GPS/BDS signal analysis and precise orbit determination of the inclined geosynchronous orbit satellite LT4A (preprint)

The LT4A satellite is the world's first IGSO satellite capable of receiving GPS and BDS signals. It is also the world's first SAR satellite in high orbit. Based on the received GNSS data, the data availability and measurement quality were first analyzed, and then the accuracy of the 30-h and 72-h arc length orbit determination results were verified using the orbit overlap method and the laser ranging verification method. According to the data analysis, the onboard receiver of the LT4A satellite can receive an average of 3.9 GPS satellites and 4.0 BDS satellites in a single epoch. The PDOPs of GPS observations, BDS observations, and combined GPS + BDS observations are 21.66, 25.96, and 15.81, and the number of epochs with more than four satellites is 32.6%, 37.6%, and 98.5% of the total epochs. The cycle slip ratios of the GPS and BDS observations are 6.3% and 28.9%, the pseudo-range noise is 1.75 m and 0.95 m, the carrier phase noise is 0.46 mm and 0.35 mm, and the average CNR are 44.6 dB-Hz and 46.9 dB-Hz, respectively. When only GPS observations, only BDS observations, and combined GPS + BDS observations are used, the average RMS of the overlapping results for the 30-h arcs is 4.091 m, 4.319 m, and 2.274 m, and the laser range verification results are 0.994 m, 0.978 m, and 0.277 m. The average RMS of the overlapping results for the 72-h arcs is 3.242 m, 3.199 m, and 1.807 m, and the laser ranging verification results are 0.527 m, 0.687 m, and 0.356 m. The onboard real-time orbit was used for observations to determine the orbit, resulting in a 95.4% improvement in the RMS of the original real-time orbit.

Interruption of influenza transmission under public health emergency response based on real-world data, Beijing. (preprint)

Background: To estimate effect of COVID-19 control measures taken to mitigate community transmission in many regions, we analyzed data based on influenza surveillance system in Beijing from week 27th, 2014 to week 26th, 2020. Methods. We collected weekly number of influenza-like illness (ILI), weekly positive proportion of ILI and weekly ILI proportion in outpatients and the date of COVID-19 measures. We compared influenza activity indicators of influenza season 2019/2020 with preceding five seasons and built two ARIMAX models to estimate the effective of COVID-19 measures. Results. Compared with preceding five influenza seasons, ILIs, positive proportion of ILI, and duration of influenza epidemic period decreased from 13% to 54%, especially, the number of weeks from the peak to the end of influenza epidemic period, decreased from 12 to one. After natural decline considered, weekly ILIs decreased by 48.6% and weekly positive proportion dropped 15% in the second week after emergency response declared, and finally COVID-19 measures reduced 83%. Conclusions. We conclude public health emergency response can interrupt the transmission of influenza and other respiratory infectious diseases markedly. Keyword. COVID-19 control measures; influenza; ARIMAX

Changes in Spectrum of Respiratory Pathogen Infections and Disease Severity Among Children in Hohhot: Impact of COVID-19 Prevention Measures (preprint)

