High-resolution melting analysis (HRM) for differentiation of four major Taeniidae species in dogs Taenia hydatigena, Taenia multiceps, Taenia ovis, and Echinococcus granulosus sensu stricto

Development of a Multiplex High-Throughput Diagnostic Assay for the Detection of Strawberry Crown Rot Diseases Using High-Resolution Melting Analysis

Rapid and accurate disease diagnosis is a prerequisite for an effective disease management program in strawberry production. In Florida, Colletotrichum spp., Phytophthora spp., and Macrophomina phaseolina are the primary microorganisms causing strawberry crown rot. Even though the diseases can be caused by different pathogens, symptoms are indistinguishable and equally devastating. To inform strawberry growers in a timely fashion of diagnostic results for effective deployment of chemical control practices, we developed a multiplex high-resolution melting (HRM) assay to rapidly and accurately detect the abovementioned pathogens. The multiplex HRM assays using three predesigned primer pairs showed high specificity for individual species by generating specific melting peaks without cross-reaction between primers or with other common strawberry pathogens. The amplification limit of the assay was 1 pg of Colletotrichum and Phytophthora and 100 pg of M. phaseolina DNA per 10-μl reaction. However, the presence of different melting peaks was observed in mixed DNA samples and was concentration and target DNA dependent. A crude DNA extraction protocol was developed to allow high-throughput screening by minimizing the inhibitory effects. Moreover, we applied the HRM assay to 522 plant samples and found high correlations between conventional pathogen isolation and HRM and between singleplex and multiplex assays. Altogether, this multiplex HRM assay is specific, cost effective, and reliable for the timely detection of strawberry crown rot pathogens.

Rapid Identification of Tropilaelaps Mite (Mesostigmata: Laelapidae) Species Using a COI Barcode-HRM

Tropilaelaps mite (Mesostigmata: Laelapidae) is an ectoparasite of bees present, to date, only on the Asian continent. In the context of the threat of Tropilaelaps's introduction into new regions, accurate, rapid, and sensitive detection of the Tropilaelaps spp. is essential. In the present study, we developed a novel molecular method for bee mite's identification, which consists of a new real-time PCR method. A high-resolution melting analysis (HRM) was then performed on the amplified products to differentiate the species. PCR amplification was applied on the cytochrome c oxidase subunit I gene (580 bp). Short fragments from the most variable regions of this gene were identified in silico to amplify and discriminate among the four Tropilaelaps species. Four reference plasmids were synthesized to characterize species by well-distinguished melting curves. The method was then validated in terms of its specificity and sensitivity using a panel of 12 specimens. The results showed that an HRM method can be applied for the intended objective: for rapid and simultaneous identification of Tropilaelaps species. To our knowledge, this study reports the first direct HRM assay developed for the genome of a bee mite, specific for Tropilaelaps species. This COI barcode-HRM technique could be a promising tool for mite species identification.

Taeniid cestodes in a wolf pack living in a highly anthropic hilly agro-ecosystem

The Italian wolf population in human-modified landscapes has increased greatly in the last few decades. Anthropisation increases the risk of transmission of many zoonotic infections and in this context, control of taeniid cestode species needs to be addressed from a One Health perspective. Predator-prey interactions are at the root of taeniid cestode transmission, and the wolf plays a key role in the maintenance and transmission of taeniids. To date, all available data on the taeniids of wolves in Italy refer to populations living in a wild habitat. Between 2018 and 2019, we investigated taeniids in a wolf pack living in a highly anthropic hilly agro-ecosystem. Thirty-eight faecal samples were collected and analysed, 4 of which were also genetically characterised for individual wolves and belonged to three different animals. Samples collected were analysed microscopically and by molecular analysis in order to identify the taeniid species. Taeniid eggs were detected in 34.2% (13/38) of samples. Within samples positive to taeniid eggs only Echinococcus granulosus s.s. and Taenia hydatigena were identified in 26.3% and 10.5% of the samples, respectively. On microscopic examination, Capillaria spp., Ancylostomatidae and Toxocara canis eggs, Crenosoma vulpis larvae, and coccidian oocysts were also found. The combination of low biodiversity of taeniid species with a high occurrence of E. granulosus s.s. recorded in this study could be the consequence of a deeper link occurring between wolves and livestock in human-modified landscapes than in wild settings.

Epidemiological and molecular studies on Echinococcus granulosus from free-roaming dogs in Southeast Iran

Background and Aim:

Cystic echinococcosis (CE), as a major zoonotic helminth infection, imposes remarkable socioeconomic burden on many endemic countries across the world, including Iran. Due to the high importance of free-roaming dogs in the transmission of CE, epidemiological and molecular studies in this type of hosts are required in the endemic regions. This study aimed to investigate the epidemiology and genotyping of Echinococcusgranulosus isolated from stray dogs in Kerman, Southeast Iran.

