Precise Detection on Cell-Cell Fusion by a Facile Molecular Beacon-Based Method.

Cell-cell fusion studies provide an experimental platform for evaluating disease progression and investigating cell infection. However, to realize sensitive and quantitative detection on cell-cell fusion is still a challenge. Herein, we report a facile molecular beacon (MB)-based method for precise detection on cell-cell fusion. By transfection of the spike protein (S protein) and enhanced green fluorescent protein (EGFP) in HEK 293 cells, the virus-mimicking fusogenic effector cells 293-S-EGFP cells were constructed to interact with target cells. Before mixing the effector cells with the target cells, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression in 293-S-EGFP cells was silenced, and the MB for GAPDH mRNA detection was delivered into the GAPDH silenced 293-S-EGFP cells. Once cell-cell fusion occurred, MB migrated from the GAPDH silenced effector cells to the target cells and hybridized with GAPDH mRNA in the target cells to induce fluorescence emission. The cell-cell fusion can be easily visualized and quantitated by fluorescence microscopy and flow cytometry. The fluorescence intensity is strongly dependent on the number of fused target cells. This MB-based method can easily identify the differences in the cell fusions for various target cells with different angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) expression levels, resulting in dramatically different fluorescence intensities in fused target cells. Our study provides a convenient and efficient quantitative detection approach to study cell-cell fusion.

Effects of occupant behavior and ventilation on exposure to respiratory droplets in the indoor environment

To quantify the risk of the transmission of respiratory infections in indoor environments, we systematically assessed exposure to talking- and breathing-generated respiratory droplets in a generic indoor environment using computational fluid dynamic (CFD) simulations. The flow field in the indoor environment was obtained with SST k-ω model and Lagrangian method was used to predict droplet trajectories, where droplet evaporation was considered. Droplets can be categorized into small droplets (initial size ≤30 μm or ≤10 μm as droplet nuclei), medium droplets (30–80 μm) and large droplets (>100 μm) according to the exposure characteristics. Droplets up to 100 μm, particular the small ones, can contribute to both short-range and long-range airborne routes. For the face-to-face talking scenario, the intake fraction and deposition fractions of droplets on the face and facial mucosa of the susceptible were up to 4.96%, 2.14%, and 0.12%, respectively, indicating inhalation is the dominant route. The exposure risk from a talking infector decreases monotonically with the interpersonal distance, while that of nasal-breathing generated droplets maintains a relatively stable level within 1.0 m. Keeping an angle of 15° or above with the expiratory flow is efficient to reduce intake fractions to <0.37% for small droplets. Adjusting the orientation from face-to-face to face-to-back can reduce exposure to small droplets by approximately 88.0% during talking and 66.2% during breathing. A higher ventilation rate can reduce the risk of exposure to small droplets but may increase the risk of transmission via medium droplets by enhancing their evaporation rate. This study would serve as a fundamental research for epidemiologist, healthcare workers and the public in the purpose of infection control.

Hemorrhagic Fever with Renal Syndrome Complicated with Rhino Mucormycosis: A Case Report.

Mucormycosis (MCR) is a rare but aggressive fungal disease. Rhino-orbito-cerebral mucormycosis is the most common clinical form of MCR infection, and sinonasal inoculation is the primary site of infection. The morbidity and mortality rates associated with MCR remain high. In this case report, we describe the successful use of amphotericin B in a 40-year-old male with hemorrhagic fever with renal syndrome (HFRS) complicated by rhinomucormycosis. This case report provides evidence for the successful treatment of HFRS.

The rationale behind the four major anti-coronavirus principles of Chinese herbal based on systems medicine

As the novel coronavirus disease 2019 (COVID-19) and its multi variants continue to rage into the second year of a global pandemic, many success stories of applying Chinese herbal medicine (CHM) to COVID-19 patients continue to emerge from China and other parts of the world. Herewith, the authors summarized those experiences from a systems medicine perspective and categorize the four major treatment principles: (1) focusing on eliminating toxins in the early stage of the disease, (2) tonifying the body against deficiency throughout the entire disease course, (3) treating affected lung and intestine simultaneously based on visceral interactions, and (4) and cooling the blood and removing blood stasis at the later stage. The rationale behind these principles is shown via a scientific interpretation. This is not only helpful in reducing the complexity of promoting the CHM applications to enhance anti-pandemic efficacy but also to ramp up the process of integrating traditional Chinese medicine with modern medical practices.

