Genetic diversity patterns of Haemonchus contortus isolated from sheep and goats in Bangladesh

An RPA-CRISPR/Cas12a-assisted method for nucleic acid detection of Haemonchus contortus in sheep

Haemonchus contortus (H. contortus), a highly pathogenic and blood-feeding nematode, could cause haemonchosis，resulting in tens of billions of dollars in production losses and significantly impacting the development of sheep husbandry. Rapid and accurate detection methods were particularly important for the prevention and control of haemonchosis. In this study, we developed a one-pot effective detection method that integrating recombinase polymerase amplification (RPA) with CRISPR/Cas12a technology based on the conserved region of ITS2 of H. contortus, with readout through fluorescence signals visualized by lateral flow strips (LFS) and observable under UV or blue light. The detection procedure was successfully finished in within 1 h and demonstrated high specificity and sensitivity, with no cross-reactivity detected with nine other common ovine pathogens and a detection limit as low as 0.1 copies/μL for fluorescence and 100 copies/μL for LFS. Validation with 89 sheep fecal samples revealed a 46.07 % positivity rate, fully consistent with quantitative PCR results. In summary, the RPA-CRISPR/Cas12a method for H. contortus detection exhibited the advantages of high specificity, high sensitivity, and low device dependence, portable and visible results. The technique presented significant potential for large-scale clinical application and provided novel point-of-care testing for clinical use in remote rural and resource-constrained areas.

Haemonchus contortus, an obligatory haematophagus worm infection in small ruminants: Population genetics and genetic diversity

Haemonchus contortus, a stomach worm, is prevalent in ruminants worldwide. They particularly hamper profitable small ruminant production. Here, we estimate the genetic variation of H. contortus collected from slaughtered goats and sheep from various geographic zones of Bangladesh using multiple genes. To perform this, adult parasites were isolated from the abomasum of slaughtered animals (sheep and goats). Among them, 79 male H. contortus were identified by microscopy. Following the extraction of DNA, ITS-2 and cox1 genes were amplified and subsequently considered for sequencing. After alignment and editing, sequences were analyzed to find out sequence variation, diversity pattern of genes, and population genetics of isolates. Among the sequence data, the analyses identified 19 genotypes of ITS-2 and 77 haplotypes of cox1 genes. The diversity of nucleotides was 0.0103 for ITS-2 and 0.029 for cox1 gene. The dendogram constructed by the genotype and haplotype sequences of H. contortus revealed that two populations were circulating in Bangladesh without any demarcation of host and geographic regions. Analysis of population genetics demonstrated a high flow of genes (89.2 %) within the population of the worm in Bangladesh. The Fst value showed very little amount of genetic difference among the worm populations of Bangladesh but marked genetic variation between different continents. The findings are expected to help explain the risks of anthelmintic resistance and the transmission pattern of the parasite, and also provide a control strategy against H. contortus.

Genetic diversity and haplotypes of Cysticercus tenuicollis isolates from slaughtered sheep and goats in Elazig and Bingol provinces of Turkey

BACKGROUND

The cestode Taenia hydatigena uses canids, primarily dogs, as definitive hosts, whereas the metacestode larval stage cysticercus infects a range of intermediate hosts, including domestic animals such as goats, sheep and pigs.

OBJECTIVES

In this study, we aimed to determine the genetic differences and haplotypes of Cysticercus tenuicollis isolates obtained from sheep and goats slaughtered in the Bingol and Elazig provinces of Turkey.

METHODS

C. tenuicollis isolates were collected from 44 sheep and 26 goats slaughtered in slaughterhouses in Bingol and Elazig. After the isolation of total genomic DNA from C. tenuicollis isolates, the genetic characterization of the partial mitochondrial cytochrome oxidase 1 (CO1) gene region (866 bp) was amplified using specific primers by polymerase chain reaction (PCR), the products were then sequenced, and haplotype and genetic diversity analyses were carried out.

RESULTS

As a result of the haplotype network analyses, 34 different haplotypes were detected around the main haplotype (Hap02) arranged in a star-like configuration and separated from other haplotypes by 1-28 mutation steps and covering 22.85% (16/70) of all isolates. Twenty-seven polymorphic fields were detected, 77.77% (21/27) of which were parsimony-informative, and secondary haplotype and nucleotide diversity were observed. Additionally, we detected high intraspecies haplotype diversity (hd: 0.933) and high nucleotide diversity (π: 0.00383), with 27 different nucleotide variation positions among the haplotypes of the isolates. Tajima's D value was negative, indicating population expansion and/or selection purification. The significantly negative Fu's Fs values indicated recent population expansion or the presence of expected rare haplotypes.

