Comparison of multiplex copro PCR with coproscopy followed by PCR on recovered eggs for the detection of Echinococcus granulosus and Taenia spp. infection in dogs

Development of a Copro-RPA-CRISPR/Cas12a assay to detect Echinococcus granulosus nucleic acids isolated from canine feces using NaOH-based DNA extraction method

BACKGROUND

Cystic echinococcosis (CE), caused by Echinococcus granulosus sensu lato (E. granulosus s.l.), remains a significant zoonotic parasitic disease affecting both livestock and humans. It arises from the ingestion of food and water contaminated with canine feces containing E. granulosus eggs. The detection of these eggs in canine feces is essential for guiding effective preventative measures against the disease. Therefore, the development of a novel accurate, rapid, and visually interpretable point-of-care test is crucial for controlling CE.

METHODS

We combined recombinase polymerase amplification (RPA) and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) with a CRISPR-associated protein 12a (Cas12a) system, forming the RPA-CRISPR/Cas12a assay. This assay targeted the E. granulosus mitochondrial nad2 gene and utilized a lateral flow strip for visual readout. To improve field applicability, we integrated a simple and cost-effective NaOH-Based DNA extraction method. Clinical validation included testing DNA extracted from eighteen canine fecal samples, followed by comparison with quantitative PCR (qPCR) and two commercial enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

The RPA-CRISPR/Cas12a assay showed a detection limit of 1 fg/μL DNA, without any cross-reactivity with related tapeworms such as Echinococcus multilocularis, Dipylidium caninum, Taenia hydatigera, Taenia multiceps, and Taenia pisiformis. When applied to 62 clinical fecal samples from dogs, the RPA-CRISPR/Cas12a assay demonstrated 68% sensitivity, while the developed RPA-CRISPR/Cas12a-NaOH assay exhibited 45% sensitivity. In the field performance comparison of the RPA-CRISPR/Cas12a and the RPA-CRISPR/Cas12a-NaOH assay with qPCR and two ELISA kits, the sensitivity, consistency rate, and Youden's index suggested good or fair agreement with the currently employed detection methods.

CONCLUSION

This study describes the development and validation of the RPA-CRISPR/Cas12a and RPA-CRISPR/Cas12a-NaOH assays for detecting E. granulosus in canine feces. The developed assays surpassed previous detection methods in providing enhanced diagnostic sensitivity and enabling point-of-care testing. Moreover, these assays hold potential for surveilling E. granulosus in low-income countries.

Prevalence and geographic distribution of Echinococcus genus in wild canids in southern Québec, Canada

Echinococcus spp. is an emerging zoonotic parasite of high concern. In Canada, an increase in the number of human and animal cases diagnosed has been reported, but information regarding the parasite's distribution in wildlife reservoir remains limited. A cross-sectional study was conducted to estimate the prevalence of wild canids infected with Echinococcus spp. and Echinococcus multilocularis in areas surrounding populated zones in Québec (Canada); to investigate the presence of areas at higher risk of infection; to evaluate potential risk factors of the infection; and as a secondary objective, to compare coproscopy and RT-PCR diagnostic tests for Taenia spp. and Echinococcus identification. From October 2020 to March 2021, fecal samples were collected from 423 coyotes (Canis latrans) and 284 red foxes (Vulpes vulpes) trapped in 12 administrative regions. Real-time PCR for molecular detection of genus Echinococcus spp. and species-specific Echinococcus multilocularis were performed. A total of 38 positive cases of Echinococcus spp., of which 25 were identified as E. multilocularis, were detected. Two high-risk areas of infection were identified. The prevalence of Echinococcus spp. was 22.7% (95% CI 11.5-37.8%) in the Montérégie centered high-risk area, 26.5% (95% CI 12.9-44.4%) in the Bas-St-Laurent high-risk area, and 3.0% (95%CI 1.8-4.7%) outside those areas. For E. multilocularis, a prevalence of 20.5% (95% CI 9.8-35.3%) was estimated in the high-risk area centered in Montérégie compared to 2.4% (95% CI 1.4-3.9%) outside. Logistic regression did not show any association of infection status with species, sex, or geolocation of capture (p > 0.05). This study shows the circulation of Echinococcus in a wildlife cycle in 9/12 administrative regions of Québec.

Advances in signal amplification strategies applied in pathogenic bacteria apta-sensing analysis-A review

Pathogenic bacteria are primarily kinds of food hazards that provoke serious harm to human health via contaminated or spoiled food. Given that pathogenic bacteria continue to reproduce and expand once they contaminate food, pathogenic bacteria of high concentration triggers more serious losses and detriments. Hence, it is essential to detect low-dose pollution at an early stage with high sensitivity. Aptamers, also known as "chemical antibodies", are oligonucleotide sequences that have attracted much attention owing to their merits of non-toxicity, small size, variable structure as well as easy modification of functional group. Aptamer-based bioanalysis has occupied a critical position in the field of rapid detection of pathogenic bacteria. This is attributed to the unique advantage of using aptamers as recognition elements in signal amplification strategies. The signal amplification strategy is an effective means to improve the detection sensitivity. Some diverse signal amplification strategies emphasize the synthesis and assembly of nanomaterials with signal amplification capabilities, while others introduce various nucleic acid amplification techniques into the detection system. This review focuses on a variety of signal amplification strategies employed in aptamer-based detection approaches to pathogenic bacteria. Meanwhile, we provided a detailed introduction to the design principles and characteristics of signal amplification strategies, as well as the improvement of sensor sensitivity. Ultimately, the existing issues and development trends of applying signal amplification strategies in apta-sensing analysis of pathogenic bacteria are critically proposed and prospected. Overall, this review discusses from a new perspective and is expected to contribute to the further development of this field.