Rational development of multicomponent mRNA vaccine candidates against mpox.

The re-emerging mpox (formerly monkeypox) virus (MPXV), a member of Orthopoxvirus genus together with variola virus (VARV) and vaccinia virus (VACV), has led to public health emergency of international concern since July 2022. Inspired by the unprecedent success of coronavirus disease 2019 (COVID-19) mRNA vaccines, the development of a safe and effective mRNA vaccine against MPXV is of high priority. Based on our established lipid nanoparticle (LNP)-encapsulated mRNA vaccine platform, we rationally constructed and prepared a panel of multicomponent MPXV vaccine candidates encoding different combinations of viral antigens including M1R, E8L, A29L, A35R, and B6R. In vitro and in vivo characterization demonstrated that two immunizations of all mRNA vaccine candidates elicit a robust antibody response as well as antigen-specific Th1-biased cellular response in mice. Importantly, the penta- and tetra-component vaccine candidates AR-MPXV5 and AR-MPXV4a showed superior capability of inducing neutralizing antibodies as well as of protecting from VACV challenge in mice. Our study provides critical insights to understand the protection mechanism of MPXV infection and direct evidence supporting further clinical development of these multicomponent mRNA vaccine candidates.

Transmission risk of asymptomatic SARS-CoV-2 infection: A systematic review and meta-analysis

Background Global evidence on the transmission of asymptomatic SARS-CoV-2 infection needs to be synthesized. Methods A search of 4 electronic databases (PubMed, EMBASE, Cochrane Library, and Web of Science databases) as of January 24, 2021 was performed. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Studies which reported the transmission rate among close contacts with asymptomatic SARS-CoV-2 cases were included, and transmission activities occurred were considered. The transmission rates were pooled by zero-inflated beta distribution. The risk ratios (RRs) were calculated using random-effects models. Results Of 4923 records retrieved and reviewed, 15 studies including 3917 close contacts with asymptomatic indexes were eligible. The pooled transmission rates were 1.79 per 100 person-days (or 1.79%, 95% confidence interval [CI] 0.41%–3.16%) by asymptomatic index, which is significantly lower than by presymptomatic (5.02%, 95% CI 2.37%–7.66%;P<.001), and by symptomatic (5.27%, 95% CI 2.40%–8.15%;P<.001). Subgroup analyses showed that the household transmission rate of asymptomatic index was (4.22%, 95% CI 0.91%–7.52%), four times significantly higher than non-household transmission (1.03%, 95% CI 0.73%–1.33%;P=.03), and the asymptomatic transmission rate in China (1.82%, 95% CI 0.11%–3.53%) was lower than in other countries (2.22%, 95% CI 0.67%–3.77%;P=.01). Conclusions People with asymptomatic SARS-CoV-2 infection are at risk of transmitting the virus to their close contacts, particularly in household settings. The transmission potential of asymptomatic infection is lower than symptomatic and presymptomatic infections. This meta-analysis provides evidence for predicting the epidemic trend and promulgating vaccination and other control measures. Trial Registration Registered with PROSPERO International Prospective Register of Systematic Reviews, CRD42021269446;https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=269446

Risk of SARS-CoV-2 reinfection: a systematic review and meta-analysis.

This meta-analysis aims to synthesize global evidence on the risk of reinfection among people previously infected with SARS-CoV-2. We systematically searched PubMed, Scopus, Embase and Web of Science as of April 5, 2021. We conducted: (1) meta-analysis of cohort studies containing data sufficient for calculating the incidence rate of SARS-CoV-2 reinfection; (2) systematic review of case reports with confirmed SARS-CoV-2 reinfection cases. The reinfection incidence was pooled by zero-inflated beta distribution. The hazard ratio (HR) between reinfection incidence among previously infected individuals and new infection incidence among infection-naïve individuals was calculated using random-effects models. Of 906 records retrieved and reviewed, 11 studies and 11 case reports were included in the meta-analysis and the systematic review, respectively. The pooled SARS-CoV-2 reinfection incidence rate was 0.70 (standard deviation [SD] 0.33) per 10,000 person-days. The incidence of reinfection was lower than the incidence of new infection (HR = 0.12, 95% confidence interval 0.09-0.17). Our meta-analysis of studies conducted prior to the emergency of the more transmissible Omicron variant showed that people with a prior SARS-CoV-2 infection could be re-infected, and they have a lower risk of infection than those without prior infection. Continuing reviews are needed as the reinfection risk may change due to the rapid evolution of SARS-CoV-2 variants.

Rational development of a combined mRNA vaccine against COVID-19 and influenza.