CONCLUSION

The results of this study confirmed that C. tenuicollis isolates clustered in one lineage and were closely related to the relevant reference sequences in different countries, confirming the circulation of C. tenuicollis in different geographical regions.

Comparison of the first time detected Oesophagostomum asperum with Oesophagostomum columbianum in sheep and goats in Bangladesh based on the trinity: Morphology, morphometry and genetic diversity

Oesophagostomum spp. (Family: Chabertiidae) is keeping a low profile in terms of severity in Bangladesh while maintaining economic loss through disguise within sheep and goats. The study was performed to identify prevalence, confirmation of species through morphology and morphometry followed by phylogeny using ITS2 and COX1 genes. In total 384 slaughterhouse-sourced small and large intestines were pooled from Mymensingh, Kishoreganj, Netrokona, Sherpur and Tangail districts of Mymensingh division. Followed by isolation, O. columbianum and O. asperum were identified following their key morphological features. Notably, O. asperum was first time detected in Bangladesh. The overall prevalence of Oesophagostomum spp. was found 60.93%. The prevalence of O. columbianum (64.95%) was almost double than that of O. asperum (35.04%). Among several characters, only the distance between anus to tail tip showed a significant morphological disparity in female. The Neighbor-joining (NJ) phylogenic trees based on ITS2 and COX1 genes confirmed the study species. The first time identified O. asperum along with morphometry and phylogeny will add value to the fact that nematodes are invisibly present with high prevalence in this country. This study will help to draw specific attention to command a practical control strategy for intervening in economic loss.

Epidemiology and phylogeny of Haemonchus contortus through internal transcribed spacer 2 gene in small ruminants

Introduction

Haemonchus contortus (H. contortus) is a blood-feeding nematode causing infectious disease haemonchosis in small ruminants of tropical and subtropical regions around the world. This study aimed to explore the prevalence and phylogeny of H. contortus in small ruminants using the internal transcribed spacer-2 (ITS-2) gene. In addition, a comprehensive review of the available literature on the status of H. contortus in Pakistan was conducted.

Methods

Fecal samples were collected from sheep and goats (n = 180). Microscopically positive samples were subjected to DNA extraction followed by PCR using species-specific primers.

Results

The overall prevalence of H. contortus was 25.55% in small ruminants. The prevalence of H. contortus was significantly associated with months and area. The highest occurrence of haemonchosis was documented in July (38.70%), whereas the lowest occurred in December (11.11%), with significant difference. The prevalence was highest in the Ghamkol camp (29.4%) and lowest in the arid zone of the Small Ruminant Research Institute (17.5%) (p = 0.01). The results of the systematic review revealed the highest prevalence of haemonchosis (34.4%) in Khyber Pakhtunkhwa (p = 0.001).

Discussion

Phylogenetic analysis revealed a close relationship between H. contortus and isolates from Asia (China, India, Iran, Bangladesh, Malaysia, and Mongolia) and European countries (Italy and the United Kingdom). It has been concluded that H. contortus is prevalent in small ruminants of Kohat district and all over Pakistan, which could be a potential threat to food-producing animals, farmers, dairy, and the meat industry. Phylogenetic analysis indicates that H. contortus isolates share close phylogenetic relationships with species from Asia and Europe.

Extensive Countrywide Molecular Identification and High Genetic Diversity of Haemonchus spp. in Domestic Ruminants in Greece