Background Acute respiratory infections (ARIs) are caused by various pathogens, and the outbreak of the novel coronavirus has led to changes in the patterns of respiratory pathogen infections. Through long-term study of respiratory tract infection data in children from Hohhot, significant differences in the spectrum of respiratory pathogen infections, disease severity, and seasonal patterns have been discovered between 2022 and 2023.Methods Throat swabs were collected from 605 children with ARIs at the First Hospital of Hohhot, and pathogen detection was performed using microarray technology. Blood biomarkers, symptoms, and clinical diagnoses were evaluated.Results The study found that 56.03% of the patients were male, with an average age of 3.45 years. Pathogen dynamics revealed that SARS-CoV-2 was the most prevalent infection, accounting for 262 cases. It persisted from October 2022 to January 2023 and then disappeared. Influenza A virus (IAV) cases peaked in March 2023. Respiratory syncytial virus (RSV), Influenza B virus (IBV), Parainfluenza virus (PIV), Mycoplasma pneumoniae (M. pneumoniae), Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Group A streptococcus (GAS) were not detected after December 2022. The proportion of mixed infections was 41.94% among SARS-CoV-2 patients, while other pathogens had mixed infection rates exceeding 57.14%. Before December 2022, the mean value of white blood cell (WBC) count for Streptococcus pneumoniae (S. pneumoniae), Haemophilus influenzae (H. influenzae), Epstein-Barr virus (EBV), and Cytomegalovirus (CMV) was 8.83*10^9/L, C-reactive protein (CRP) was 18.36 mg/L, and procalcitonin (PCT) was 1.11 ng /ml. After December 2022, these values decreased to 5.5*10^9/L, 6.33 mg/L, and 0.24 ng /ml, respectively. Similarly, the proportion of patients with cough, difficulty breathing, and running nose, as well as the diagnosis of lower respiratory tract infections, decreased in December 2022. However, the situation was different for SARS-CoV-2 infections.Conclusions Strict SARS-CoV-2 policies reduced the infection risk for S. pneumoniae, H. influenzae, EBV, and other pathogens before November 2022. However, patient symptoms worsened compared to after November 2022, possibly due to an excessive focus on SARS-CoV-2, neglecting other diseases, and reduced population immunity to respiratory infections.

Dicoumarol is an effective post-exposure prophylactic for SARS-CoV-2 Omicron infection in human airway epithelium.

Repurposing existing drugs to inhibit SARS-CoV-2 infection in airway epithelial cells (AECs) is a quick way to find novel treatments for COVID-19. Computational screening has found dicoumarol (DCM), a natural anticoagulant, to be a potential SARS-CoV-2 inhibitor, but its inhibitory effects and possible working mechanisms remain unknown. Using air-liquid interface culture of primary human AECs, we demonstrated that DCM has potent antiviral activity against the infection of multiple Omicron variants (including BA.1, BQ.1 and XBB.1). Time-of-addition and drug withdrawal assays revealed that early treatment (continuously incubated after viral absorption) of DCM could markedly inhibit Omicron replication in AECs, but DCM did not affect the absorption, exocytosis and spread of viruses or directly eliminate viruses. Mechanistically, we performed single-cell sequencing analysis (a database of 77,969 cells from different airway locations from 10 healthy volunteers) and immunofluorescence staining, and showed that the expression of NAD(P)H quinone oxidoreductase 1 (NQO1), one of the known DCM targets, was predominantly localised in ciliated AECs. We further found that the NQO1 expression level was positively correlated with both the disease severity of COVID-19 patients and virus copy levels in cultured AECs. In addition, DCM treatment downregulated NQO1 expression and disrupted signalling pathways associated with SARS-CoV-2 disease outcomes (e.g., Endocytosis and COVID-19 signalling pathways) in cultured AECs. Collectively, we demonstrated that DCM is an effective post-exposure prophylactic for SARS-CoV-2 infection in the human AECs, and these findings could help physicians formulate novel treatment strategies for COVID-19.

Does airway pressure release ventilation offer new hope for treating acute respiratory distress syndrome?☆

Mechanical ventilation (MV) is an essential life support method for patients with acute respiratory distress syndrome (ARDS), which is one of the most common critical illnesses with high mortality in the intensive care unit (ICU). A lung-protective ventilation strategy based on low tidal volume (LTV) has been recommended since a few years;however, as this did not result in a significant decrease of ARDS-related mortality, a more optimal ventilation mode was required. Airway pressure release ventilation (APRV) is an old method defined as a continuous positive airway pressure (CPAP) with a brief intermittent release phase based on the open lung concept;it also perfectly fits the ARDS treatment principle. Despite this, APRV has not been widely used in the past, rather only as a rescue measure for ARDS patients who are difficult to oxygenate. Over recent years, with an increased understanding of the pathophysiology of ARDS, APRV has been reproposed to improve patient prognosis. Nevertheless, this mode is still not routinely used in ARDS patients given its vague definition and complexity. Consequently, in this paper, we summarize the studies that used APRV in ARDS, including adults, children, and animals, to illustrate the settings of parameters, effectiveness in the population, safety (especially in children), incidence, and mechanism of ventilator-induced lung injury (VILI) and effects on extrapulmonary organs. Finally, we found that APRV is likely associated with improvement in ARDS outcomes, and does not increase injury to the lungs and other organs, thereby indicating that personalized APRV settings may be the new hope for ARDS treatment.

