Emerging triple-reassortant influenza C virus with household-associated infection during an influenza A(H3N2) outbreak, China, 2022.

Recent research have shown that influenza C virus (ICV) has a possible higher clinical impact than previously thought. But knowledge about ICV is limited compared with influenza A and B viruses, due to poor systematic surveillance and inability to propagate. Herein, a case infected with triple reassortant ICV was identified during an influenza A(H3N2) outbreak, which was the first report of ICV infection in mainland China. Phylogenetic analysis showed that this ICV was triple reassortant. Serological evidence revealed that the index case might be related to family-clustering infection. Therefore, it is essential to heighten surveillance for the prevalence and variation of ICV in China, during the COVID-19 pandemic.

Low infectious risk of re-positive COVID-19 patients: a single-center study.

OBJECTIVE: The aim of this study was to investigate the infectiousness of re-positive coronavirus disease 2019 (COVID-19) patients. METHODS: All nucleic acid testing (NAT) was performed using throat swabs, nasopharyngeal swabs, and anal swabs, which were tested by Fluorescent quantitative realtime PCR. Re-positive cases were defined as a discharged patient who re-tested positive by NAT. Micro-neutralization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was performed based on the methods for severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) viruses. IgM and IgG against the N protein of SARS-CoV-2 were determined by ELISA. RESULTS: A total 255 (16.04%) of 1590 COVID-19 patients were re-positive. The re-positive cases were more likely to occur in patients in the 20-39 years age group and in patients with disease of moderate severity. Quantitative PCR showed that cycle threshold (Ct) values and viral loads were both far lower than in the hospitalized COVID-19 patients. The viral load in re-positive cases was very low. Viral culture of the samples from re-positive patients showed no cytopathic effect, and NAT of the culture medium of viral cultures all exhibited negative results. CONCLUSION: The viral load in re-positive cases was very low; patients were not infectious and the risk of human-to-human transmission was extremely low. Discharged COVID-19 patients should undergo home health management for 3 weeks.

First isolation and identification of SARS-CoV-2 in Guangdong Province, China

In January 2020, Guangdong Province, China imported several suspected cases with SARS-CoV-2 from Wuhan City, Hubei Province. China, which were detected as SARS-CoV-2 positive in laboratory. To further understand the SARS-CoV-2 virulence, as well as drug development and epidemic prevention and control needs, we established a SARS-CoV-2 isolation procedure. Vero-E6 cells were infected with the positive bronchoalveolar-lavage sample. The cells were monitored daily for cytopathic effects using light microscopy. The presence of viral nucleic acid in the supernatant was detected by RT-PCR. RNA extracted from culture supernatants were used as a template to clone and sequence the genome. We used Illumina sequencing to characterize the virus genome and results showed that the isolated virus was SARS-CoV-2.

Ethical review of off-label drugs during the COVID-19 pandemic.

High-quality scientific research is very important in attempting to effectively control the coronavirus disease 2019 (COVID-19) pandemic and ensure people's health and safety. Chloroquine (CQ) and hydroxychloroquine (HCQ) have received much attention. This article comprehensively investigates the ethical review of off-label CQ and HCQ research during the COVID-19 pandemic with regard to strictly abiding by review standards, improving review efficiency, ensuring the rights and interests of subjects and that ethics committees conduct independent reviews, and achieving full ethics supervision of research conducted during an emergency. Research must be both rigorous and prudent to ensure the best outcome, with the maximization of benefits as the core principle. Standardization of the application, implementation and ethical review processes are needed to prevent unnecessary risk.

Transcriptional regulation and small compound targeting of ACE2 in lung epithelial cells.

Angiotensin-converting enzyme 2 (ACE2) is the receptor of COVID-19 pathogen SARS-CoV-2, but the transcription factors (TFs) that regulate the expression of the gene encoding ACE2 (ACE2) have not been systematically dissected. In this study we evaluated TFs that control ACE2 expression, and screened for small molecule compounds that could modulate ACE2 expression to block SARS-CoV-2 from entry into lung epithelial cells. By searching the online datasets we found that 24 TFs might be ACE2 regulators with signal transducer and activator of transcription 3 (Stat3) as the most significant one. In human normal lung tissues, the expression of ACE2 was positively correlated with phosphorylated Stat3 (p-Stat3). We demonstrated that Stat3 bound ACE2 promoter, and controlled its expression in 16HBE cells stimulated with interleukin 6 (IL-6). To screen for medicinal compounds that could modulate ACE2 expression, we conducted luciferase assay using HLF cells transfected with ACE2 promoter-luciferase constructs. Among the 64 compounds tested, 6-O-angeloylplenolin (6-OAP), a sesquiterpene lactone in Chinese medicinal herb Centipeda minima (CM), represented the most potent ACE2 repressor. 6-OAP (2.5 µM) inhibited the interaction between Stat3 protein and ACE2 promoter, thus suppressed ACE2 transcription. 6-OAP (1.25-5 µM) and its parental medicinal herb CM (0.125%-0.5%) dose-dependently downregulated ACE2 in 16HBE and Beas-2B cells; similar results were observed in the lung tissues of mice following administration of 6-OAP or CM for one month. In addition, 6-OAP/CM dose-dependently reduced IL-6 production and downregulated chemokines including CXCL13 and CX3CL1 in 16HBE cells. Moreover, we found that 6-OAP/CM inhibited the entry of SARS-CoV-2 S protein pseudovirus into target cells. These results suggest that 6-OAP/CM are ACE2 inhibitors that may potentially protect lung epithelial cells from SARS-CoV-2 infection.