The gastrointestinal nematode parasite Haemonchus spp. is one of the most pathogenic parasites of ruminants, due to its blood-sucking activity, which causes large economic losses in the ruminant industry. The latest epizootiological data recorded an increase in the infection, not only in Greece but also in other countries, mainly attributed to climatic changes. The study of the population structure and the investigation of the phylogenetic relationships of Haemonchus spp. are essential for the understanding of its biology and epizootiology to implement appropriate control and prevention strategies. In addition, the molecular approach allows the determination of evolutionary relationships between different species of this parasite, the diverse hosts they infect, as well as the different geographic compartments from which they originate. Therefore, the aim of the present study was to identify the species of the sympatric populations of the genus Haemonchus, a nematode parasite infecting ruminants (sheep, goats, cattle, and buffaloes) from different regions of Greece (continental and insular) using molecular methods. At the same time, an attempt was made to identify the possible subpopulations of Haemonchus spp. in Greece, to investigate their phylogenetic relationships, as well as to determine the genetic diversity of each population. A total of 288 worms of the genus Haemonchus were processed using molecular methods; of these, 96 were collected from sheep, 96 from goats, 48 from cattle, and finally, 48 from buffaloes. A fragment of 321 base pairs of the second internal transcribed spacer (ITS2) sequence of nuclear DNA was amplified for species identification, and, after basic local alignment search tool (Blast) analysis, it was revealed that they belonged to H. contortus. A fragment of 820 base pairs of subunit 4 of the nicotinamide dehydrogenase (ND4) gene of mitochondrial DNA was amplified for genetic diversity analysis. The Greek mitochondrial ND4 sequences of H. contortus were classified into 140 haplotypes, and the values of the average nucleotide and haplotype diversity were lower compared to the respective values derived from Italy, Malaysia, the USA, and China. The phylogenetic analysis of the ND4 gene revealed a clear grouping of the Greek haplotypes when compared with Asian ones, and, at the same time, there was no profound grouping of the same haplotypes with regard to their different hosts and geographical origin within different regions of Greece. The aforementioned findings confirmed that H. contortus prevails in our country and can infect all species of ruminants, without geographical boundaries, when the right conditions (i.e., common grazing) are created.

Characterization and population genetics of Haemonchus contortus in Merino sheep in Lesotho

Haemonchus contortus is the most pathogenic and economically restrictive gastrointestinal nematode in the small ruminant industry globally. Morbidity, poor cross-bodily state, and mortality of sheep in Lesotho suggest the presence of H. contortus. The present study investigated the morphological, molecular, and population genetics of H. contortus third-stage larvae infecting sheep in four ecological zones (EZ) of Lesotho. Coprocultures were prepared for larval morphological identification and PCR determination. Larvae were identified morphologically as 100% H. contortus. The Second Internal Transcribed Spacer (ITS-2) gene of the ribosomal DNA of H. contortus isolates in the present study revealed nucleotide homology ranging from 97 to 100% when compared with selected GenBank reference sequences. Pairwise evolutionary divergence among H. contortus isolates was low, with 0.01318 recorded as the highest in the present study. Five haplotypes resulted from 14 Lesotho sequences. Haplotype diversity and nucleotide diversity were 0.76923 and 0.00590, respectively. Genetic differentiation among isolates was low but not statistically significant. An analysis of molecular variance revealed that most molecular variation was distributed within topographic populations at 94.79% (FST = 0.05206, p > 0.05) and 5.21% among populations. There was high gene flow and no definite population genetic structure among Lesotho isolates.

Morphological and phylogenetic analysis of Raillietina spp. indigenous chickens (Gallus gallus domesticus) in Bangladesh

Raillietina spp. (Cestoda: Davaineidae), the most common cestodes in indigenous chickens, cause a substantial production loss in poultry industry in Bangladesh. Here, we estimated the prevalence, confirmed the species and determined the genetic pattern of species of Raillietina using molecular tools. We collected and examined 375 chickens randomly from household of different villages of Mymensingh sadar and Gouripur upazila, Mymensingh district and adult parasites were isolated and identified. Genomic DNA was extracted from collected parasites, amplified ITS-2 and ND-1 genes, sequenced and analyzed. Out of 375 samples, 270 (72.0%) were found positive with Raillietina species and mean worm burden was 10.46 ± 0.56. Microscopically, three species of Raillietina, such as R. cesticillus (37.9%), R. echinobothrida (41.1%) and R. tetragona (52.8%) were detected on the basis of their morphological features. The total length, length and width of scolex, sucker and rostellum were also measured. Among different factors, age, farming nature and flock size of chickens were significantly (p < 0.05) influenced Raillietina infections. For further validation, the sequences of ITS-2 gene generated in this study were matched with reference sequences of R. cesticillus, R. echinobothrida and R. tetragona and found 99.63% - 100% similarity. The phylogenetic analyses of ITS-2 and ND-1 sequences were clustered together with the reference sequences of R. cesticillus, R. echinobothrida and R. tetragona confirming microscopic identification. This is the first confirmation of species of Raillietina along with the prevalence of the species, which will be helpful for the formulation of a control strategy and provide basic information for further molecular study.