The influence of college students' academic stressors on mental health during COVID-19: The mediating effect of social support, social well-being, and self-identity

COVID-19 caused harmful mental consequences to the public, and mental health problems were very common among college students during the outbreak of COVID-19. Academic stressors were the main stress for college students, and social support, social well-being, and self-identity were widely known as protective factors for mental health. Therefore, the study aimed to investigate the influence of academic stressors on mental health and the mediating effect of social support, social well-being, and self-identity among college students during the outbreak of COVID-19. With 900 college students as subjects, using the college students' academic stressors questionnaire, social support questionnaire, social well-being scale, self-identity scale, and depression anxiety stress scales (DASS-21), the results showed that: (1) academic stressors had a significantly negative correlation with social support, social well-being, and self-identity while having a significantly positive correlation with mental health;(2) academic stressors could positively predict mental health;(3) this effect was mediated by social support, social well-being, and self-identity;(4) work stressor was an important stressor during COVID-19, and had the same role as academic stressors in the structural equation model. The results of this study suggested that adjusting the academic stressors or work stressors of college students and enhancing social support could improve social well-being and self-identity, and might effectively protect their mental health under the COVID-19 pandemic environment.

Establishment of ELISA for detecting porcine epidemic diarrhea virus specific SIgA in mucus

The aim of this study is to establish an indirect ELISA technique for detecting the SIgA antibody against porcine epidemic diarrhea virus (PEDV) to evaluate its mucosal immunity. Firstly, the S1D gene (534-789 aa) of PEDV was cloned into the pET-28a(+) vector, and induced in Escherichia coli BL21 (DE3) by IPTG, the product of which was in the form of inclusion bodies. According to Western-blot, the target protein S1D with antigenic activity was 32 ku in molecular weight and could be well detected. Then, the S1D protein was denatured by 8 mol/L urea, purified and gradient as the coating antigen to establish an indirect ELISA for detecting the PEDV specific SIgA antibody in nasal or oral mucus by optimizing conditions. And the optimal antigen coating concentration of ELISA was 2 micro g mL, the working concentrations of nasal mucus was 1:1 and the optimal blocking solution was 50 g/L skimmed milk, while the working concentrations and optimal blocking solution were 1:2 and 30 g/L BSA in oral mucus, the working concentrations of the enzyme-labeled antibody was 1:2 000 in nasal and oral mucus. Finally, 84 samples of oral and nasal mucus from immunized pigs were detected by S1D of ELISA, and the coincidence rate could reach 95.2% compared with purified PEDV of ELISA. In conclusion, the indirect ELISA established in this study provided a quick, simple, sensitive, and specific method to detect PEDV specific SigA for evaluating the level of PEDV mucosal immunity.

Computational tools for aptamer identification and optimization

Aptamers are single-stranded DNA or RNA oligonucleotides that can selectively bind to a specific target. They are generally obtained by SELEX, but the procedure is challenging and time-consuming. Moreover, the identified aptamers tend to be insufficient in stability, specificity, and affinity. Thus, only a handful of aptamers have entered the practical use stage. Recently, computational approaches have demonstrated a significant capacity to assist in the discovery of high-performance aptamers. This review discusses the advances achieved in several aspects of computational tools in this field, as well as the new progress in machine learning and deep learning, which are used in aptamer identification and optimization. To illustrate these computationally aided processes, aptamers selection against SARS-CoV-2 is discussed in detail as a case study. We hope that this review will aid and motivate researchers to develop and utilize more computational techniques to discover ideal aptamers effectively.

Frailty and risks of all-cause and cause-specific death in community-dwelling adults: a systematic review and meta-analysis.

