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An isothermal CRISPR-based diagnostic assay for Neisseria gonorrhoeae and Chlamydia trachomatis detection.

ABSTRACT: The occurrence of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) is increasing worldwide, particularly in low- and middle-income countries. In cases where most infections are asymptomatic and remain in a coinfection condition. It may cause missed detections or the severe subsequent symptoms. Accurate diagnosis and convenient screening are essential for disease control. However, molecular diagnostics for CT/NG predominantly rely on polymerase chain reaction (PCR)-based detection, which requires special devices and conditions. Here, we developed an isothermal CRISPR-based CT/NG dual-target detection system by pairing recombinase polymerase amplification (RPA) and CRISPR-Cas12a/13a detection. Multiplex RPA can amplify NG and CT simultaneously, and a single-pot reaction with the Cas12a/13a can be performed for further recognizing the amplified target, driving the cleavage of the corresponding fluorescence reporter separately; thus, the signal can be monitored in different channels. This CRISPR-based CT/NG detection system achieved analytical sensitivities of 10° copies/μL for both synthetic CT/NG dsDNA and exhibited no cross-reaction with other species. In tests on 88 clinical samples, our CRISPR-based assay showed excellent agreement with the commercial assay Roche Cobas 4800 (100% accuracy for NG, 94.32% accuracy for CT, and 97.73% accuracy for CT/NG coinfection) and showed higher positive percent agreement, negative percent agreement, and accuracy than those reported for TaqMan PCR in a previous study. In addition, the results of this CRISPR-based system could be acquired within 75 min. Our isothermal diagnostic method with promising performance provides more convenience than PCR-based methods for detection and screening.IMPORTANCEA method for Neisseria gonorrhoeae (NG)/Chlamydia trachomatis (CT) detection is developed using multiplex-recombinase polymerase amplification and Cas12a/Cas13a. This method can detect NG and CT simultaneously with high sensitivity and specificity. This method has great potential to be further developed into larger-scale screening and point-of-care testing (POCT).

SUBMITTER: Luo H

PROVIDER: S-EPMC10715037 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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An isothermal CRISPR-based diagnostic assay for <i>Neisseria gonorrhoeae</i> and <i>Chlamydia trachomatis</i> detection.

Luo Hao H Zeng Lihong L Yin Xiaona X Pan Yuying Y Yang Jianjiang J Liu Mingjing M Qin Xiaolin X Feng Zhanqin Z Chen Wentao W Zheng Heping H

Microbiology spectrum 20231026 6

<h4>Importance</h4>A method for <i>Neisseria gonorrhoeae</i> (NG)/<i>Chlamydia trachomatis</i> (CT) detection is developed using multiplex-recombinase polymerase amplification and Cas12a/Cas13a. This method can detect NG and CT simultaneously with high sensitivity and specificity. This method has great potential to be further developed into larger-scale screening and point-of-care testing (POCT). ...[more]

PMID: 37882532

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Project description:BackgroundNeisseria meningitidis can cause life-threatening meningococcal meningitis and meningococcemia. Old standard microbiological results from CSF/blood cultures are time consuming. This study aimed to combine the sensitivity of loop-mediated isothermal nucleic acid amplification (LAMP) with the specificity of CRISPR/Cas12a cleavage to demonstrate a reliable diagnostic assay for rapid detection of N. meningitidis.MethodsA total of n = 139 samples were collected from patients with suspected meningococcal disease and were used for evaluation. The extracted DNA was subjected to qualitative real-time PCR, targeting capsular transporter gene (ctrA) of N. meningitidis. LAMP-specific primer pairs, also targeting the ctrA, were designed and the LAMP products were subjected to CRISPR/Cas12 cleavage reaction. the readout was on a lateral flow strip. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of LAMP-CRISPR/Cas was compared with real-time PCR assays. The limit of detection (LOD) was established with serial dilutions of the target N. meningitidis DNA and calculated by Probit regression analysis.ResultsSix LAMP assay-specific primers were developed targeting the ctrA gene of N. meningitidis, which is conserved in all meningococcal serogroups. The LAMP primers did not amplify DNA from other bacterial DNA tested, showing 100% specificity. The use of 0.4 M betaine increased the sensitivity and stability of the reaction. LAMP-CRISPR/Cas detected meningococcal serogroups (B, C, W). The assay showed no cross-reactivity and was specific for N. meningitidis. The LOD was 74 (95% CI: 47-311) N. meningitidis copies. The LAMP-CRISPR/Cas performed well compared to the gold standard. In the 139 samples from suspected patients, the sensitivity and specificity of the test were 91% and 99% respectively.ConclusionThis developed and optimized method can complement for the available gold standard for the timely diagnosis of meningococcal meningitis and meningococcemia.

Project description:BackgroundLaboratory detection of Human papillomavirus (HPV), Chlamydia trachomatis and Neisseria gonorrhoeae in liquid-based cervicovaginal cytology specimens is now based on identification of the DNA sequences unique to these infectious agents. However, current commercial test kits rely on nucleotide probe hybridization to determine DNA sequences, which may lead to diagnostic errors due to cross-reactivity. The aim of this study was to find a practical approach to perform automated Sanger DNA sequencing in clinical laboratories for validation of the DNA tests for these three infectious agents.MethodsA crude proteinase K digest of 5% of the cells collected in a liquid-based cervicovaginal cytology specimen was used for the detection of DNA molecules specific for HPV, C trachomatis and N gonorrhoeae, and for preparation of materials suitable for direct automated DNA sequencing. Several sets of commercially available polymerase chain reaction (PCR) primers were used to prepare nested PCR amplicons for direct DNA sequencing.ResultsSome variants of HPV-16 and HPV-31 were found to share an at least 34-base long sequence homology downstream of the GP5+ binding site, and all HPV-6 and HPV-11 variants shared an upstream 34-base sequence including part of the GP5+ primer. Accurate HPV genotyping frequently required more than 34-bases for sequence alignments to distinguish some of the HPV genotype variants with closely related sequences in this L1 gene hypervariable region. Using the automated Sanger DNA sequencing method for parallel comparative studies on split samples and to retest the residues of samples previously tested positive for C trachomatis and/or for N gonorrhoeae, we also found false-negative and false-positive results as reported by two commercial nucleic acid test kits.ConclusionIdentification of a signature DNA sequence by the automated Sanger method is useful for validation of HPV genotyping and for molecular testing of C trachomatis and N gonorrhoeae in liquid-based cervicovaginal Papanicolaou (Pap) cytology specimens for clinical laboratories with experience in molecular biology to increase the specificity of these DNA-based tests. However, even a highly specific test for high-risk HPV genotyping may have unacceptably low positive predictive values for precancer lesion in populations with a low cervical cancer prevalence rate.

Dataset Information

An isothermal CRISPR-based diagnostic assay for Neisseria gonorrhoeae and Chlamydia trachomatis detection.

Publications

An isothermal CRISPR-based diagnostic assay for <i>Neisseria gonorrhoeae</i> and <i>Chlamydia trachomatis</i> detection.

Similar Datasets

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