As the world continues to experience the COVID-19 pandemic, seasonal influenza remain a cause of severe morbidity and mortality globally. Worse yet, coinfection with SARS-CoV-2 and influenza A virus (IAV) leads to more severe clinical outcomes. The development of a combined vaccine against both COVID-19 and influenza is thus of high priority. Based on our established lipid nanoparticle (LNP)-encapsulated mRNA vaccine platform, we developed and characterized a novel mRNA vaccine encoding the HA antigen of influenza A (H1N1) virus, termed ARIAV. Then, ARIAV was combined with our COVID-19 mRNA vaccine ARCoV, which encodes the receptor-binding domain (RBD) of the SARS-CoV-2 S protein, to formulate the final combined vaccine, AR-CoV/IAV. Further characterization demonstrated that immunization with two doses of AR-CoV/IAV elicited robust protective antibodies as well as antigen-specific cellular immune responses against SARS-CoV-2 and IAV. More importantly, AR-CoV/IAV immunization protected mice from coinfection with IAV and the SARS-CoV-2 Alpha and Delta variants. Our results highlight the potential of the LNP-mRNA vaccine platform in preventing COVID-19 and influenza, as well as other respiratory diseases.

Longitudinal Dynamics of Cellular Responses in Recovered COVID-19 Patients.

Safe and effective vaccines and therapeutics based on the understanding of antiviral immunity are urgently needed to end the COVID-19 pandemic. However, the understanding of these immune responses, especially cellular immune responses to SARS-CoV-2 infection, is limited. Here, we conducted a cohort study of COVID-19 patients who were followed and had blood collected to characterize the longitudinal dynamics of their cellular immune responses. Compared with healthy controls, the percentage of activation of SARS-CoV-2 S/N-specific T cells in recovered patients was significantly higher. And the activation percentage of S/N-specific CD8+ T cells in recovered patients was significantly higher than that of CD4+ T cells. Notably, SARS-CoV-2 specific T-cell responses were strongly biased toward the expression of Th1 cytokines, included the cytokines IFNγ, TNFα and IL2. Moreover, the secreted IFNγ and IL2 level in severe patients was higher than that in mild patients. Additionally, the number of IFNγ-secreting S-specific T cells in recovered patients were higher than that of N-specific T cells. Overall, the SARS-CoV-2 S/N-specific T-cell responses in recovered patients were strong, and virus-specific immunity was present until 14-16 weeks after symptom onset. Our work provides a basis for understanding the immune responses and pathogenesis of COVID-19. It also has implications for vaccine development and optimization and speeding up the licensing of the next generation of COVID-19 vaccines.

The Effects of BITs on Contract Execution in Developing Countries: Some Implications for the COVID-19 Crisis.

Bilateral investment agreements are bilateral treaties between capital exporting countries and host countries, which is specially used to protect international investment, and the contract execution is directly related to the daily operation of multinational enterprises. Based on the panel data of 73 developing countries from 2005 to 2019, this paper examines the improvement effect of BITs on the contract execution of host countries. The study found that both the overall bilateral investment agreements and the bilateral investment agreements in force can significantly improve the contract execution of the host country. Due to the differences between the civil law system and the common law system in many aspects, such as the source of evidence and trial mode, the effect of BITs on the improvement of contract execution in host countries of the common law system is more prominent. In terms of specific impact, the improvement effect of BITs on time is significantly better than cost. The core conclusion is still valid after changing the estimation method and eliminating abnormal samples.

Rational development of a combined mRNA vaccine against COVID-19 and influenza (preprint)

As the world continues to experience the COVID-19 pandemic, seasonal influenza remain a cause of severe morbidity and mortality globally. Worse yet, coinfection with SARS-CoV-2 and influenza A virus (IAV) leads to more severe clinical outcomes. The development of a combined vaccine against both COVID-19 and influenza is thus of high priority. Based on our established lipid nanoparticle (LNP)-encapsulated mRNA vaccine platform, we developed and characterized a novel mRNA vaccine encoding the HA antigen of influenza A (H1N1) virus, termed ARIAV. Then, ARIAV was combined with our COVID-19 mRNA vaccine ARCoV, which encodes the receptor binding domain (RBD) of the SARS-CoV-2 S protein, to formulate the final combined vaccine, AR-CoV/IAV. Further characterization demonstrated that immunization with two doses of AR-CoV/IAV elicited robust protective antibodies as well as antigen-specific cellular immune responses against SARS-CoV-2 and IAV. More importantly, AR-CoV/IAV immunization protected mice from coinfection with IAV and the SARS-CoV-2 Alpha and Delta variants. Our results highlight the potential of the LNP-mRNA vaccine platform in preventing COVID-19 and influenza, as well as other respiratory diseases.