Morphometry and genetic diversity pattern of Cysticercus tenuicollis, an important food-borne taeniid metacestode in goats in Bangladesh

Cysticercus tenuicollis is a larval stage of Taenia hydatigena resulting in cysticercosis, and responsible for enormous economic loses, especially in livestock production. Here, we planned to determine the prevalence and explore genetic variation of C. tenuicollis isolated from goats based on small subunit ribosomal RNA (rrnS) and cytochrome oxidase subunit 1 (cox1). To do this, samples were collected from different slaughter houses of municipal areas such as Bramhapalli slaughterhouse, Jubileeghat slaughterhouse and Mesuabazar slaughterhouse at Mymensingh sadar, and tentatively identified by morphological and morphometrical analysis. To study genetic variation, DNA was extracted from C. tenuicollis, and amplified rrnS and cox1 genes using specific primers, and were sequenced. Among 1372 examined animals, 177 (12.9%) were infected with C. tenuicollis. Cysts were recovered from peritoneum (7.9%), liver (4.4%) and urinary bladder (0.6%) of the infected animals. Females (18.9%) and adults (20.7%) were significantly more susceptible than male (8.8%) and young (9.3%), respectively. Genetic analysis defined 8 distinct rrnS genotypes and 9 unique cox1 haplotypes among 20 C. tenuicollis isolates. The nucleotide diversities were 0.00283 and 0.00434 for rrnS and cox1 genes, respectively. Neighbor joining (NJ) trees of rrnS and cox1 gene were constructed and the studied sequences were clustered with reference sequences of T. hydatigena with strong nodal support (100%). To compare Bangladeshi isolates, a median joining network was constructed with the population from other geographical regions and hosts. This led to a clustering pattern, but the clusters were not built with unique geographical regions or hosts. In conclusion, this is the first study that describes the genetic variation of T. hydatigena population and suggests the existence of host-specific variants. Therefore, it is fundamental to dispose infected viscera, restrict dog movement and proper management of slaughter house for the prevention and control of cysticercosis.

Population genetic structure and morphological diversity of Cruzia tentaculata (Nematoda: Ascaridida), a parasite of marsupials (Didelphinae), along the Atlantic Forest on the eastern coast of South America

Cruzia tentaculata is a helminth parasite of marsupials and has a wide geographic distribution from Mexico to Argentina. The aim of this study was to analyse the genetic population structure of this nematode along the Atlantic Forest biome. Cruzia tentaculata specimens were recovered from Didelphis aurita, Didelphis albiventris and Philander quica in 9 localities. Morphological and morphometric data were investigated for phenotypic diversity among localities and hosts using multivariate discriminant analysis of principal components. Phylogenetic relationships of C. tentaculata were determined using maximum likelihood and Bayesian inference. The population structure was analysed by fixation indices, molecular variance analysis, Tajima's D and Fu's Fs neutrality tests, Mantel tests and Bayesian clustering analysis. A higher significant morphometric difference for males was observed between localities. In the haplogroup networks, 2 groups were recovered, separating locations from the north and from the south/southeast. The morphometric variation in C. tentaculata between different localities was compatible with this north and southeast/south pattern, suggesting adaptation to different ecological conditions. Population genetic analyses suggested a pattern of evolutionary processes driven by Pleistocene glacial refugia in the northeast and southeast of the Atlantic Forest based on the distribution of genetic diversity.

Selection of genome-wide SNPs for pooled allelotyping assays useful for population monitoring

Parasitic worms are serious pests of humans, livestock and crops worldwide. Multiple management strategies are employed in order to reduce their impact, and some of these may affect their genome and population allelic frequency distribution. The evolution of chemical resistance, ecological changes, and pest dispersal have allowed an increasing number of pests to become difficult to control with current management methods. Their lifestyle limits the use of ecological and individual-based management of populations. There is a need to develop rapid, affordable, and simple diagnostics to assess the efficacy of management strategies and delay the evolution of resistance to these strategies. This study presents a multi-locus, equal-representation, whole genome pooled SNPs selection approach as a monitoring tool for the ovine nematode parasite Haemonchus contortus. The SNP selection method used two reference genomes of different quality, then validated these SNPs against a high-quality recent genome assembly. From over 11 million high-quality SNPs identified, 334 SNPs were selected, of which 262 were species-specific, yielded similar allele frequencies when assessed as multiple individuals or as pools of individuals, and suitable to distinguish mixed nematode isolate pools from single isolate pools. As a proof-of-concept, 21 Australian H. contortus populations with various phenotypes and genotypes were screened. This analysis confirmed the overall low-level of genetic differentiation between populations collected from the field, but clearly identifying highly inbred populations, and populations showing genetic signatures associated with chemical resistance. The analysis showed that 66% of the SNPs were necessary for stability in assessing population genetic patterns, and SNP pairs did not show linkage according to allelic frequencies across the 21 populations. This method demonstrates that ongoing monitoring of parasite allelic frequencies and genetic changes can be achieved as a management assessment tool to identify drug-treatment failure, population incursions, and inbreeding signatures due to selection. The SNP selection method could also be applied to other parasite species.

