An accurate assay for HCV based on real-time fluorescence detection of isothermal RNA amplification

Early Diagnosis of Mycoplasma pneumoniae in Children: Simultaneous Amplification and Testing (SAT) Is the Key

Objective: The effective diagnosis of Mycoplasma pneumoniae (MP) pneumonia (MPP) in children has been hampered by the difficulty of achieving an early diagnosis. The simultaneous amplification and testing (SAT) has the potential for early diagnosis of MP in children. Methods: Of the 1,180 children enrolled in this study, 169 were MPP antibody (Ab) seroconversion positive, 641 showed MPP positivity with a single Ab test, and 370 were MPP negative. Sera and pharyngeal swabs were collected for antibody testing and SAT detection, respectively, on admission. When the samples were Ab negative, the paired -Ab test was requested for MP 7 days later. Results: Using the Ab results as the diagnostic standard, the sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) for SAT were 72.8, 95.1, 97.0, and 61.5%, respectively. SAT had superior diagnostic value in the MPP group who had undergone Ab seroconversion (sensitivity: 82.2%; NPV: 92.1%) and in the short-course group also (sensitivity: 81.0%; NPV: 81.3%). Good agreement was observed between SAT and the paired-Ab results (kappa value = 0.79; P < 0.001), but there was a lack of consistency between SAT and the single-Ab test results on admission (kappa value = 0.54, P < 0.001). Conclusions: SAT is a rapid, sensitive, and specific method for MP diagnosis in pediatric patients. Our results indicate its value as an effective diagnostic tool for detecting MPP at the initial stage of an infection.

Evaluation of a real-time method of simultaneous amplification and testing in diagnosis of Mycoplasma pneumoniae infection in children with pneumonia

Mycoplasma pneumoniae (M. pneumoniae) infection can cause community acquired pneumonia in children. A real-time method of simultaneous amplification and testing of M. pneumoniae (SAT-MP) was developed to diagnose M. pneumoniae targeting a region of the ribosomal RNA. The SAT-MP assay can accurately identify M. pneumoniae with a detection range from 10¹ to 10⁷ CFU/ml. In this study, the specimens from 315 children with pneumonia were collected and analyzed by SAT-MP in parallel with real-time PCR method and IgM ELISA assay. The positive rates of these specimens examined by SAT-MP assay, real-time PCR method and IgM ELISA assay were 16.51%, 15.56% and 12.70% respectively. While there was statistical significance (p = 0.04) between SAT-MP assay and IgM ELISA assay, no statistical significance (p = 0.25) was found between SAT-MP assay and real-time PCR method and these two methods had high consistency (kappa value = 0.97). These findings indicate that the newly developed SAT-MP assay is a rapid, sensitive and specific method for identifying M. pneumoniae with potential clinical application in the early diagnosis of M. pneumoniae infection.

An improved gold nanoparticle probe-based assay for HCV core antigen ultrasensitive detection

A gold nanoparticle probe-based assay (GNPA) was developed for ultrasensitive detection of Hepatitis C virus (HCV) core antigen. In the GNPA, after anti-HCV core antigen polyclonal antibodies and single-stranded barcode signal DNA were labeled on gold nanoparticle probe (NP), DNA enzyme was used to degrade the unbound barcode DNAs. The anti-HCV core antigen monoclonal antibodies were coated on magnetic microparticles probe (MMP). Then the NP-HCV core antigen-MMP sandwich immuno-complex was formed when the target antigen protein was added and captured. Magnetically separated, the immuno-complex containing the single-stranded barcode signal DNA was characterized by TaqMan probe based real-time fluorescence PCR. A detection limit of 1 fg/ml was determined for the HCV core antigen which is magnitude greater than that of ELISA (2ng/ml). The coefficients of variation (CV) of intra-assay and inter-assay respectively ranged from 0.22-2.62% and 1.92-3.01%. The improved GNPA decreased the interference of unbound barcode DNAs and may be an new way for HCV core antigen detection.