CRISPR/Cas12a and recombinase polymerase amplification-based rapid on-site nucleic acid detection of duck circovirus.

Duck circovirus (DuCV) infections commonly induce immunosuppression and secondary infections in ducks, resulting in significant economic losses in the duck breeding industry. Currently, effective vaccines and treatments for DuCV have been lacking. Therefore, rapid, specific, and sensitive detection methods are crucial for preventing and controlling DuCV. A lateral flow strip (LFS) detection method was developed using recombinase polymerase amplification (RPA) and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 12a (Cas12a). The RPA-CRISPR/Cas12a-LFS targeted the DuCV replication protein (Rep) and was operated at 37 ℃ and allowed for visual interpretation without requiring sophisticated equipment. The results revealed that the reaction time of RPA-CRISPR/Cas12a-LFS is only 45 min. This method achieved a low detection limit of 2.6 gene copies. Importantly, this method demonstrated high specificity and no cross-reactivity with six other avian viruses. In a study involving 97 waterfowl samples, the Rep RPA-CRISPR/Cas12a-LFS showed 100% consistency and agreement with real-time quantitative polymerase chain reaction. These findings underscored the potential of this user-friendly, rapid, sensitive, and accurate detection method for on-site DuCV detection.

Liang QZ ，Chen W ，Liu RC ，Fu QL ，Fu GH ，Cheng LF ，Chen HM ，Jiang NS ，Zhu T ，Huang Y ... -  《Virology Journal》

Detection of Porcine Circovirus (PCV) Using CRISPR-Cas12a/13a Coupled with Isothermal Amplification.

Wang H ，Zhou G ，Liu H ，Peng R ，Sun T ，Li S ，Chen M ，Wang Y ，Shi Q ，Xie X ... -  《-》

A loop-mediated isothermal amplification assay for the visual detection of duck circovirus.

Xie L ，Xie Z ，Zhao G ，Liu J ，Pang Y ，Deng X ，Xie Z ，Fan Q ，Luo S ... -  《-》

A rapid and ultra-sensitive dual readout platform for Klebsiella pneumoniae detection based on RPA-CRISPR/Cas12a.

The bacterium Klebsiella pneumoniae (Kp) was the primary pathogen of hospital-acquired infection, but the current detection method could not rapidly and conveniently identify Kp. Recombinase polymerase amplification (RPA) was a fast and convenient isothermal amplification technology, and the clustered regularly interspaced short palindromic repeats (CRISPR) system could rapidly amplify the signal of RPA and improve its limit of detection (LOD). In this study, we designed three pairs of RPA primers for the rcsA gene of Kp, amplified the RPA signal through single-strand DNA reporter cleavage by CRISPR/Cas12a, and finally analyzed the cleavage signal using fluorescence detection (FD) and lateral flow test strips (LFTS). Our results indicated that the RPA-CRISPR/Cas12a platform could specifically identify Kp from eleven common clinical pathogens. The LOD of FD and LFTS were 1 fg/μL and 10 fg/μL, respectively. In clinical sample testing, the RPA-CRISPR/Cas12a platform was consistent with the culture method and qPCR method, and its sensitivity and specificity were 100% (16/16) and 100% (9/9), respectively. With the advantages of detection speed, simplicity, and accuracy, the RPA-CRISPR/Cas12a platform was expected to be a convenient tool for the early clinical detection of Kp.

Tan M ，Liang L ，Liao C ，Zhou Z ，Long S ，Yi X ，Wang C ，Wei C ，Cai J ，Li X ，Wei G ... -  《Frontiers in Cellular and Infection Microbiology》

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

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. 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. 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. 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.

Shao G ，Zhu X ，Hua R ，Chen Y ，Yang G ... -  《PLoS Neglected Tropical Diseases》