Evaluation of a novel Dot-ELISA assay utilizing a recombinant protein for the effective diagnosis of Taenia pisiformis larval infections

Parasite-derived microRNA let-7-5p detection for metacestodiasis based on rolling circular amplification-assisted CRISPR/Cas9

Metacestodiasis is an infectious disease caused by the larval stage of cestode parasites. This disease poses a serious health hazard to wildlife, livestock, and humans, and it incurs substantial economic losses by impacting the safety of the livestock industry, the quality of meat production, and public health security. Unfortunately, there is currently no available molecular diagnostic method capable of distinguishing cysticercus- and Echinococcus-derived microRNAs (miRNAs) from other helminthes and hosts in the plasma of metacestode-infected animals. This study aims to develop a specific, sensitive, and cost-efficient molecular diagnostic method for cysticercosis and echinococcosis, particularly for early detection. The study developed a rolling circular amplification (RCA)-assisted CRISPR/Cas9 detection method based on parasite-derived miRNA let-7-5p. Using a series of dilutions of the let-7 standard, the limit of detection (LOD) of the qPCR, RCA, and RCA-assisted CRISPR/Cas9 methods was compared. The specificity of qPCR and CRISPR/Cas9 was evaluated using four artificially synthesized let-7 standards from different species. A total of 151 plasma samples were used to evaluate the diagnostic performance. Additionally, the study also assessed the correlation between plasma levels of let-7-5p, the number of Taenia pisiformis cysticerci, and the weight of Echinococcus multilocularis cysts. The results demonstrated that the RCA-assisted CRISPR/Cas9 assay could significantly distinguish let-7 from cestodes and other species, achieving a LOD of 10 aM; the diagnostic sensitivity and specificity for rabbit cysticercosis and mouse E. multilocularis were 100% and 97.67%, and 100% and 100%, respectively. Notably, let-7-5p gradually increased in the plasma of T. pisiformis-infected rabbits from 15 days post infection (dpi), peaked at 60 dpi, and persisted until 120 dpi. In E. multilocularis-infected mice, let-7-5p gradually increased from 15 dpi and persisted until 90 dpi. Furthermore, the expression of let-7-5p positively correlated with the number of cysticerci and cyst weight. These results indicated that the let-7-5p-based RCA-assisted CRISPR/Cas9 assay is a sensitive and specific detection method that can be used as a universal diagnostic method for metacestodiasis, particularly for early diagnosis (15 dpi).

Identification and Expression Profiling of Circulating MicroRNAs in Serum of Cysticercus pisiformis-Infected Rabbits

Cysticercus pisiformis (C. pisiformis), the larval form of Taenia pisiformis, parasitize mainly the liver, omentum and mesentery of rabbits and cause huge economic losses in the rabbit breeding industry. MicroRNA (miRNA), a short non-coding RNA, is widely and stably distributed in the plasma and serum. Numerous data demonstrates that, after parasitic infection, miRNAs become the key regulatory factor for controlling host biological processes. However, the roles of serum miRNAs in C. pisiformis-infected rabbits have not been elucidated. In this study, we compared miRNA expression profiles between the C. pisiformis-infected and healthy rabbit serum using RNA-seq. A total of 192 miRNAs were differentially expressed (fold change ≥ 2 and p < 0.05), including 79 up- and 113 downregulated miRNAs. These data were verified by qRT-PCR (real time quantitative polymerase chain reaction) analysis. Additionally, GO analysis showed that the target genes of these dysregulated miRNAs were most enriched in cellular, single-organism and metabolic processes. KEGG pathway analysis showed that these miRNAs target genes were involved in PI3K-Akt, viral carcinogenesis and B cell receptor signaling pathways. Interestingly, after aligning clean reads to the T. pisiformis genome, four (miR-124-3p_3, miR-124-3p_4, miR-124a and novel-miR1) T. pisiformis-derived miRNAs were found. Of these, novel-miR1was upregulated in different periods after C. pisiformis infection, which was verified qRT-PCR, and pre- novel-miR-1 was amplified from the cysticerci by RT-PCR, implying novel-miR-1 was derived from C. pisiformis and has great potential for the diagnosis of Cysticercosis pisiformis infection. This is the first investigation of miRNA expression profile and function in the serum of rabbits infected by C. pisiformis, providing fundamental data for developing diagnostic targets for Cysticercosis pisiformis.