BACKGROUND: The associations of frailty with all-cause and cause-specific mortality remain unclear. Therefore, we performed this meta-analysis to fill this gap. METHODS: We searched the PubMed and Embase databases through June 2022. Prospective cohort studies or clinical trials examining frailty were evaluated, and the multiple adjusted risk estimates of all-cause and cause-specific mortality, such as death from cardiovascular disease (CVD), cancer, respiratory illness, dementia, infection, and coronavirus disease 2019 (COVID-19), were included. A random effects model was used to calculate the summary hazard ratio (HR). RESULTS: Fifty-eight studies were included for the qualitative systematic review, of which fifty-six studies were eligible for the quantitative meta-analysis, and the studies included a total of 1,852,951 individuals and more than 145,276 deaths. Compared with healthy adults, frail adults had a significantly higher risk of mortality from all causes (HR 2.40; 95% CI 2.17-2.65), CVD (HR 2.64; 95% CI 2.20-3.17), respiratory illness (HR 4.91; 95% CI 2.97-8.12), and cancer (HR 1.97; 95% CI 1.50-2.57). Similar results were found for the association between prefrail adults and mortality risk. In addition, based on the studies that have reported the HRs of the mortality risk per 0.1 and per 0.01 increase in the frailty index, we obtained consistent results. CONCLUSIONS: The present study demonstrated that frailty was not only significantly related to an increased risk of all-cause mortality but was also a strong predictor of cause-specific mortality from CVD, cancer, and respiratory illness in community-dwelling adults. More studies are warranted to clarify the relationship between frailty and cause-specific mortality from dementia, infection, and COVID-19. TRIAL REGISTRATION: PROSPERO (CRD42021276021).

Tansmembrane TNF-α as a novel biomarker for the diagnosis of cytokine storm in a mouse model of multiple organ failure (preprint)

A cytokine storm(CS) is an out-of-control inflammatory response closely associated with the progression of diseases, such as multiple organ failure(MOF), severe sepsis, and severe or critical COVID-19. However, there is currently a lack of reliable diagnostic markers to distinguish CS from normal inflammatory responses. Tumor necrosis factor-α (TNF-α) includes transmembrane TNF-α (tmTNF-α) and secreted TNF-α (sTNF-α). The MOF mouse model in this study showed that the tmTNF-α expression changes in the neutrophils differed from the serum TNF-α and serum IL-4, IL-6, IL-10, and IL-18 and it was the tmTNF-α, instead of serum TNF-α, IL-4, IL-6, IL-10, and IL-18, that reflected the liver and kidney tissue damage and increased with the aggravation of these injuries. Analysis of the ROC results showed that tmTNF-α effectively distinguished between inflammatory response and CS and efficiently differentiated between surviving and dead mice. It also significantly improved the diagnostic value of the traditional CRP marker for CS. These results indicated that tmTNF-α expressed in the neutrophil could be used to diagnose CS in MOF mice, providing an experimental basis to further develop tmTNF-α for diagnosing CS patients.

Quantitative Ground Risk Assessment for Urban Logistical Unmanned Aerial Vehicle (UAV) Based on Bayesian Network

The Unmanned Aerial Vehicle (UAV) has been used for the delivery of medical supplies in urban logistical distribution, due to its ability to reduce human contact during the global fight against COVID-19. However, due to the reliability of the UAV system and the complex and changeable operation scene and population distribution in the urban environment, a few ground-impact accidents have occurred and generated enormous risks to ground personnel. In order to reduce the risk of UAV ground-impact accidents in the urban logistical scene, failure causal factors, and failure modes were classified and summarized in the process of UAV operation based on the accumulated operation data of more than 20,000 flight hours. The risk assessment model based on the Bayesian network was built. According to the established network and the probability of failure causal factors, the probabilities of ground impact accidents and intermediate events under different working conditions were calculated, respectively. The posterior probability was carried out based on the network topology to deduce the main failure inducement of the accidents. Mitigation measures were established to achieve the equivalent safety level of manned aviation, aiming at the main causes of accidents. The results show that the safety risk of the UAV was reduced to 3.84 × 10−8 under the action of risk-mitigation measures.