Comparative characterization of SARS-CoV-2 variants of concern and mouse-adapted strains in mice.

SARS-CoV-2 has evolved into a panel of variants of concern (VOCs) and constituted a sustained threat to global health. The wildtype (WT) SARS-CoV-2 isolates fail to infect mice, while the Beta variant, one of the VOCs, has acquired the capability to infect standard laboratory mice, raising a spreading risk of SARS-CoV-2 from humans to mice. However, the infectivity and pathogenicity of other VOCs in mice remain not fully understood. In this study, we systematically investigated the infectivity and pathogenicity of three VOCs, Alpha, Beta, and Delta, in mice in comparison with two well-understood SARS-CoV-2 mouse-adapted strains, MASCp6 and MASCp36, sharing key mutations in the receptor-binding domain (RBD) with Alpha or Beta, respectively. Our results showed that the Beta variant had the strongest infectivity and pathogenicity among the three VOCs, while the Delta variant only caused limited replication and mild pathogenic changes in the mouse lung, which is much weaker than what the Alpha variant did. Meanwhile, Alpha showed comparable infectivity in lungs in comparison with MASCp6, and Beta only showed slightly lower infectivity in lungs when compared with MASCp36. These results indicated that all three VOCs have acquired the capability to infect mice, highlighting the ongoing spillover risk of SARS-CoV-2 from humans to mice during the continued evolution of SARS-CoV-2, and that the key amino acid mutations in the RBD of mouse-adapted strains may be referenced as an early-warning indicator for predicting the spillover risk of newly emerging SARS-CoV-2 variants.

A highly immunogenic live-attenuated vaccine candidate prevents SARS-CoV-2 infection and transmission in hamsters.

The highly pathogenic and readily transmissible SARS-CoV-2 has caused a global coronavirus pandemic, urgently requiring effective countermeasures against its rapid expansion. All available vaccine platforms are being used to generate safe and effective COVID-19 vaccines. Here, we generated a live-attenuated candidate vaccine strain by serial passaging of a SARS-CoV-2 clinical isolate in Vero cells. Deep sequencing revealed the dynamic adaptation of SARS-CoV-2 in Vero cells, resulting in a stable clone with a deletion of seven amino acids (N679SPRRAR685) at the S1/S2 junction of the S protein (named VAS5). VAS5 showed significant attenuation of replication in multiple human cell lines, human airway epithelium organoids, and hACE2 mice. Viral fitness competition assays demonstrated that VAS5 showed specific tropism to Vero cells but decreased fitness in human cells compared with the parental virus. More importantly, a single intranasal injection of VAS5 elicited a high level of neutralizing antibodies and prevented SARS-CoV-2 infection in mice as well as close-contact transmission in golden Syrian hamsters. Structural and biochemical analysis revealed a stable and locked prefusion conformation of the S trimer of VAS5, which most resembles SARS-CoV-2-3Q-2P, an advanced vaccine immunogen (NVAX-CoV2373). Further systematic antigenic profiling and immunogenicity validation confirmed that the VAS5 S trimer presents an enhanced antigenic mimic of the wild-type S trimer. Our results not only provide a potent live-attenuated vaccine candidate against COVID-19 but also clarify the molecular and structural basis for the highly attenuated and super immunogenic phenotype of VAS5.

Lipid nanoparticle-encapsulated mRNA antibody provides long-term protection against SARS-CoV-2 in mice and hamsters.

Monoclonal antibodies represent important weapons in our arsenal to against the COVID-19 pandemic. However, this potential is severely limited by the time-consuming process of developing effective antibodies and the relative high cost of manufacturing. Herein, we present a rapid and cost-effective lipid nanoparticle (LNP) encapsulated-mRNA platform for in vivo delivery of SARS-CoV-2 neutralization antibodies. Two mRNAs encoding the light and heavy chains of a potent SARS-CoV-2 neutralizing antibody HB27, which is currently being evaluated in clinical trials, were encapsulated into clinical grade LNP formulations (named as mRNA-HB27-LNP). In vivo characterization demonstrated that intravenous administration of mRNA-HB27-LNP in mice resulted in a longer circulating half-life compared with the original HB27 antibody in protein format. More importantly, a single prophylactic administration of mRNA-HB27-LNP provided protection against SARS-CoV-2 challenge in mice at 1, 7 and even 63 days post administration. In a close contact transmission model, prophylactic administration of mRNA-HB27-LNP prevented SARS-CoV-2 infection between hamsters in a dose-dependent manner. Overall, our results demonstrate a superior long-term protection against SARS-CoV-2 conferred by a single administration of this unique mRNA antibody, highlighting the potential of this universal platform for antibody-based disease prevention and therapy against COVID-19 as well as a variety of other infectious diseases.

