Ultrapotent SARS-CoV-2 neutralizing antibodies with protective efficacy against newly emerged mutational variants

Accumulating mutations in the SARS-CoV-2 Spike (S) protein can increase the possibility of immune escape, challenging the present COVID-19 prophylaxis and clinical interventions. Here, 3 receptor binding domain (RBD) specific monoclonal antibodies (mAbs), 58G6, 510A5 and 13G9, with high neutralizing potency blocking authentic SARS-CoV-2 virus displayed remarkable efficacy against authentic B.1.351 virus. Each of these 3 mAbs in combination with one neutralizing Ab recognizing non-competing epitope exhibited synergistic effect against authentic SARS-CoV-2 virus. Surprisingly, structural analysis revealed that 58G6 and 13G9, encoded by the IGHV1-58 and the IGKV3-20 germline genes, both recognized the steric region S470-495 on the RBD, overlapping the E484K mutation presented in B.1.351. Also, 58G6 directly bound to another region S450-458 in the RBD. Significantly, 58G6 and 510A5 both demonstrated prophylactic efficacy against authentic SARS-CoV-2 and B.1.351 viruses in the transgenic mice expressing human ACE2 (hACE2), protecting weight loss and reducing virus loads. These 2 ultrapotent neutralizing Abs can be promising candidates to fulfill the urgent needs for the prolonged COVID-19 pandemic.

A key linear epitope for a potent neutralizing antibody to SARS-CoV-2 S-RBD

The spread of SARS-CoV-2 confers a serious threat to the public health without effective intervention strategies1-3. Its variant carrying mutated Spike (S) protein D614G (SD614G) has become the most prevalent form in the current global pandemic4,5. We have identified a large panel of potential neutralizing antibodies (NAbs) targeting the receptor-binding domain (RBD) of SARS-CoV-2 S6. Here, we focused on the top 20 potential NAbs for the mechanism study. Of them, the top 4 NAbs could individually neutralize both authentic SARS-CoV-2 and SD614G pseudovirus efficiently. Our epitope mapping revealed that 16/20 potent NAbs overlapped the same steric epitope. Excitingly, we found that one of these potent NAbs (58G6) exclusively bound to a linear epitope on S-RBD (termed as 58G6e), and the interaction of 58G6e and the recombinant ACE2 could be blocked by 58G6. We confirmed that 58G6e represented a key site of vulnerability on S-RBD and it could positively react with COVID-19 convalescent patients plasma. We are the first, as far as we know, to provide direct evidences of a linear epitope that can be recognized by a potent NAb against SARS-CoV-2 S-RBD. This study paves the way for the applications of these NAbs and the potential safe and effective vaccine design.

A rapid and efficient screening system for neutralizing antibodies and its application for the discovery of potent neutralizing antibodies to SARS-CoV-2 S-RBD

Neutralizing antibodies (Abs) have been considered as promising therapeutics for the prevention and treatment of pathogens. After the outbreak of COVID-19, potent neutralizing Abs to SARS-CoV-2 were promptly developed, and a few of those neutralizing Abs are being tested in clinical studies. However, there were few methodologies detailly reported on how to rapidly and efficiently generate neutralizing Abs of interest. Here, we present a strategically optimized method for precisive screening of neutralizing monoclonal antibodies (mAbs), which enabled us to identify SARS-CoV-2 receptor-binding domain (RBD) specific Abs within 4 days, followed by another 2 days for neutralization activity evaluation. By applying the screening system, we obtained 198 Abs against the RBD of SARS-CoV-2. Excitingly, we found that approximately 50% (96/198) of them were candidate neutralizing Abs in a preliminary screening of SARS-CoV-2 pseudovirus and 20 of these 96 neutralizing Abs were confirmed with high potency. Furthermore, 2 mAbs with the highest neutralizing potency were identified to block authentic SARS-CoV-2 with the half-maximal inhibitory concentration (IC50) at concentrations of 9.88 ng/ml and 11.13 ng/ml. In this report, we demonstrated that the optimized neutralizing Abs screening system is useful for the rapid and efficient discovery of potent neutralizing Abs against SARS-CoV-2. Our study provides a methodology for the generation of preventive and therapeutic antibody drugs for emerging infectious diseases.