Genetic diversity and population structure of Haemonchus contortus in goats from Thailand

Haemonchus contortus is one of the most economically important parasitic nematodes affecting small ruminant livestock worldwide. This study was conducted to elucidate the genetic diversity and population structure of this nematode in Thailand based on mitochondrial DNA markers, the nicotinamide dehydrogenase subunit 4 (nad4) and the cytochrome c oxidase subunit 1 (cox1) genes. One hundred and thirty-six adult worms were obtained from 86 abomasa of slaughtered goats from 13 different localities in 5 regions of Thailand. Identification to the genus Haemonchus was done using morphology. DNA sequences of the nuclear ribosomal second internal transcribed spacer (ITS2) identified each specimen to species: three fixed nucleotide (SNP) differences distinguished H. contortus from H. placei. Genetic analysis defined 118 and 122 unique haplotypes in partial sequences of nad4 (alignment length 723 bp) and cox1 (645 bp) genes, respectively. Nucleotide diversities were 0.031 and 0.043 for nad4 and cox1 genes, respectively. Low genetic differentiation was observed among H. contortus samples from various provinces in Thailand. This is the first study on the genetic diversity and population structure of H. contortus of goats in Thailand. This study has provided insights into the transmission dynamics of this parasitic nematode, information which is essential for farm management and parasite control.

Morphometrical and Molecular Characterization of Oesophagostomum columbianum (Chabertiidae: Oesophagostominae) and Haemonchus contortus (Trichostrongylidae: Haemonchinae) Isolated from Goat (Capra hircus) in Sylhet, Bangladesh

This study was aimed at describing two (2) intestinal nematodes from naturally infected native breed of goats (Capra hircus) in Bangladesh, identified as Oesophagostomum columbianum (Curtice, 1890) Stossich 1899 and Haemonchus contortus (Rudolphi, 1803) Cobb, 1898. The identification was made based on morphometric features and was confirmed by amplifying internal transcribed spacer (ITS) and cytochrome c oxidase (cox1) gene. Well-developed lateral alae, distinct cervical papillae anteriorly to esophageal expansion, and male spicule length (0.73-0.79 mm, n = 2) were characteristically observed in O. columbianum. At the same time, male spicule length (0.40-0.46 mm, n = 2) and position of female vulvar flap (4.30-4.54 mm from posterior end, n = 3) were observed in H. contortus. DNA sequence homology of the ITS and cox1 gene of both specimens revealed the same results, showing similarity to the GenBank sequences of O. columbianum (GenBank No. KC715827; JX188470) and H. contortus (GenBank No. KJ724377; HQ389229). Phylogenetic analysis computed by maximum livelihood (ML) from the ITS nucleotide sequences revealed that the O. columbianum and H. contortus isolates identified in this study were clustered in the same clade with isolates from China and Iran, respectively. This study, for the first time, illustrates the characteristics of O. columbianum and H. contortus in Bangladesh, combining both morphological and molecular data. The universal primer-based polymerase chain reaction (PCR) protocol could be an economical and efficient option for researchers from poor resource settings for precise identification of nematodes. The information generated in this study may contribute to formulating effective control strategies against these nematodes.