The relationship between online learning and eye strain in college students during the COVID-19 outbreak

Objective To describe online learning and eye strain situation of college students during the COVID-19 outbreak, to provide a scientific basis for guiding students' eye health. Methods A self-filled electronic questionnaire survey through questionnaire star was administered to college students across China. Information about online learning and eye strain of 1 046 college students during the epidemic was collected in Hefei, Anhui Province from March 16 to 20, 2020. The univariate and multivariate Logistic regression analysis were performed to analyze the association between online learning and eye strain of college students. Results The rate of eye strain during online learning was 72.1%, totally of 68.4% in 421 male students and 74.6% in 625 female students. Boys with online learning time < 6 h/d, slow internet access, difficulty in understanding online class reported higher rate of eye strain than girls(X 2=17.36, 8.72, 7.02, P < 0.05). Freshmen reported the highest rate of slow internet access occasionally and active online class(X 2=15.26, 16.11, P < 0.05), junior students reported highest rate of online learning time < 6 h/d, and easy understandable online class(X 2=15.33, 32.59, P < 0.05), medical college students reported higher rate of slow internet access, inactive online class than non-medical college students(X 2=11.79, 11.03, P < 0.05). Multivariate Logistic regression analysis showed that odds ratio(OR) of eye strain in females was 1.40 (1.06-1.87), compared with males;the OR of eye strain were 1.43 (1.01-2.03) and 1.54 (1.10-2.15) in the groups with online learning time 6- < 8 h/d and 8 h/d, respectively, compared with the group with online learning time < 6 h/d, the OR of eye strain in the groups with slow internet access was 2.28 (1.25-4.14), compared with students without slow internet access, the OR of eye strain in the capable-to-understand and difficult-to-understand group were 2.54 (1.73-3.74) and 5.40 (2.70-10.80) respectively, compared with the easy-to-understand group. Conclusion Female students, online learing time 8 h/d, slow internet access, difficult to understand class content were positively related with college students eye strain. Attention should be paid to the eye health of college students to reduce the adverse effects of online learning on vision.during the COVID-19 epidemic.

Long-term stability and protection efficacy of the RBD-targeting COVID-19 mRNA vaccine in nonhuman primates.

Messenger RNA (mRNA) vaccine technology has shown its power in preventing the ongoing COVID-19 pandemic. Two mRNA vaccines targeting the full-length S protein of SARS-CoV-2 have been authorized for emergency use. Recently, we have developed a lipid nanoparticle-encapsulated mRNA (mRNA-LNP) encoding the receptor-binding domain (RBD) of SARS-CoV-2 (termed ARCoV), which confers complete protection in mouse model. Herein, we further characterized the protection efficacy of ARCoV in nonhuman primates and the long-term stability under normal refrigerator temperature. Intramuscular immunization of two doses of ARCoV elicited robust neutralizing antibodies as well as cellular response against SARS-CoV-2 in cynomolgus macaques. More importantly, ARCoV vaccination in macaques significantly protected animals from acute lung lesions caused by SARS-CoV-2, and viral replication in lungs and secretion in nasal swabs were completely cleared in all animals immunized with low or high doses of ARCoV. No evidence of antibody-dependent enhancement of infection was observed throughout the study. Finally, extensive stability assays showed that ARCoV can be stored at 2-8 °C for at least 6 months without decrease of immunogenicity. All these promising results strongly support the ongoing clinical trial.

Characterization and structural basis of a lethal mouse-adapted SARS-CoV-2.

There is an urgent need for animal models to study SARS-CoV-2 pathogenicity. Here, we generate and characterize a novel mouse-adapted SARS-CoV-2 strain, MASCp36, that causes severe respiratory symptoms, and mortality. Our model exhibits age- and gender-related mortality akin to severe COVID-19. Deep sequencing identified three amino acid substitutions, N501Y, Q493H, and K417N, at the receptor binding domain (RBD) of MASCp36, during in vivo passaging. All three RBD mutations significantly enhance binding affinity to its endogenous receptor, ACE2. Cryo-electron microscopy analysis of human ACE2 (hACE2), or mouse ACE2 (mACE2), in complex with the RBD of MASCp36, at 3.1 to 3.7 Å resolution, reveals the molecular basis for the receptor-binding switch. N501Y and Q493H enhance the binding affinity to hACE2, whereas triple mutations at N501Y/Q493H/K417N decrease affinity and reduce infectivity of MASCp36. Our study provides a platform for studying SARS-CoV-2 pathogenesis, and unveils the molecular mechanism for its rapid adaptation and evolution.