A Peptide-based Magnetic Chemiluminescence Enzyme Immunoassay for Serological Diagnosis of Corona Virus Disease 2019 (COVID-19)

A respiratory illness has been spreading rapidly in China, since its outbreak in Wuhan city, Hubei province in December 2019. The illness was caused by a novel coronavirus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Clinical manifestations related to SARS-CoV-2 infection ranged from no symptom to fatal pneumonia. World Health Organization (WHO) named the diseases associated with SARS-CoV-2 infection as COVID-19. Real time RT-PCR is the only laboratory test available till now to confirm the infection. However, the accuracy of real time RT-PCR depends on many factors, including sampling location and of methods, quality of RNA extraction and training of operators etc.. Variations in these factors might significantly lower the sensitivity of the detection. We developed a peptide-based luminescent immunoassay to detect IgG and IgM. Cut-off value of this assay was determined by the detection of 200 healthy sera and 167 sera from patients infected with other pathogens than SARS-CoV-2. To evaluate the performance of this assay, we detected IgG and IgM in the 276 sera from confirmed patients. The positive rate of IgG and IgM were 71.4% (197/276) and 57.2% (158/276) respectively. By combining with real time RT-PCR detection, this assay might help to enhance the accuracy of diagnosis of SARS-CoV-2 infection.

Clinical research progress of refractory wounds treated by Traditional Chinese Medicine combined with VSD / 国际中医中药杂志

This article systematically reviewed the clinical research of Traditional Chinese Medicine (TCM) combined with Vacuum Sealing Drainage (VSD) in the treatment of refractory wounds. The results showed that TCM combined with VSD for refractory wounds was characterized by abundent treatment and effectiveness. Treatments such as oral administration of TCM decoction, injection and lavage administration of TCM decoction, and external application of TCM ointment can reduce the level of inflammation in the wound, improve local microcirculation, promote granulation tissue growth and wound healing, and improve clinical efficacy. This paper summarized the clinical researches on the treatment of refractory wounds by TCM and VSD, and provide a useful reference for clinical treatment of refractory wounds.

Content Analysis and Comparative Study of Amino Acids in Ejiao from 18 Manufacturers / 中国药房

OBJECTIVE:To provide reference for quality evaluation of Ejiao. METHODS:The contents of 17 amino acids in 18 batches of Ejiao from 18 manufacturers were analyzed by automatic amino acid analyzer;the content data was processed by prin-cipal component analysis (PCA) and hierarchical clustering analysis (HCA),in order to understand the relationship among these amino acids and categorize the Ejiao products. RESULTS:Except for a batch of Ejiao,the other 17 batches contained 17 various amino acids,including 7 necessary amino acids(Thr,Val,Met,Ile,Leu,Phe and Lys)for human being,especially the contents of Gly and Pro were higher. The total content of amino acids was arranged from 66.1% to 82.0%,showing great difference. Four main components were extracted by PCA,the cumulative contribution of which was 89.578%,and accordingly it may be consid-ered that Pro,Ala,Glu,Asp,Leu,Ile and Thr were characteristic amino acids of Ejiao products. In hierarchical clustering analy-sis,3 tree figures of commercial Ejiao product were achieved and Euclidean distance was varied among 0-25. CONCLUSIONS:There is great difference in total control of amino acid in commercial Ejiao product;Ejiao products from various manufacturers dif-fer in their amino acid contents. Ejiao is rich in collagen,and therefore,using amino acid determination would be helpful to moni-tor its quality.

Preparation and biocompatibility of poly ester-amide electrospinning nanofiber membrane / 中国组织工程研究

The poly ester-amide (PEA) nanofiber membrane was prepared by electrospinning and the surface topography of nanofiber membrane was observed by scanning electron microscope (SEM). It was found that with the increasing of spinning fluid concentration from 10% to 20%, the diameter of prepared fibers was increased from 180 nm to 305 nm. The chemical structure of PEA was detected by infrared spectrum, which showed that electrospinning had no significant effect on PEA. X-ray diffraction spectrogram and differential scanning calorimetry revealed that the crystallinity of PEA was decreased after electrospinning. Mechanical property test demonstrated that the mean breaking strength and elongation at break of PEA nanofiber membrane with (0.50±0.05) mm thickness were (1.00±0.18) MPa, and (18.20±2.86)%, respectively. MTT results showed that the endothelial cells proliferated actively on the PEA nanofiber membrane, and presented good adhesive and growth status.