Perspectives of research ethics committee members on human challenge studies in the development of vaccines against COVID-19: a mixed methods study.

BACKGROUND: Vaccines are considered the most effective protection against the coronavirus disease 2019 (COVID-19). Human Challenge Studies can help to shorten the development process of vaccines. The reviewers' opinions from research ethics committees (REC) play an essential gate-keeping role in determining whether a clinical trial can be conducted or not. METHODS: A convergent mixed-methods study was conducted in a leading general hospital in China. A total of 58 REC members from the institution were invited to participate in an online questionnaire survey. According to the result of the quantitative survey, 15 of these REC members were purposefully selected to participate in qualitative interviews further. Quantitative data were analyzed using descriptive statistical techniques, and thematic analysis was used to analyze the qualitative data. Findings from the quantitative and qualitative analyses were synthesized to deeply illustrate the attitudes, views, and suggestions of REC members on human challenge studies to develop COVID-19 vaccination. RESULTS: The response rate of the online questionnaire was 62% (36/58), and 15 of the respondents were interviewed. All participants deemed that the human challenge study should provide compensation to its participants and that sufficiently informed consent is necessary. The human challenge study was disagreed with by 38.9% of participants. The key points of concern raised were representativeness and fairness of participant selection, benefit, and risk, vulnerable groups, compensation to participants, informed consent, and general view on human challenge studies. CONCLUSIONS: Human challenge studies helped accelerate the development of vaccines for disease control to a certain extent, but the bottom line of medical ethics should not have been broken. At any time, the rights and interests of research participants should come first.

Genomic Evolution and Variation of SARS-CoV-2 in the Early Phase of COVID-19 Pandemic in Guangdong Province, China.

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) with unknown origin spread rapidly to 222 countries, areas or territories. To investigate the genomic evolution and variation in the early phase of COVID-19 pandemic in Guangdong, 60 specimens of SARS-CoV-2 were used to perform whole genome sequencing, and genomics, amino acid variation and Spike protein structure modeling analyses. Phylogenetic analysis suggested that the early variation in the SARS-CoV-2 genome was still intra-species, with no evolution to other coronaviruses. There were one to seven nucleotide variations (SNVs) in each genome and all SNVs were distributed in various fragments of the genome. The Spike protein bound with human receptor, an amino acid salt bridge and a potential furin cleavage site were found in the SARS-CoV-2 using molecular modeling. Our study clarified the characteristics of SARS-CoV-2 genomic evolution, variation and Spike protein structure in the early phase of local cases in Guangdong, which provided reference for generating prevention and control strategies and tracing the source of new outbreaks.

Molecular modeling evaluation of the binding effect of five protease inhibitors to COVID-19 main protease.

Coronavirus disease 2019 (COVID-19) has caused more than 840,000 deaths as of 31 August 2020 in the whole world. The COVID-19 main protease (Mpro) has been validated as an attractive target for drug design. In this work, the binding mechanisms of five protease inhibitors (e.g., danoprevir, darunavir, ASC09, lopinavir and ritonavir) to COVID-19 Mpro were investigated. Based on the docking score, five protease inhibitors structures were selected for further evaluation. It is found that most of the selected drug molecules bind stably to the COVID-19 Mpro from the molecular dynamics simulation. Moreover, the MM/PBSA free energy calculations suggest that lopinavir with positive charge might be most active against COVID-19 Mpro.

High-coverage SARS-CoV-2 genome sequences acquired by target capture sequencing.

In this study, we designed a set of SARS-CoV-2 enrichment probes to increase the capacity for sequence-based virus detection and obtain the comprehensive genome sequence at the same time. This universal SARS-CoV-2 enrichment probe set contains 502 120 nt single-stranded DNA biotin-labeled probes designed based on all available SARS-CoV-2 viral sequences and it can be used to enrich for SARS-CoV-2 sequences without prior knowledge of type or subtype. Following the CDC health and safety guidelines, marked enrichment was demonstrated in a virus strain sample from cell culture, three nasopharyngeal swab samples (cycle threshold [Ct ] values: 32.36, 36.72, and 38.44) from patients diagnosed with COVID-19 (positive control) and four throat swab samples from patients without COVID-19 (negative controls), respectively. Moreover, based on these high-quality sequences, we discuss the heterozygosity and viral expression during coronavirus replication and its phylogenetic relationship with other selected high-quality samples from the Genome Variation Map. Therefore, this universal SARS-CoV-2 enrichment probe system can capture and enrich SARS-CoV-2 viral sequences selectively and effectively in different samples, especially clinical swab samples with a relatively low concentration of viral particles.