Social media exposure during COVID-19 lockdowns could lead to emotional overeating via anxiety: The moderating role of neuroticism.

China was a major hotspot during the beginning of the COVID-19 pandemic. Several studies have reported changes in residents' eating behaviors and appetite during city wide lockdowns and home confinements. However, few have investigated how neuroticism interacts with the impact of COVID-19 to influence eating behaviors during city lockdowns. Thus, the current study aims to establish a pathway model to understand social media exposure, negative affect, neuroticism, and their interaction with eating behaviors during the COVID-19 lockdowns. We present data from 1,128 participants (Mage = 24.34 ± 10.48 years) who completed an online survey between February 17 and 27, 2020. The extent of respondents' social media exposure, negative affect, eating behaviors, and desire for high-calorie food during city lockdowns, as well as the personality trait of neuroticism, were measured. Results show that city lockdowns and home confinements had a negative impact on residents' eating behaviors and appetite. Forty-eight percent of respondents showed moderate to constant emotional overeating, and respondents' desire for high-calorie food significantly increased. Correlation analysis showed that emotional overeating is positively associated with social media exposure, neuroticism, and anxiety. Then, a moderated mediation model was established, showing that heavy social media exposure could lead to emotional overeating through anxiety, and the association between social media exposure and anxiety varies depending on the extent of neuroticism. The current study provides novel insight into how the interaction of a personality trait and the stressful situation of COVID-19 influence people's negative emotions and eating behaviors.

Clinical analysis of 71 COVID-19 death cases in Wuhan

Objective To study the factors influencing the death of the novel coronavirus disease 2019 (COVID-19) patients in Wuhan city of China. Methods The clinical data of 71 COVID-19 death cases admitted and treated in the Third Hospital of Wuhan were retrospectively analyzed. and SPSS 22.0 software was used for statistical analysis to compare the laboratory results in different periods of the disease. Results Males (64.79%. 46/71) accounted for a large proportion of the 71 cases of COVID-19 deaths in Wuhan city of China. The median age was 70.0 years old. 81.69% (58/71) were over 60 years old. People with underlying diseases accounted for 76.06% (54/71). the most common underlying disease was hypertension (53.52%. 38/71). and the most common clinical symptom was fever (85.91%. 61/71). The majority of the patients were severe type (56.34%. 40/71) at the time when they were admitted to the hospital. According to the laboratory results. their lactate dehydrogenase (LDH) [469.50 (454.50~552.75) U/L], blood glucose [9.95 (6.83~13.95) mmol/L] at the end stage were higher than that at admission with LDH [144.00 (123.75~273.25) U/L] and blood glucose [6.60 (5.20~10.70) mmol/L] (Z= -3.298, -2.542, both P < 0.05). Blood gas analysis at the end stage showed that their pH value [7.31 (7.27~7.34)]. oxygen partial pressure (PaO2) [45.00 (35.00~56.00) mm Hg] were lower than that at admission with the pH value [7.38 (7.34~7.41)] and PaO2 [82.50 (77.50~88.50) mm Meanwhile. their partial pressure of carbon dioxide (PaCO2) [59.00 (48.75~60.75) mm Hg] was higher than that at admission [42.00 (37.25~48.75) mm Hg] (Z= -2.906. -3.296. -3.206. all P < 0.05). Conclusions Elder age and combined underlying diseases account for a higher proportion of deaths. Lung injury. hypoxemia. myocardial injury, and abnormal glucose metabolism caused by the disease are the major causes of death in COVID-19 patients in Wuhan city of China.

Tourism and Livable Towns Beyond the Coronavirus Disease 2019: A Case Study for Chongqing, China.

Based on the data of 812 small towns in Chongqing, China, this paper attempts to conduct an empirical analysis on whether tourist towns with excellent natural environment, policy advantage, and market preference are more ecologically livable than ordinary small towns. It is found that as a whole, tourist towns are indeed more ecologically livable than ordinary small towns. Also, from the perspective of grading, both the national and provincial tourist towns have the advantage of ecological livability, but the advantage of national ones is more prominent. Furthermore, the ecological livability of tourist towns is affected by location advantage and policy inclination. The implications of the results are discussed following the outcomes of the coronavirus disease 2019 outbreak. The suggestions beyond the coronavirus disease 2019 are also provided.