Nemabiome metabarcoding reveals differences between gastrointestinal nematode species infecting co-grazed sheep and goats

Our current understanding of differences in the epidemiology of gastrointestinal nematode (GIN) species in co-grazed sheep and goats is inadequate with reference to the development of sustainable control strategies. The next-generation metabarcoding sequencing method referred to as the 'nemabiome' allows some of these differences to be explored to describe the intensity of co-infecting GIN species. We applied this platform to study sheep and goats that were co-grazed on Guinea grass pasture in northeastern Brazil. Co-grazed goats and sheep were treated with a monepantel anthelmintic, then exposed to the same gastrointestinal nematode species. Overall, there were differences in the prevalence of GIN species identified in the sheep and goats; Trichostrongylus colubriformis and Teladorsagia circumcincta predominated in goat kids, while Haemonchus contortus predominated in adult does, ewes and lambs once burdens became re-established after anthelmintic treatment. Description of the pattern of re-infection following anthelmintic treatment was prevented by the unpredicted poor efficacy of 2.5 mg/kg and 5 mg/kg, respectively, of monepantel against O. columbianum and T. circumcincta in lambs, and T. circumcincta adult does. Differences in drug efficacy between host age and species groups may be important when considering sustainable GIN control strategies for co-grazed animals. The aggregated FECs of the adult does and goat kids representing re-established GIN burdens, were higher than those of the co-grazed adult ewes and lambs. This implies that there are inherent differences in GIN species adaptation to the two naïve small ruminant host species, and shows the need for better understanding of the factors giving rise to this situation associated with exposure to infective larvae and host responses. At the start of the study, the adult does were co-infected with several GIN species, with the highest intensity of T. circumcincta, contrasting with the situation in the adult ewes, in which H. contortus predominated. However, once burdens became re-established after treatment, H. contortus predominated in both adult does and ewes. This demonstrates the potential for host burdens of H. contortus to establish and predominate after anthelmintic treatment when burdens of co-infecting GIN species are low.

Assessment of in vitro anthelmintic activity and bio-guided chemical analysis of BRS Boyrá pineapple leaf extracts

Species of the Bromeliaceae are known for their pharmacological actions, including anthelmintic effects. The aim of this study was to investigate the in vitro anthelmintic activity of extracts and fractions of BRS Boyrá pineapple leaf against the eggs and infective larvae of gastrointestinal nematodes (Trichostrongylidae) of goats and to identify the compounds involved in this activity. Crude methanol, hexane, dichloromethane, ethyl acetate and residual hydromethanol extracts were investigated by quantitative analysis of phenolic and flavonoid contents, antioxidant activity, anthelmintic activity against gastrointestinal nematodes of goats. The extracts were submitted to chromatographic methods for substance isolation and spectrometric techniques to identify their structures. The anthelmintic activity was performed by in vitro assays with eggs and larvae of nematodes obtained from naturally infected donor goats. All extracts contained phenolic (2.22-14.12 g of gallic acid equivalent per 100 g of dry extract) and flavonoid compounds (0.13-1.45 g of quercetin equivalent per 100 g of dry extract). Bio-guided fractionation of the BRS Boyrá pineapple leaves showed high antioxidant activity (EC₅₀ for DPPH of 2.16-21.38 mg mL^-1 and inhibition of co-oxidation of β-carotene of 36.40-74.86%) and anthelmintic activity (15.69-100% inhibition of egg hatching). The ethyl acetate extract exhibited greatest activity in all assays. Through chromatographic column analysis it was possible to isolate three substances: β-sitosterol and stigmasterol mixture in dichloromethane and hexane extracts, identified by NMR and p-coumaric acid in the ethyl acetate extract, identified by HPLC-DAD. The isolated p-coumaric acid exhibited high ovicidal effect against goat gastrointestinal nematodes (IC₅₀: 0.12 mg mL^-1) and can be considered the active substance of the ethyl acetate extract. This study revealed for the first time that the pineapple BRS Boyrá possesses inhibitory activity against gastrointestinal nematodes (Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp.), and that p-coumaric acid is an important bioactive.

Haemonchus contortus: siRNA mediated knockdown of matrix metalloproteinase 12A (MMP-12) results in reduction of infectivity

BACKGROUND

RNA interference (RNAi) is an important tool to determine the role of genes. RNAi has been widely used to downregulate target molecules, resulting in the reduction of mRNA for protein expression. Matrix metalloprotease 12A (MMP-12) is known to have important roles during embryonic development, organ morphogenesis and pathological processes in animals. However, MMP-12 from Haemonchus contortus has not been characterized.

