Development and evaluation of an external quality control and internal quality control containing real-time RT-PCR assay for the detection of o'nyong-nyong virus.

O'nyong-nyong fever is a mosquito-borne tropical viral disease while few molecular diagnostic tools have been established for its surveillance until now. In the current study, a single-step, dual-color real-time reverse transcription polymerase chain reaction (RT-PCR) assay which contained both external quality control (EQC) and internal quality control (IQC) prepared by armored RNA technique was developed and evaluated for the detection of o'nyong-nyong virus (ONNV). Results showed that the assay was established successfully without cross-reaction with genetically related or symptom-alike diseases, which showed high specificity of the assay. The coefficient of variation of the assay was 0.97%, far less than 5%, indicating good repeatability of the assay. The lower limit of detection of the assay could reach as low as 100 copies of genome equivalent. During evaluation, the assay could correctly detect ONNV from spiked human serum samples and Anopheles species mosquito samples, while no ONNV positive was observed either from serum samples of patients with acute febrile illness or from local Anopheles species mosquitoes, suggesting no ONNV had been transmitted locally. In conclusion, the assay could potentially provide a valuable platform for ONNV molecular detection, which may improve the preparedness for future o'nyong-nyong fever outbreaks.

Joint Detection of Serum Vitamin D, Body Mass Index, and Tumor Necrosis Factor Alpha for the Diagnosis of Crohn's Disease.

OBJECTIVE: Vitamin D (VD) deficiency was reported to contribute to the progression of Crohn's disease (CD) and affect the prognosis of CD patients. This study investigated the role of serum VD, body mass index (BMI), and tumor necrosis factor alpha (TNF-α) in the diagnosis of Crohn's disease. METHODS: CD patients (n=76) and healthy subjects (n=76) were enrolled between May 2019 and December 2020. The serum 25-hydroxyvitamin D [25(OH)D] levels, BMI, and TNF-α levels, together with other biochemical parameters, were assessed before treatment. The diagnostic efficacy of the single and joint detection of serum 25(OH)D, BMI, and TNF-α was determined using receiver operating characteristic (ROC) curves. RESULTS: The levels of 25(OH) D, BMI, and nutritional indicators, including hemoglobin, total protein, albumin, and high-density lipoprotein cholesterol, were much lower, and the TNF-α levels were much higher in the CD patients than in the healthy subjects (P<0.05 for all). The areas under the ROC curve for the single detection of 25(OH)D, BMI, and TNF-α were 0.887, 0.896, and 0.838, respectively, with the optimal cutoff values being 20.64 ng/mL, 19.77 kg/m2, and 6.85 fmol/mL, respectively. The diagnostic efficacy of the joint detection of 25(OH)D, BMI, and TNF-α was the highest, with an area under the ROC curve of 0.988 (95%CI: 0.968-1.000). CONCLUSION: The joint detection of 25(OH)D, TNF-α, and BMI showed high sensitivity, specificity, and accuracy in CD diagnosis; thus, it would be effective for the diagnosis of CD in clinical practice.

A High-throughput Platform for the Screening of Salmonella spp./Shigella spp.

Fecal-oral transmission of acute gastroenteritis occurs from time to time, especially when people who handled food and water are infected by Salmonella spp./Shigella spp. The gold standard method for the detection of Salmonella spp./Shigella spp. is direct culture but this is labor-intensive and time-consuming. Here, we describe a high-throughput platform for Salmonella spp./Shigella spp. screening, using real-time polymerase chain reaction (PCR) combined with guided culture. There are two major stages: real-time PCR and the guided culture. For the first stage (real-time PCR), we explain each step of the method: sample collection, pre-enrichment, DNA extraction and real-time PCR. If the real-time PCR result is positive, then the second stage (guided culture) is performed: selective culture, biochemical identification and serological characterization. We also illustrate representative results generated from it. The protocol described here would be a valuable platform for the rapid, specific, sensitive and high-throughput screening of Salmonella spp./Shigella spp.

Verification and large scale clinical evaluation of a national standard protocol for Salmonella spp./Shigella spp. screening using real-time PCR combined with guided culture.

Salmonella spp./Shigella spp. are often associated with food poisoning and fecal-oral transmission of acute gastroenteritis that requires strict monitoring, especially among people who would handle food and water. In 2014, the National Health and Family Planning Commission of the P. R. China issued a national standard protocol (recommendatory) for the screening of Salmonella spp./Shigella spp.. However, its performance has not been fully studied. Whether it was suitable for use in our laboratory was still unknown. In the current study, the new protocol was first verified by various experiments and then its clinical performance was evaluated in about 20,000 stool samples over a three-year period. Verification results showed that the new protocol was highly specific and reproducible. Sensitivity (as defined as the lower limit of detection) of the new protocol at the PCR step was 103CFU/mL and 101CFU/mL for Salmonella spp. and Shigella spp., while that at the guided culture step was 104CFU/mL and 103CFU/mL, respectively. The large scale clinical evaluation indicated that the new protocol could increase the positivity rate by two fold and decrease the workload/median turnaround time significantly. In conclusion, the protocol was verified and evaluated and was proven to be a valuable platform for the rapid, specific, sensitive and high-throughput screening of Salmonella spp./Shigella spp.