7Ps theory of service marketing innovation: a survival strategy for hotel sector post COVID-19 in China. (Special Issue: Hospitality and tourism industry survival: critical perspective on industry recovery and adaptation.)

Significant impact of COVID-19;reducing demand from hotels, shifting customer needs, and increasing costs of prevention, have all intensified competition in the hotel industry. China, as one of the best countries in the world in terms of COVID-19 prevention and control, has taken the lead in the post-COVID-19 era. The service marketing strategy has become a key element in the full range of corporate services to seize the opportunities by enhancing the culture of corporate personnel, personalization of products and construction of environmental facilities. This paper examines the current marketing situation and problems in the hotel industry by conducting a SWOT analysis, PEST analysis and local market segmentation analysis using China as an example. It then applies the 7P theory of service marketing to make recommendations from seven aspects: product, price, channel, promotion, personnel management, tangible display and service process. The 7PS practices are of great practical importance to the long-term development of enterprises and helps hotel brands to develop better. Guiding enterprises to explore its application on a theoretical basis, while testing its effects would be good for further research.

Inspiration for COVID-19 Treatment: Network Analysis and Experimental Validation of Baicalin for Cytokine Storm

Background: Cytokine storm (CS) is a systemic inflammatory syndrome and a major cause of multi-organ failure and even death in COVID-19 patients. With the increasing number of COVID-19 patients, there is an urgent need to develop effective therapeutic strategies for CS. Baicalin is an anti-inflammatory and antiviral traditional Chinese medicine. In the present study, we aimed to evaluate the therapeutic mechanism of baicalin against CS through network analysis and experimental validation, and to detect key targets of CS that may bind closely to baicalin through molecular docking. Method: Access to potential targets of baicalin and CS in public databases. We constructed the protein-protein interaction (PPI) network of baicalin and CS by Cytoscape 9.0 software and performed network topology analysis of the potential targets. Then, the hub target was identified by molecular docking technique and validated in the CS model. Finally, GO and KEGG pathway functional enrichment analysis of common targets were confirmed using R language, and the location of overlapping targets in key pathways was queried via KEGG Mapper. Result: A total of 86 overlapping targets of baicalin and CS were identified, among which MAPK14, IL2, FGF2, CASP3, PTGS2, PIK3CA, EGFR, and TNF were the core targets. Moreover, it was found that baicalin bound most closely to TNF through molecular docking, and demonstrated that baicalin can effectively inhibit the elevation of TNF-α in vitro and in vivo. Furthermore, bioenrichment analysis revealed that the TNF signaling pathway and IL-17 signaling pathway may be potential key pathways for baicalin to treat CS. Conclusion: Based on this study, baicalin was identified as a potential drug for the alleviation of CS, and the possible key targets and pathways of baicalin for the treatment of CS were elucidated to reveal the main pharmacological mechanisms.

Angiotensin-converting enzyme 2 in peripheral lung club cells modulates the susceptibility to SARS-CoV-2 in chronic obstructive pulmonary disease.

Accumulating evidence has confirmed that chronic obstructive pulmonary disease (COPD) is a risk factor for development of severe pathological changes in the peripheral lungs of patients with COVID-19. However, the underlying molecular mechanisms remain unclear. Because bronchiolar club cells are crucial for maintaining small airway homeostasis, we sought to explore whether the altered susceptibility to SARS-CoV-2 infection of the club cells might have contributed to the severe COVID-19 pneumonia in COPD patients. Our investigation on the quantity and distribution patterns of angiotensin-converting enzyme 2 (ACE2) in airway epithelium via immunofluorescence staining revealed that the mean fluorescence intensity of the ACE2-positive epithelial cells was significantly higher in club cells than those in other epithelial cells (including ciliated cells, basal cells, goblet cells, neuroendocrine cells, and alveolar type 2 cells). Compared with nonsmokers, the median percentage of club cells in bronchiolar epithelium and ACE2-positive club cells was significantly higher in COPD patients. In vitro, SARS-CoV-2 infection (at a multiplicity of infection of 1.0) of primary small airway epithelial cells, cultured on air-liquid interface, confirmed a higher percentage of infected ACE2-positive club cells in COPD patients than in nonsmokers. Our findings have indicated the role of club cells in modulating the pathogenesis of SARS-CoV-2-related severe pneumonia and the poor clinical outcomes, which may help physicians to formulate a novel therapeutic strategy for COVID-19 patients with coexisting COPD.