METHODS

Haemonchus contortus MMP-12 gene was cloned and recombinant protein of MMP-12 (rHc-MMP-12) was expressed. Binding activities of rHc-MMP-12 to goat peripheral blood mononuclear cells (PBMCs) were assessed by immunofluorescence assay (IFA) and the immuno-regulatory effects of rHc-MMP-12 on cell proliferation and nitric oxide production were observed by co-incubation of rHc-MMP-12 with goat PBMCs. Furthermore, a soaking method was used to knockdown the expression of Hc-MMP12 gene using three siRNA, targeting different regions of the gene and infectivity of effective siRNA on the development of H. contortus was evaluated in goat.

RESULTS

rHc-MMP-12 was successfully expressed in an expression vector as well as the tissues of the cuticle of adult H. contortus worms and a successful binding with PBMCs surface were observed. Increased cellular proliferation and nitric oxide production by goat PBMCs was observed in a dose-dependent manner. Quantitative real time PCR (qRT-PCR) results confirmed the successful silencing of Hc-MMP-12 gene in siRNA of 1, 2 and 3 treated third-stage larvae (L3) of H. contortus in vitro. The most efficient qRT-PCR-identified siRNA template was siRNA-2, with a 69% suppression rate compared to the control groups. Moreover, in an in vivo study, silencing of the Hc-MMP-12 gene by siRNA-2 reduced the number of eggs (54.02%), hatchability (16.84%) and worm burden (51.47%) as compared to snRNA-treated control group. In addition, a shorter length of worms in siRNA-2-treated group was observed as compared to control groups.

CONCLUSIONS

Our results indicate that siRNA-mediated silencing of Hc-MMP-12 gene in H. contortus significantly reduce the egg counts, larval hatchability, and adult worm counts and sizes. The findings of the present study demonstrate important roles of Hc-MMP-12 in the development of H. contortus.

Multiple anthelmintic resistance in gastrointestinal nematodes of small ruminants in Bangladesh

Anthelmintic resistance (AR) against gastrointestinal nematodes (GINs) of sheep and goats is a global concern. To address the problem, this study assessed the status of AR in different government and private sheep and goat farms in Bangladesh. We conducted fecal egg count reduction test (FECRT) and Egg hatch assay (EHA) experiments. For the detection of resistant larvae, pooled fecal samples from treated and non-treated groups were subjected to coproculture. Furthermore, 195 adult Haemonchus parasites were genotyped to ascertain benzimidazole (BZ) resistance allele from seven topographic zones of Bangladesh using allele specific PCR (AS-PCR). In FECRT, the percentage reduction along with 95% confidence intervals indicated that GINs were resistant to albendazole (ABZ), levamisole (LEV) and ivermectin (IVM). Coproculture revealed that Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp. were resistant to anthelmintics. ABZ resistance was also confirmed by in vitro EHA in all the farms except the private goat farm in Mymensingh. The genotype frequencies were 6% for homozygous resistant (rr), 59% for heterozygous (rS) and 35% for homozygous susceptible (SS) among different topographic zones. The allelic frequency of the mutation conferring resistance (r) ranged from 25% to 47% signifying resistance to BZ in nematodes of sheep/goats. The genotype frequencies (rr, rS and SS) and allelic frequencies (r and S) varied significantly (p˂0.05) in different zones in Bangladesh. Overall, the data suggest an alarming condition created by multiple AR in Bangladesh.

Galectin Domain Containing Protein from Haemonchus contortus Modulates the Immune Functions of Goat PBMCs and Regulates CD4+ T-Helper Cells In Vitro

Galectins are glycan-binding proteins that are widely expressed and distributed in mammalian tissues as well as cells of innate and adaptive immune responses. CD4+ T-helper cells differentiate into effector subsets in response to cytokines. T helper 9 cells are one of the recently described subsets of effector T cells that are relatively new and less studied. In this study, galectin domain containing protein from Haemonchus contortus (Hc-GDC) was cloned, expressed in pET32a, and immunoblotting was performed. Localization of recombinant (r)Hc-GDC on outer and inner surface of H. contortus worm and binding with goat Peripheral Blood Mononuclear cells (PBMCs) were performed using immunofluorescence assay. Moreover, effects of rHc-GDC on proliferation, apoptosis, cell migration, and the nitric oxide production in goat PBMCs were evaluated. Furthermore, modulatory effects of rHc-GDC on production of Th1, Th2, and Th9 cells were evaluated by flowcytometry and on interferon gamma, interleukin (IL)-4 and IL-9 were evaluated by quantitative real-time polymerase chain reaction. The results demonstrated that rHc-GDC was successfully cloned, expressed in expression vector as well as in the gut surface of adult H. contortus worm and successful binding with PBMCs surface were observed. Immunoblotting results revealed that rHc-GDC is an important active protein of H. contortus excretory and secretory products. Moreover, the interaction of rHc-GDC with host cells increased the production of Th2, Th9 cells, IL4, IL-9, PBMC proliferation, nitric oxide, and cell migration. No effects of rHc-GDC were observed on PMBC apoptosis, production of Th1 cells, and secretions of IFN- and IL-10 cytokines. These findings indicate that recombinant GDC protein from H. contortus modulates the immune functions of goat PBMCs and has the potential to enhance protective immunity by inducing T helper-9-derived IL-9 in vitro.

