The instantly blocking-based fluorescent immunochromatographic assay for the detection of SARS-CoV-2 neutralizing antibody

IntroductionAt present, there is an urgent need for the rapid and accurate detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibodies (NAbs) to evaluate the ability of the human body to resist coronavirus disease 2019 (COVID-19) after infection or vaccination. The current gold standard for neutralizing antibody detection is the conventional virus neutralization test (cVNT), which requires live pathogens and biosafety level-3 (BSL-3) laboratories, making it difficult for this method to meet the requirements of large-scale routine detection. Therefore, this study established a time-resolved fluorescence-blocking lateral flow immunochromatographic assay (TRF-BLFIA) that enables accurate, rapid quantification of NAbs in subjects.MethodsThis assay utilizes the characteristic that SARS-CoV-2 neutralizing antibody can specifically block the binding of the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and angiotensin-converting enzyme 2 (ACE2) to rapidly detect the content of neutralizing antibody in COVID-19-infected patients and vaccine recipients.ResultsWhen 356 samples of vaccine recipients were measured, the coincidence rate between this method and cVNT was 88.76%, which was higher than the coincidence rate of 76.97% between cVNT and a conventional chemiluminescence immunoassay detecting overall binding anti-Spike-IgG. More importantly, this assay does not need to be carried out in BSL-2 or 3 laboratories.DiscussionTherefore, this product can detect NAbs in COVID-19 patients and provide a reference for the prognosis and outcome of patients. Simultaneously, it can also be applied to large-scale detection to better meet the needs of neutralizing antibody detection after vaccination, making it an effective tool to evaluate the immunoprotective effect of COVID-19 vaccines

Role of chymotrypsin C in development and progression of pancreatitis and pancreatic cancer

Chymotrypsin C (CTRC) is a trypsinogen synthesized by pancreatic acinar cells and secreted by pancreatic duct cells and belongs to the family of serine chymotrypsin. The main function of CTRC is to regulate the balance between activation and degradation of trypsin and maintain the structural and functional integrity of the pancreas. CTRC gene mutations can cause abnormal activation of trypsinogen and abnormal degradation of trypsin and then lead to the development of pancreatitis. The downregulation or absence of CTRC expression may be associated with the development and metastasis of pancreatic cancer. This article introduces the structure and biological function of CTRC and its mechanism of action in the development and progression of pancreatitis and pancreatic cancer

Comprehensive understanding of DC pole-to-pole fault and its protection for modular multilevel converters

A modular multilevel converter (MMC) is one of the promising voltage source converter topologies in the field of high-voltage direct current (HVDC) transmission. MMCs are vulnerable to the direct current (DC) short-circuit faults due to the high discharge current stress. This study first introduced the simplified equivalent circuits of MMCs under both normal and DC fault operation conditions. Then the MMC fault spread loops and fault energy distribution principles are presented. Moreover, a detailed comparative study of the existing DC fault handling schemes, which are classified as the rigid blocking and flexible blocking methods are carried out. It provides a technical reference for further study on the MMC DC fault protection schemes for the HVDC transmission system