Identification of potential target endoribonuclease NSP15 inhibitors of SARS-COV-2 from natural products through high-throughput virtual screening and molecular dynamics simulation.

SARS-CoV-2 wreaks havoc around the world, triggering the COVID-19 pandemic. It has been confirmed that the endoribonuclease NSP15 is crucial to the viral replication, and thus identified as a potential drug target against COVID-19. The NSP15 protein was used as the target to conduct high-throughput virtual screening on 30,926 natural products from the NPASS database to identify potential NSP15 inhibitors. And 100 ns molecular dynamics simulations were performed on the NSP15 and NSP15-NPC198199 system. In all, 10 natural products with high docking scores with NSP15 protein were obtained, among which compound NPC198199 scored the highest. The analysis of the binding mode between NPC198199 and NSP15 found that NPC198199 would form H-bond interactions with multiple key residues at the catalytic site. Subsequently, a series of post-dynamics simulation analyses (including RMSD, RMSF, PCA, DCCM, RIN, binding free energy, and H-bond occupancy) were performed to further explore inhibitory mechanism of compound NPC198199 on NSP15 protein at the molecular level. The research strongly indicates that the 10 natural compounds screened can be used as potential inhibitors of NSP15, and provides valuable information for the subsequent drug discovery of anti-SARS-CoV-2. PRACTICAL APPLICATIONS: Natural products play an important role in the treatment of many difficult diseases. In this study, high-throughput virtual screening technology was used to screen the natural product database to obtain potential inhibitors against endoribonuclease NSP15. The binding mechanism between natural products and NSP15 was investigated at the molecular level by molecular dynamics technology so that it is expected to become candidate drugs for the treatment of SARS-CoV-2. We hope that our research can provide new clue to combat COVID-19 and overcome the epidemic situation as soon as possible.

A qualitative study of zoonotic risk factors among rural communities in southern China.

BACKGROUND: Strategies are urgently needed to mitigate the risk of zoonotic disease emergence in southern China, where pathogens with zoonotic potential are known to circulate in wild animal populations. However, the risk factors leading to emergence are poorly understood, which presents a challenge in developing appropriate mitigation strategies for local communities. METHODS: Residents in rural communities of Yunnan, Guangxi and Guangdong provinces were recruited and enrolled in this study. Data were collected through ethnographic interviews and field observations, and thematically coded and analysed to identify both risk and protective factors for zoonotic disease emergence at the individual, community and policy levels. RESULTS: Eighty-eight ethnographic interviews and 55 field observations were conducted at nine selected sites. Frequent human-animal interactions and low levels of environmental biosecurity in local communities were identified as risks for zoonotic disease emergence. Policies and programmes existing in the communities provide opportunities for zoonotic risk mitigation. CONCLUSIONS: This study explored the relationship among zoonotic risk and human behaviour, environment and policies in rural communities in southern China. It identifies key behavioural risk factors that can be targeted for development of tailored risk-mitigation strategies to reduce the threat of novel zoonoses.

Effects of Chinese Medicine on Symptoms, Syndrome Evolution, and Lung Inflammation Absorption in COVID-19 Convalescent Patients during 84-Day Follow-up after Hospital Discharge: A Prospective Cohort and Nested Case-Control Study.

OBJECTIVE: To observe the changes of symptoms, Chinese medicine (CM) syndrome, and lung inflammation absorption during convalescence in patients with coronavirus disease 2019 (COVID-19) who had not totally recovered after hospital discharge and whether CM could promote the improvement process. METHODS: This study was designed as a prospective cohort and nested case-control study. A total of 96 eligible patients with COVID-19 in convalescence were enrolled from Beijing Youan Hospital and Beijing Huimin Hospital and followed up from the hospital discharged day. Patients were divided into the CM (64 cases) and the control groups (32 cases) based on the treatment with or without CM and followed up at 14, 28, 56, and 84 days after discharge. In the CM group, patients received the 28-day CM treatment according to two types of CM syndrome. Improvements in clinical symptoms, CM syndrome, and absorption of lung inflammation were observed. RESULTS: All the 96 patients completed the 84-day follow-up from January 21 to March 28, 2020. By the 84th day of follow-up, respiratory symptoms were less than 5%. There was no significant difference in the improvement rates of symptoms, including fatigue, sputum, cough, dry throat, thirst, and upset, between the two groups (P>0.05). Totally 82 patients (85.42%) showed complete lung inflammation absorption at the 84-day follow-up. On day 14, the CM group had a significantly higher absorption rate than the control group (P<0.05) and the relative risk of absorption for CM vs. control group was 3.029 (95% confidence interval: 1.026-8.940). The proportions of CM syndrome types changed with time prolonging: the proportion of the pathogen residue syndrome gradually decreased, and the proportion of both qi and yin deficiency syndrome gradually increased. CONCLUSIONS: Patients with COVID-19 in convalescence had symptoms and lung inflammation after hospital discharge and recovered with time prolonging. CM could improve lung inflammation for early recovery. The types of CM syndrome can be transformed with time prolonging. (Registration No. ChiCTR2000029430).