Randomized, Double-Blinded, Placebo-Controlled Phase 2 Trial of an Inactivated Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine in Healthy Adults.

BACKGROUND: We evaluated an inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine for immunogenicity and safety in adults aged 18-59 years. METHODS: In this randomized, double-blinded, controlled trial, healthy adults received a medium dose (MD) or a high dose (HD) of the vaccine at an interval of either 14 days or 28 days. Neutralizing antibody (NAb) and anti-S and anti-N antibodies were detected at different times, and adverse reactions were monitored for 28 days after full immunization. RESULTS: A total of 742 adults were enrolled in the immunogenicity and safety analysis. Among subjects in the 0, 14 procedure, the seroconversion rates of NAb in MD and HD groups were 89% and 96% with geometric mean titers (GMTs) of 23 and 30, respectively, at day 14 and 92% and 96% with GMTs of 19 and 21, respectively, at day 28 after immunization. Anti-S antibodies had GMTs of 1883 and 2370 in the MD group and 2295 and 2432 in the HD group. Anti-N antibodies had GMTs of 387 and 434 in the MD group and 342 and 380 in the HD group. Among subjects in the 0, 28 procedure, seroconversion rates for NAb at both doses were both 95% with GMTs of 19 at day 28 after immunization. Anti-S antibodies had GMTs of 937 and 929 for the MD and HD groups, and anti-N antibodies had GMTs of 570 and 494 for the MD and HD groups, respectively. No serious adverse events were observed during the study period. CONCLUSIONS: Adults vaccinated with inactivated SARS-CoV-2 vaccine had NAb as well as anti-S/N antibody and had a low rate of adverse reactions. CLINICAL TRIALS REGISTRATION: NCT04412538.

A Low-Producing Haplotype of Interleukin-6 Disrupting CTCF Binding Is Protective against Severe COVID-19.

Interleukin6 (IL-6) is a key driver of hyperinflammation in COVID-19, and its level strongly correlates with disease progression. To investigate whether variability in COVID-19 severity partially results from differential IL-6 expression, functional single-nucleotide polymorphisms (SNPs) of IL-6 were determined in Chinese COVID-19 patients with mild or severe illness. An Asian-common IL-6 haplotype defined by promoter SNP rs1800796 and intronic SNPs rs1524107 and rs2066992 correlated with COVID-19 severity. Homozygote carriers of C-T-T variant haplotype were at lower risk of developing severe symptoms (odds ratio, 0.256; 95% confidence interval, 0.088 to 0.739; P = 0.007). This protective haplotype was associated with lower levels of IL-6 and its antisense long noncoding RNA IL-6-AS1 by cis-expression quantitative trait loci analysis. The differences in expression resulted from the disturbance of stimulus-dependent bidirectional transcription of the IL-6/IL-6-AS1 locus by the polymorphisms. The protective rs2066992-T allele disrupted a conserved CTCF-binding locus at the enhancer elements of IL-6-AS1, which transcribed antisense to IL-6 and induces IL-6 expression in inflammatory responses. As a result, carriers of the protective allele had significantly reduced IL-6-AS1 expression and attenuated IL-6 induction in response to acute inflammatory stimuli and viral infection. Intriguingly, this low-producing variant that is endemic to present-day Asia was found in early humans who had inhabited mainland Asia since ∼40,000 years ago but not in other ancient humans, such as Neanderthals and Denisovans. The present study suggests that an individual's IL-6 genotype underlies COVID-19 outcome and may be used to guide IL-6 blockade therapy in Asian patients. IMPORTANCE Overproduction of cytokine interleukin-6 (IL-6) is a hallmark of severe COVID-19 and is believed to play a critical role in exacerbating the excessive inflammatory response. Polymorphisms in IL-6 account for the variability of IL-6 expression and disparities in infectious diseases, but its contribution to the clinical presentation of COVID-19 has not been reported. Here, we investigated IL-6 polymorphisms in severe and mild cases of COVID-19 in a Chinese population. The variant haplotype C-T-T, represented by rs1800796, rs1524107, and rs2066992 at the IL-6 locus, was reduced in patients with severe illness; in contrast, carriers of the wild-type haplotype G-C-G had higher risk of severe illness. Mechanistically, the protective variant haplotype lost CTCF binding at the IL-6 intron and responded poorly to inflammatory stimuli, which may protect the carriers from hyperinflammation in response to acute SARS-CoV-2 infection. These results point out the possibility that IL-6 genotypes underlie the differential viral virulence during the outbreak of COVID-19. The risk loci we identified may serve as a genetic marker to screen high-risk COVID-19 patients.