Generation and application of a monoclonal antibody against the 18-kDa oncosphere antigen of Taenia pisiformis

Taenia pisiformis is a parasite that causes cysticercosis pisiformis, which has acquired economic relevance because of its effects on animal welfare and production. A useful assay for the detection of T. pisiformis is needed for the prevention of cysticercosis pisiformis and control of the parasite. The 18-kDa oncosphere antigen is expressed in the oncosphere of several cysticerci in species of the genus Taenia, including T. pisiformis. This protein plays an important role in tissue invasion and has extensive applications in diagnosis. In this study, the T. pisiformis 18-kDa oncosphere antigen (TPO18) was expressed in soluble form and successfully purified for use in the production of monoclonal antibodies (MAbs) against TPO18. Twenty hybridomas were obtained using ELISA, and the subcloning process identified three positive hybridoma cell lines, which were designated as 4E8, 5G5, and 7E8. MAb 7E8 exhibited the highest titer and had an IgG2b heavy chain and a kappa light chain. Western blot analysis demonstrated that MAb 7E8 reacted with GST-TPO18. Immunohistochemistry showed that TPO18 was widely distributed in the drape and wall of uteri in adults of T. pisiformis adults and in the fibrous layer of the sucker and cyst cavity of T. pisiformis cysticerci. This research will provide a foundation for the development of diagnostic tools and will contribute to a better understanding of the functions of TPO18.

A multiplex PCR assay for the simultaneous detection of Taenia hydatigena, T. multiceps, T. pisiformis, and Dipylidium caninum infections

Background

Taenia hydatigena, T. multiceps, T. pisiformis, and Dipylidium caninum are four common large and medium-sized tapeworms parasitizing the small intestine of dogs and other canids. These parasites cause serious impact on the health and development of livestock. However, there are, so far, no commercially available molecular diagnostic kits capable of simultaneously detecting all four parasites in dogs. The aim of the study was therefore to develop a multiplex PCR assay that will accurately detect all four cestode infections in one reaction.

Methods

Specific primers for a multiplex PCR were designed based on corresponding mitochondrial genome sequences, and its detection limit was assessed by serial dilutions of the genomic DNAs of tapeworms examined. Furthermore, field samples of dog feces were tested using the developed assay.

Results

A multiplex polymerase chain reaction (PCR) assay was developed based on mitochondrial DNA (mtDNA) that accurately and simultaneously identify four cestode species in one reaction using specific fragment sizes of 592, 385, 283, and 190 bp for T. hydatigena, T. multiceps, T. pisiformis, and D. caninum, respectively. The lowest DNA concentration detected was 1 ng for T. hydatigena, T. multiceps and T. pisiformis, and 0.1 ng for D. caninum in a 25 μl reaction system. This assay offers high potential for the rapid detection of these four tapeworms in host feces simultaneously.

Conclusions

This study provides an efficient tool for the simultaneous detection of T. hydatigena, T. multiceps, T. pisiformis, and D. caninum. The assay will be potentially useful in epidemiological studies, diagnosis, and treatment of these four cestodes infections during prevention and control program.

Lethal cysticercosis in a pet rabbit

A one-year-old neutered female crossbreed rabbit died unexpectedly after initially responding to symptomatic treatment over a three-month period for recurrent gut stasis, inappetence and lethargy. Postmortem examination revealed numerous fibrous tracks within the liver from which flattish ovoid parasites could be extruded. Parasites were also found in large numbers throughout the peritoneal cavity. Histopathology confirmed verminous hepatitis with numerous parasitic granulomas within the parenchyma of the liver containing intact and degenerate parasites. The severity of the parasitic burden and associated liver damage was the presumed cause of death. Intact parasites showed morphological features consistent with Taenia pisiformis at 6–15 days postinfection. Species identification was confirmed by PCR sequence analysis. The rabbit was fed on hay sourced from a local farm, commercially available nuggets and washed vegetables. It did not graze outside. Hay contaminated with dog or fox faeces was the presumed source of infection.

Development of dot-ELISA for the detection of venoms of major Indian venomous snakes

India remained an epicenter for the snakebite-related mortality and morbidities due to widespread agricultural activities across the country and a considerable number of snakebites offended by Indian cobra (Naja naja), common krait (Bungarus caeruleus), Russell's viper (Daboia russelii), and saw-scaled viper (Echis carinatus). Presently, there is no selective test available for the detection of snake envenomation in India before the administration of snake antivenin. Therefore, the present study aimed to develop rapid, sensitive assay for the management of snakebite, which can detect venom, responsible snake species and serve as a tool for the reasonable administration of snake antivenin, which have scarcity across the world. The selective envenomation detection assay needs venom specific antibodies (VSAbs) for that monovalent antisera was prepared by hyperimmunization of rabbits with specific venom. However, obtained antibodies exhibit maximum activity towards homologous venom as well as quantifiable degree of cross-reactivity with heterologous venoms. Use of these antibodies for development of selective envenomation detection assay may create ambiguity in results, therefore needs to isolate VSAbs from monovalent antisera. The cross-reacting antibodies were specifically removed by immunoaffinity chromatography to obtain VSAbs. For the development of venom detection ELISA test (VDET), two different species of antibodies were used that offers enhanced sensitivity along with selective identification of the venoms of the responsible snakes. In conclusion, the developed VDET is rapid, specific, yet sensitive to detect venoms of offending snake species, and its venom concentration down to 1.0 ng/ml. However, the device observed with lowest venom concentration detection ability in the range <1.0 ng/ml from experimentally envenomated samples. The implementation of VDET will help in avoiding unnecessary usage and adverse reactions of snake antivenin. The test has all the merits to become a choice of method in envenomation diagnosis from medically important snakes of India.