Development and field evaluation of a species-specific mt-COI targeted SYBR-Green Real Time PCR for detection and quantification of Haemonchus contortus in cattle in Turkey

Haemonchus contortus is one of the most important gastrointestinal nematodes (GINs) infecting sheep, goats, and cattle worldwide. We developed a SYBR Green real-time PCR (qPCR) assay for detection and quantification of H. contortus by using specific primers based on a conserved region of the mitochondrial cytochrome oxidase subunit I (mt-COI) gene, and evaluated this technique in the detection of H. contortus infections in cattle in Central Anatolia Region of Turkey. The newly developed qPCR assay successfully discriminated H. contortus from other GIN species infecting cattle in the specificity evaluations, with a specific melt peak of 77.5 °C. Our results revealed the efficient amplification of the proposed target COI region within the range of plasmid copies, from 2 × 10⁶ to 2 × 10¹ per μl, with 96.9 % efficiency, R² value of 0.999, and a slope of -3.398. Among the 920 cattle fecal samples from the field, 58 samples (6.3 %) were positive with qPCR assay, whereas 45 samples (4.9 %) were positive, as determined by larval culture, suggesting the utility of SYBR Green qPCR. Phylogenetic characterization of the partial COI gene of H. contortus isolates was also evaluated for 100 eggs and third stage larvae recovered from positive cattle faecal samples, which were verified with the qPCR assay prior to analyses. COI sequences were classified into three haplotypes (THC1 to THC3) with intraspecific nucleotide differences of 0.50 to 0.76 %. Phylogenetic analyses revealed that the haplotypes grouped with H. contortus isolates from several countries in a monophyletic cluster, with evidence of at least two main haplogroups. Overall, the SYBR Green qPCR assay was highly specific and sensitive, suggesting that it can be used for screening of H. contortus infections in livestock populations in epidemiological studies and the control of this important parasite.

Immunodiagnostic potential of recombinant tropomyosin during prepatent Haemonchus contortus infection in goat

Excretory and secretory products (ESPs) are released by the parasites during Haemonchus contortus (H. contortus) infection. In this study, Tropomyosin (TpMy), one of these ESPs was used to develop western blotting and optimized Enzyme Linked immunosorbent assay (ELISA) for detection of H. contortus during early infection in goat. Microscopic examination was performed parallel for comparison. Recombinant tropomyosin protein was purified successfully. Western blotting results revealed that anti-recombinant H. contortus Tropomyosin (rHc-TpMy) antibodies could recognize the natural proteinand rHc-TpMy antigen did not show any cross-reaction with goat anti-sera of Fasciola hepatica, Trichinella spiralis, and Toxoplasma gondii. Moreover, initial antibodies were detected by both western blotting and indirect ELISA at 14 days post infection (DPI) and persisted till 30 DPI but fecal eggs count couldn't detect the eggs in feces at early stage (7 and 14 DPI). The optimized antigen coating concentration was calculated as 10 μg/ml (P/N Optimum Density₄₅₀ = 4.165) with optimized dilution of serum (1:50) and secondary antibody (1:2500). Positive and negative cutoff value of the indirect-ELISA assay was calculated as 0.392 and 0.344, respectively. Receiver operating characteristic curve analysis validated the cutoff value (0.392) based on a high specificity and sensitivity. Indirect ELISA showed 90% diagnostic sensitivity and 100% diagnostic specificity. In comparison of serological and conventional method, rHc-TpMy based indirect ELISA showed more positive results (30%; 9/30) than microscopic examination (20%; 6/30). These results demonstrated that rHc-TpMy is a potential immunodiagnostic antigen to detect specific antibodies at early stage of infection in goat and serological methods are more reliable as compared to microscopic examination.