

Litter size is one of the most important economic traits for pig production as it is directly related to the production efficiency. Litter size is affected by interactions between multiple genes and the environment. While recent studies have identified some genes associated with prolificacy in pigs, transcriptomic studies of specific genes affecting litter size in porcine ovaries are rare. In order to identify candidate genes associated with litter size in swine, we assessed gene expression differences between the ovaries of Yorkshire pigs with extremely high and low litter sizes using the RNA-Seq method. A total of 1 243 differentially expressed genes were identified: 897 genes were upregulated and 346 genes were downregulated in high litter size ovary samples compared with low litter size ovary samples. A large number of these genes related to steroid hormone regulation in animal ovaries, including 59 Gene Ontology terms and 27 Kyoto Encyclopedia of Genes and Genomes pathways involved in steroid biosynthesis and ovarian steroidogenesis. From these differentially expressed genes, we identified a total of 11 genes using a bioinformatics screen that may be associated with high litter size in Yorkshire pigs. These results provide a list of new candidate genes for porcine litter size and prolificacy to be further investigated.

Intraspecific mitochondrial DNA variation of Fasciola hepatica eggs from sheep with different level of anthelmintic resistance

In the current study, Fasciola hepatica strains of sheep with different degrees of resistance to anthelmintics were analyzed by sequencing the cytochrome C oxidase (COX1) and the NADH dehydrogenase (NAD1) subunits. The strains were as follows: LS, susceptible to all drugs tested; CS, resistant to albendazole and triclabendazole; and SV, resistant to albendazole and clorsulon. The molecular characterization was done in eggs recovered from sheep infected by LS and CS. In relation to SV, eggs were recovered before (SV0) and after a treatment with albendazole (SVA) and clorsulon (SVC). Nested PCRs were carried out to amplify a fragment of 798 bp of the COX1 subunit and 870 bp of the NAD1 subunit. The pairwise sequence identity between eggs was analyzed for each strain. Population diversity indices, neutrality indices, and the degree of gene flow among the strains were evaluated. As a result, we have shown that there was homogeneity in the demographic expansion of the studied strains, and, according to the pairwise fixation index, these were not genetically differentiated. Although we found that the resistant strains had lower pairwise percentage similarities, higher haplotype diversity, and higher frequencies of specific SNPs, especially in the COX1 subunit, these differences were not very significant. Therefore, we conclude that the presence of adult flukes resistant to anthelmintics does not result in significant higher genetic diversity in the mtDNA of their eggs.

Characterization of Dicrocoelium dendriticum haplotypes from sheep and cattle in Iran based on the internal transcribed spacer 2 (ITS-2) and NADH dehydrogenase gene (nad1)

The present study assessed whether the genetic variation among different hosts (sheep and cattle) and geographical isolates (n= 28) of Dicrocoelium dendriticum from Iran is present based on mitochondrial (nad1) and ribosomal (ITS-2) DNA markers. Molecular analysis revealed the presence of at least ten and two distinct haplotypes in the NADH dehydrogenase gene (nad1) and internal transcribed spacer 2 (ITS-2), respectively. The nad1 and ITS-2 sequence data were deposited in GenBank under accession numbers, JX050110–134 and JQ966972–3. According to the results of our study, ND-D and ITS-A are established as being the predominant haplotypes of D. dendriticum in Iran. The Iranian isolates showed a higher intraspecific genetic diversity of 0–0.97% for nad1, compared to 0–0.42% for ITS-2. The alignment and comparison of nad1 and ITS-2 sequences revealed eight and one polymorphic sites, respectively. In the nad1 sequences, six were silent and two nucleotide substitutions were responsible for amino acid alterations. A phylogenetic analysis of the sequence data revealed that host associations and geographic location are not likely useful markers for D. dendriticum haplotype classification. Consequently, sequencing results obtained from the nad1 gene as a mitochondrial marker for the first time in this study would provide a valuable tool to analyse further molecular details of D. dendriticum worldwide.

Molecular, biochemical, and morphometric characterization of Fasciola species potentially causing zoonotic disease in Egypt

Fascioliasis is an important disease caused by Fasciola hepatica and Fasciola gigantica. The distributions of both species overlap in many areas of Asia and Africa including Egypt. Fifty adult Fasciola worms were collected from livers of cattle and sheep slaughtered in abattoirs, Cairo, Egypt. They were subjected to morphological and metric assessment of external features of fresh adults, morphological and metric assessment of internal anatomy of stained mounted worms, determination of electrophorezed bands of crude adult homogenates using SDS-PAGE, and molecular characterization of species-specific DNA segments using RFLP-PCR. It was found that the correlation between conventional morphology and its morphotype was statistically significant (P value = 0.00). Using SDS-PAGE, 13 bands were detected among both genotypes of Fasciola (35.7, 33.6, 32.4, 29.3, 27.5, 26, 24.4, 23, 21.45, 19, 16.75, 12.5, and 9.1 kDa).The most prevalent bands were that with a molecular weight of 29.3, 26, and 19 kDa. Bands detected were common for both species, but protein bands could not distinguish between F. hepatica and F. gigantica. The result of PCR for the amplification of the selected 28S rDNA fragment with the designed primer set yielded 618 bp long PCR products for F. hepatica and F. gigantica. Different band patterns generated after digestion of the 618 bp segment by the enzyme AvaII obtained with F. hepatica showed segments of the length 529, 62, 27 bp, while with F. gigantica 322, 269, 27 bp bands were obtained. Genotyping revealed no equivocal results. The conventional morphological parameters for species determination of Fasciola spp. endemic in Egypt were evaluated versus protein bands characterization and genotyping. It was concluded that conventional morphological and metric assessments were not useful for differentiation between F. gigantica and F. hepatica due to extensive overlap in the relative ranges. Similar conclusion was reached concerning protein band characterization where the patterns of protein banding were mostly similar. In contrast, genotyping using RFLP-PCR gave consistent results and clear differentiation between the two species. Considering the implications of proper speciation of endemic parasites on clinical evaluation, therapy, epidemiology, and control measures, speciation of parasites is currently revised on molecular basis. The presently used molecular tool is therefore recommended for further study to help draw a proper map for geographical distribution of Fasciola species.