Risk assessment of public health emergencies concerned in the mainland of China, March 2021

Objective: To assess the risk of public health emergencies, both the indigenous ones and the imported ones, which might occur in the mainland of China in March 2021.

Epidemiological characteristics of COVID-19 in Hainan Province, China

The epidemiology characteristics of 2019 novel coronavirus diseases (COVID-19) cases in Hainan were collected and analyzed for providing next stage control and prevention strategy in next stage. Spatial and temporal distribution, population characteristic, cluster, the interval between onset, visiting clinic, admitted were analyzed. Local cases and severe cases were also included in the analysis. Result showed that a total of 168 confirmed cases, including 36 severe cases and 5 fatal cases were reported. Cases were mainly distributed in Haikou, Sanya etc tourism cities and counties. The first case occurred in Jan 13th and the epidemic peak occurred in Jan 24th. Since Feb 6th, onset of illness has declined. The male-to-female ratio was 0.9:1. The median age was 51 years. Cases older than 50 years accounted for 54.8%. Retirees accounted for 36.9%, which was highest in all cases. Since Feb, the proportion of local cases rose dramatically. The period from onset to visiting clinic (OTV), from first visiting clinic to diagnosis (VTF), from onset to diagnosis (OTD) and from onset to be admitted (OTA) was longer in local cases than imported cases. Median age and the percentage of underlying diseases of severe/extreme cases were higher than mild/ordinary cases. OTV of severe/extreme cases was longer than mild/ordinary cases, while for VTF, the former was shorter than latter. The epidemic was divided into three stages. Most of cases in the first stage were imported cases, while in the second stage most of cases were local cases. There were few cases in the third stages. We should strengthen personal protection and health monitoring for people in service industry, isolate the close contacts, and carry out publicity and education to raise the awareness of medical treatment for people, especially for old people. Clinical doctors should monitor the state of the patients older than 60 years and with underlying diseases. We should step up epidemic monitoring prevention and control measure for people return from holiday and immigrant to consolidate the effects of prevention and control work.

Clinical features and the maternal and neonatal outcomes of pregnant women with coronavirus disease 2019 (preprint)

BACKGROUND There is little information about the coronavirus disease 2019 (Covid-19) during pregnancy. This study aimed to determine the clinical features and the maternal and neonatal outcomes of pregnant women with Covid-19. METHODS In this retrospective analysis from five hospitals, we included pregnant women with Covid-19 from January 1 to February 20, 2020. The primary composite endpoints were admission to an intensive care unit (ICU), the use of mechanical ventilation, or death. Secondary endpoints included the clinical severity of Covid-19, neonatal mortality, admission to neonatal intensive care unit (NICU), and the incidence of acute respiratory distress syndrome (ARDS) of pregnant women and newborns. RESULTS Thirty-three pregnant women with Covid-19 and 28 newborns were identified. One (3%) pregnant woman needed the use of mechanical ventilation. No pregnant women admitted to the ICU. There were no moralities among pregnant women or newborns. The percentages of pregnant women with mild, moderate, and severe symptoms were 13 (39.4%),19(57.6%), and 1(3%). One (3.6%) newborn developed ARDS and was admitted to the NICU. The rate of perinatal transmission of SARS-CoV-2 was 3.6%. CONCLUSIONS This report suggests that pregnant women are not at increased risk for severe illness or mortality with Covid-19 compared with the general population. The SARS-CoV-2 infection during pregnancy might not be associated with as adverse obstetrical and neonatal outcomes that are seen with the severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) infection during pregnancy. (Funded by the National Key Research and Development Program.)