Materials and Methods:

Eighty-four samples were isolated from stray dogs in the city and suburbs of Kerman in coordination with the health authorities and the municipality office for rabies control and dog population management. Dog demographic data, including age and sex were collected. The worm was isolated by necropsy and genomic DNA was extracted and partial cytochrome c oxidase subunit 1 gene was amplified using specific primers. Phylogenetic and Templeton-Crandall-Sing (TCS) network analyses were carried out on the sequence data.

Results:

The overall prevalence of CE in the surveyed dogs was 10.7% (9/84 cases). Out of 84 stray dogs, 33 (39.3%) and 51 (60.7%) cases were male and female, respectively. There was not a statistically significant difference between the infection and gender of dogs. However, infection is shown more in dogs under one year of age with a statistically significant difference (p<0.05). The results of molecular studies indicated E. granulosus G1 genotype for all isolates. The high presence of free-roaming dogs in urban and peri-urban areas and high frequency of parasite in this animal is a risk factor for humans in the region. Haplotype sequence analysis on the dog isolates revealed a close relationship with other E. granulosus isolates in Kerman.

Conclusion:

The findings of this study provide evidence-based data about the epidemiological and molecular characteristics of CE in dog definitive hosts of Southeast Iran. Further studies are required to understand the prevalence and parasite genotypes in dogs in Iran.

Isolated Human and Livestock Echinococcus granulosus Genotypes Using Real-Time PCR of cox1 Gene in Northeast Iran

PURPOSE

Cystic echinococcosis (CE), caused by the metacestode of Echinococcus granulosus, is highly endemic over large parts of Iran. The purpose of this study was to investigate the prevalence rate of hydatidosis and mitochondrial cox1 real-time PCR with high-resolution melting curve (HRM) analysis of E. granulosus isolated from human and livestock.

METHODS

In this cross-sectional study, 61 formalin-fixed paraffin-embedded tissue isolates were collected from human CE cases and 83 hydatid cysts from the liver and lung lesions of the livestock in Khorasan Razavi province, Northeast Iran. DNA was extracted from each isolate and amplified by real-time PCR and analyzed using the HRM method.

RESULTS

The HRM analysis using the cox1 gene of 40 E. granulosus human isolates showed that 35 (87.5%), 4 (10%), and 1 (2.5%) of the isolates were categorized as G1, G3, and G6 genotypes, respectively. Out of the total 1342 livestock inspected, 39 (4%) goats and 44(12%) cattle were found harboring hydatid cysts all belonging to E. granulosus sensu stricto.

CONCLUSION

The results confirmed that the high prevalence of E. granulosus sensu stricto in intermediate hosts is remarkable in northeast of Iran coupled with the high prevalence of infection in livestock, which reinforced the need for hydatidosis control programs in this region.

Expression and serodiagnostic potential of antigen B and thioredoxin peroxidase from Taenia multiceps

Coenurosis is a serious parasitic disease of herbivorous animals caused by the metacestode of Taenia multiceps (Coenurus cerebralis). Accordingly, a significant amount of research is currently dedicated to the development of appropriate antigens for use in rapid and accurate coenurosis diagnosis kits. In the present study, antigen B (AgB) and thioredoxin peroxidase (TPx) from T. multiceps were cloned and expressed using a prokaryotic system, molecular characterization of Tm-AgB was determined by bioinformatical analyses. The serological diagnostic potentials of rTm-AgB and rTm-TPx were evaluated by indirect ELISA and compared with those of previously reported rTm-AnxB2, rTm-HSP70, and rTm-GST. The results showed that Tm-AgB is a specific lipoprotein of cestodes with good thermal stability. The ELISA assay showed that rTm-AgB exhibited a sensitivity of 95.8% and a specificity of 87.5%, indicating its strong potential for serological diagnosis of T. multiceps.

Is species identification of Echinostoma revolutum using mitochondrial DNA barcoding feasible with high-resolution melting analysis?

The taxonomic evaluation of Echinostoma species is controversial. Echinostoma species are recognized as complex, leading to problems associated with accurate identification of these species. The aim of this study was to test the feasibility of using DNA barcoding of cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 1 (ND1) conjugated with high-resolution melting (HRM) analysis to identify Echinostoma revolutum. HRM using COI and ND1 was unable to differentiate between species in the "revolutum complex" but did distinguish between two isolates of 37-collar-spined echinostome species, including E. revolutum (Asian lineage) and Echinostoma sp. A from different genera, e.g., Hypoderaeum conoideum, Haplorchoides mehrai, Fasciola gigantica, and Thapariella anastomusa, based on the T_m values derived from HRM analysis. Through phylogenetic analysis, a new clade of the cryptic species known as Echinostoma sp. A was identified. In addition, we found that the E. revolutum clade of ND1 phylogeny obtained from the Thailand strain was from a different lineage than the Eurasian lineage. These findings reveal the complexity of the clade, which is composed of 37-collar-spined echinostome species found in Southeast Asia. Taken together, the systematic aspects of the complex revolutum group are in need of extensive investigation by integrating morphological, biological, and molecular features in order to clarify them, particularly in Southeast Asia.