Structural and functional characterizations of altered infectivity and immune evasion of SARS-CoV-2 Omicron variant (preprint)

The SARS-CoV-2 Omicron with increased fitness is spreading rapidly worldwide. Analysis of cryo-EM structures of the Spike (S) from Omicron reveals amino acid substitutions forging new interactions that stably maintain an active conformation for receptor recognition. The relatively more compact domain organization confers improved stability and enhances attachment but compromises the efficiency of viral fusion step. Alterations in local conformation, charge and hydrophobic microenvironments underpin the modulation of the epitopes such that they are not recognized by most NTD- and RBD-antibodies, facilitating viral immune escape. Apart from already existing mutations, we have identified three new immune escape sites: 1) Q493R, 2) G446S and 3) S371L/S373P/S375F that confers greater resistance to five of the six classes of RBD-antibodies. Structure of the Omicron S bound with human ACE2, together with analysis of sequence conservation in ACE2 binding region of 25 sarbecovirus members as well as heatmaps of the immunogenic sites and their corresponding mutational frequencies sheds light on conserved and structurally restrained regions that can be used for the development of broad-spectrum vaccines and therapeutics.

A subset of Memory B-derived antibody repertoire from 3-dose vaccinees is ultrapotent against diverse and highly transmissible SARS-CoV-2 variants, including Omicron (preprint)

Omicron, the most heavily mutated SARS-CoV-2 variant so far, is highly resistant to neutralizing antibodies, raising unprecedented concerns about the effectiveness of antibody therapies and vaccines. We examined whether sera from individuals who received two or three doses of inactivated vaccine, could neutralize authentic Omicron. The seroconversion rates of neutralizing antibodies were 3.3% (2/60) and 95% (57/60) for 2- and 3-dose vaccinees, respectively. For three-dose recipients, the geometric mean neutralization antibody titer (GMT) of Omicron was 15, 16.5-fold lower than that of the ancestral virus (254). We isolated 323 human monoclonal antibodies derived from memory B cells in 3-dose vaccinees, half of which recognize the receptor binding domain (RBD) and show that a subset of them (24/163) neutralize all SARS-CoV-2 variants of concern (VOCs), including Omicron, potently. Therapeutic treatments with representative broadly neutralizing mAbs individually or antibody cocktails were highly protective against SARS-CoV-2 Beta infection in mice. Atomic structures of the Omicron S in complex with three types of all five VOC-reactive antibodies defined the binding and neutralizing determinants and revealed a key antibody escape site, G446S, that confers greater resistance to one major class of antibodies bound at the right shoulder of RBD through altering local conformation at the binding interface. Our results rationalize the use of 3-dose immunization regimens and suggest that the fundamental epitopes revealed by these broadly ultrapotent antibodies are a rational target for a universal sarbecovirus vaccine. One sentence summary A sub-set of antibodies derived from memory B cells of volunteers vaccinated with 3 doses of an inactivated SARS-CoV-2 vaccine work individually as well as synergistically to keep variants, including Omicron, at bay.