Molecular characterisation and expression analysis of two heat-shock proteins in Taenia multiceps

Background

Taenia multiceps is a harmful tapeworm and its larval form (coenurus cerebralis) is the causative agent of coenurosis, a disease affecting the health of herbivores, resulting in great economic loss to animal husbandry. Heat-shock proteins (HSPs), expressed in all prokaryotes and eukaryotes, act as molecular chaperones and can affect pathogenicity.

Methods

Herein, cDNAs of T. multiceps genes Tm-HSP60 and Tm-p36 were cloned and molecularly characterised by bioinformatics analyses. The immunogenicity and immunoreactivity of recombinant rTm-HSP60 and rTm-p36 proteins were investigated by immunoblotting and indirect ELISA was established to evaluate their serodiagnostic potential. Tissue localisation and transcriptional level at different life stages of T. multiceps were determined by immunohistochemical and quantitative real-time PCR analyses.

Result

The 533 residue rTm-HSP60 and the 314 residue rTm-p36 proteins share typical highly conserved features of HSPs. Tm-p36 shares structural characteristics with metazoan small HSPs, with two N-terminal α-crystallin domains. Compared with Tm-p36, Tm-HSP60 displayed stronger immunogenicity, and the indirect ELISA based on rTm-HSP60 exhibited a sensitivity of 83.3% and a specificity of 87.5%, while rTm-p36 was not suitable to develop indirect ELISA. Tm-HSP60 was widely distributed in all stages of T. multiceps, albeit at relatively low levels, while Tm-p36 was specifically distributed in the protoscolex and oncosphere.

Conclusions

The sequence, structural and functional analyses of these two HSPs indicates that they may play important roles in the life-cycle of T. multiceps as molecular chaperones. Tm-HSP60 displayed stronger immunogenicity compare to Tm-p36, and has the potential for antibody detection. Tm-p36 was strongly associated with the activation of oncospheres and has potential interest for vaccination.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3352-8) contains supplementary material, which is available to authorized users.

Development of a direct PCR assay to detect Taenia multiceps eggs isolated from dog feces

Taenia multiceps is a tapeworm that leads to the death of livestock, resulting in major economic losses worldwide. The adult stage of this parasite invades the small intestine of dogs and other canids. In the present study, we developed a direct PCR assay to detect T. multiceps eggs isolated from dog feces to help curb further outbreaks. The genomic DNA was rapidly released using a lysis buffer and the PCR reaction was developed to amplify a 433-bp fragment of the T. multiceps mitochondrial gene encoding NADH dehydrogenase subunit 5 (nad5) from eggs isolated from dog feces. The procedure could be completed within 3 h, including flotation. The sensitivity of the assay was determined by detecting DNA from defined numbers of eggs, and the specificity was determined by detecting DNA from other intestinal tapeworm and roundworm species that commonly infect dogs. In addition, 14 taeniid-positive fecal samples determined by the flotation technique were collected and further evaluated by the regular PCR and our direct PCR. The results showed that the direct PCR developed herein was sensitive enough to detect the DNA from as few as 10 T. multiceps eggs and that no cross-reactions with other tapeworm and roundworm were observed, suggesting its high sensitivity and specificity for T. multiceps detection. Moreover, 14 taeniid-positive samples were screened by the regular PCR and direct PCR, with detection rates of 78.6% and 85.7%, respectively. In conclusion, the direct PCR assay developed in the present study has high sensitivity and specificity to identify T. multiceps eggs isolated from dog feces and therefore could represent an invaluable tool to identify T. multiceps outbreaks and would contribute to future clinical applications.

Molecular cloing and bioinformatics analysis of lactate dehydrogenase from Taenia multiceps

Coenurus cerebralis, the larval stage (metacestode or coenurus) of Taenia multiceps, parasitizes sheep, goats, and other ruminants and causes coenurosis. In this study, we isolated and characterized complementary DNAs that encode lactate dehydrogenase A (Tm-LDHA) and B (Tm-LDHB) from the transcriptome of T. multiceps and expressed recombinant Tm-LDHB (rTm-LDHB) in Escherichia coli. Bioinformatic analysis showed that both Tm-LDH genes (LDHA and LDHB) contain a 996-bp open reading frame and encode a protein of 331 amino acids. After determination of the immunogenicity of the recombinant Tm-LDHB, an indirect enzyme-linked immunosorbent assay (ELISA) was developed for preliminary evaluation of the serodiagnostic potential of rTm-LDHB in goats. However, the rTm-LDHB-based indirect ELISA developed here exhibited specificity of only 71.42% (10/14) and sensitivity of 1:3200 in detection of goats infected with T. multiceps in the field. This study is the first to describe LDHA and LDHB of T. multiceps; meanwhile, our results indicate that rTm-LDHB is not a specific antigen candidate for immunodiagnosis of T. multiceps infection in goats.