Comprehensive genomic, immunological and clinical analysis of COVID-19 vaccine breakthrough infections: a prospective, comparative cohort study (preprint)

Objectives: As the COVID-19 pandemic is still ongoing and SARS-CoV-2 variants are circulating worldwide, an increasing number of breakthrough infections have been detected despite the good efficacy of COVID-19 vaccines. Methods: A prospective, comparative cohort study was conducted in Beijing Ditan Hospital to evaluate the clinical, immunological and genomic characteristics of COVID-19 breakthrough infections. Data on 88 COVID-19 breakthrough cases (vaccinated group) and 41 unvaccinated cases (unvaccinated group) from June 1 to August 20, 2021 were extracted from a cloud database. Among these 129 COVID-19 cases, we successfully sequenced 33 whole genomes, including 16 from the vaccinated group and 17 from the unvaccinated group. Results: Asymptomatic and mild cases predominated in both groups, but 2 patients developed severe disease in the unvaccinated group. Between the two groups, the median time of viral shedding in the vaccinated group were significantly lower than those in the unvaccinated group (p = 0.003). A comparison of dynamic IgG titres of cases in the two groups indicated that IgG titres in the vaccinated group showed a significantly increasing trend (P =0.028). The CD4+T lymphocyte count was lower in the unvaccinated group, and there was a significant difference between the two groups (p=0.018). In the vaccinated group, the number of moderate cases who received Sinopharm BBIBP (42 cases) was significantly higher than those who received Sinovac Coronavac (p=0.020). Whole-genome sequencing revealed 23 cases of delta variants, including 15 patients from the vaccinated group. However, no significant difference was observed in either the RT-qPCR results or viral shedding time. Conclusions: COVID-19 vaccine breakthrough infections were mainly asymptomatic and mild, the IgG titres were significantly higher and increased rapidly, and the viral shedding was short. Delta variants may be more likely to cause breakthrough infections, and vaccination may not reduce the viral loads and shedding time.

DNA damage contributes to age-associated differences in SARS-CoV-2 infection (preprint)

Coronavirus disease 2019 (COVID-19), caused by coronavirus SARS-CoV-2, is known to disproportionately affect older individuals1,2. How aging processes affect the disease progression remains largely unknown. Here we found that DNA damage, one of the major causes of aging3, promoted susceptibility to SARS-CoV-2 infection in cells and intestinal organoids. SARS-CoV-2 entry was facilitated by DNA damage caused by telomere attrition or extrinsic genotoxic stress and hampered by inhibition of DNA damage response (DDR). Mechanistic analysis revealed that DDR increased expression of ACE2, the receptor of SARS-CoV-2, by activation of transcription factor c-Jun in vitro and in vivo. Expression of ACE2 was elevated in the older tissues and positively correlated with γH2Ax and phosphorylated c-Jun (p-c-Jun). Finally, targeting DNA damage by increasing the DNA repair capacity, alleviated cell susceptibility to SARS-CoV-2. Our data provide insights into the age-associated differences in SARS-CoV-2 infection and a novel target for anti-viral intervention.

Basic epidemiological parameter values from data of real-world in mega-cities: the characteristics of COVID-19 in Beijing, China (preprint)

Background: With the spread of SARS-CoV-2 worldwide, understanding the basic epidemiological parameter values of COVID-19 from real-world data in mega-cities is essential for disease prevention and control. Methods: . To investigate the epidemiological parameters in SARS-CoV-2 infected cases in Beijing, we studied all confirmed cases and close contacts in Beijing from Jan 1st to Apr 3rd 2020. The epidemiological and virological characteristics of SARS-CoV-2 were analyzed. Results: . A total of 602 cases were positive for SARS-CoV-2, including 585 confirmed patients and 17 asymptomatic infections. The imported cases were mainly from Wuhan initially and then from abroad. Among 585 confirmed case-patients, the median age was 39 years old. The mean incubation period was 6.3 days. The secondary attack rate among households was higher than social contacts (15.6 vs 4.6%). The secondary attack rate of healthcare workers (HCWs) was higher than non-HCWs’ (7.3 vs 4.2%). The basic reproduction number was 2.0, and the average serial interval was 7.6 days. No significant genetic variant was identified. Conclusions: . The transmissibility of SARS-CoV-2 was relatively high, especially among households and from HCWs, which draws specific public health attention. So far, no evidence of widespread circulation of SARS-CoV-2 in communities in Beijing was found.