An mRNA-based T-cell-inducing antigen strengthens COVID-19 vaccine against SARS-CoV-2 variants.

Herd immunity achieved through mass vaccination is an effective approach to prevent contagious diseases. Nonetheless, emerging SARS-CoV-2 variants with frequent mutations largely evaded humoral immunity induced by Spike-based COVID-19 vaccines. Herein, we develop a lipid nanoparticle (LNP)-formulated mRNA-based T-cell-inducing antigen, which targeted three SARS-CoV-2 proteome regions that enriched human HLA-I epitopes (HLA-EPs). Immunization of HLA-EPs induces potent cellular responses to prevent SARS-CoV-2 infection in humanized HLA-A*02:01/DR1 and HLA-A*11:01/DR1 transgenic mice. Of note, the sequences of HLA-EPs are highly conserved among SARS-CoV-2 variants of concern. In humanized HLA-transgenic mice and female rhesus macaques, dual immunization with the LNP-formulated mRNAs encoding HLA-EPs and the receptor-binding domain of the SARS-CoV-2 B.1.351 variant (RBDbeta) is more efficacious in preventing infection of SARS-CoV-2 Beta and Omicron BA.1 variants than single immunization of LNP-RBDbeta. This study demonstrates the necessity to strengthen the vaccine effectiveness by comprehensively stimulating both humoral and cellular responses, thereby offering insight for optimizing the design of COVID-19 vaccines.

Inactivated vaccine-elicited potent antibodies can broadly neutralize SARS-CoV-2 circulating variants.

A full understanding of the inactivated COVID-19 vaccine-mediated antibody responses to SARS-CoV-2 circulating variants will inform vaccine effectiveness and vaccination development strategies. Here, we offer insights into the inactivated vaccine-induced antibody responses after prime-boost vaccination at both the polyclonal and monoclonal levels. We characterized the VDJ sequence of 118 monoclonal antibodies (mAbs) and found that 20 neutralizing mAbs showed varied potency and breadth against a range of variants including XBB.1.5, BQ.1.1, and BN.1. Bispecific antibodies (bsAbs) based on nonoverlapping mAbs exhibited enhanced neutralizing potency and breadth against the most antibody-evasive strains, such as XBB.1.5, BQ.1.1, and BN.1. The passive transfer of mAbs or their bsAb effectively protected female hACE2 transgenic mice from challenge with an infectious Delta or Omicron BA.2 variant. The neutralization mechanisms of these antibodies were determined by structural characterization. Overall, a broad spectrum of potent and distinct neutralizing antibodies can be induced in individuals immunized with the SARS-CoV-2 inactivated vaccine BBIBP-CorV, suggesting the application potential of inactivated vaccines and these antibodies for preventing infection by SARS-CoV-2 circulating variants.

Dynamics of T follicular helper cells in patients with rheumatic diseases and subsequent antibody responses in a three-dose immunization regimen of CoronaVac.

Given increased acceptance of the CoronaVac, there is an unmet need to assess the safety and immunogenic changes of CoronaVac in patients with rheumatic diseases (RD). Here we comprehensively analysed humoral and cellular responses in patient with RD after a three-dose immunization regimen of CoronaVac. RD patients with stable condition and/or low disease activity (n = 40) or healthy controls (n = 40) were assigned in a 1:1 ratio to receive CoronaVac (Sinovac). The prevalence of anti-receptor binding domain (RBD) antibodies and neutralizing antibodies was similar between healthy control (HC) and RD patients after the second and the third vaccination. However, the titers of anti-RBD IgG and neutralizing antibodies were significantly lower in RD patients compared to HCs (p < 0.05), which was associated with an impaired T follicular helper (Tfh) cell response. Among RD patients, those who generated an antibody response displayed a significantly higher Tfh cells compared to those who failed after the first and the second vaccination (p < 0.05). Interestingly, subjects with a negative serological response displayed a similar Tfh memory response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-derived peptides as their anti-RBD IgG positive counterpart, and all (4/4) of the non-responders in HCs, and 62.5% (5/8) of the non-responders in patients with RD displayed a positive serological response following the third dose. No serious adverse events were observed. In conclusion, our findings support SARS-CoV-2 vaccination in patients with RD with stable and/or low disease activity. The impaired ability in generating vaccine-specific antibodies in patients with RD was associated with a reduction in Tfh cells induction. The window of vaccination times still needs to be explored in future studies. Clinical trial registration: This trial was registered with ChiCTR2100049138.

A Retinol Derivative Inhibits SARS-CoV-2 Infection by Interrupting Spike-Mediated Cellular Entry.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological agent of the global pandemic and life-threatening coronavirus disease 2019 (COVID-19). Although vaccines and therapeutic antibodies are available, their efficacy is continuously undermined by rapidly emerging SARS-CoV-2 variants. Here, we found that all-trans retinoic acid (ATRA), a vitamin A (retinol) derivative, showed potent antiviral activity against all SARS-CoV-2 variants in both human cell lines and human organoids of the lower respiratory tract. Mechanistically, ATRA directly binds in a deep hydrophobic pocket of the receptor binding domain (RBD) located on the top of the SARS-CoV-2 spike protein (S) trimer. The bound ATRA mediates strong interactions between the "down" RBDs and locks most of the S trimers in an RBD "all-down" and ACE2-inaccessible inhibitory conformation. In summary, our results reveal the pharmacological biotargets and structural mechanism of ATRA and other retinoids in SARS-CoV-2 infection and suggest that ATRA and its derivatives could be potential hit compounds against a broad spectrum of coronaviruses. IMPORTANCE Retinoids, a group of compounds including vitamin A and its active metabolite all-trans retinoic acid (ATRA), regulate serial physiological activity in multiple organ systems, such as cell growth, differentiation, and apoptosis. The ATRA analogues reported to date include more than 4,000 natural and synthetic molecules that are structurally and/or functionally related to ATRA. Here, we found that ATRA showed potent antiviral activity against all SARS-CoV-2 variants by directly binding in a deep hydrophobic pocket of the receptor binding domain (RBD) located on top of the SARS-CoV-2 spike protein (S) trimer. The bound ATRA mediates strong interactions between the "down" RBDs and locks most of the S trimers in an RBD "all-down" and ACE2-inaccessible inhibitory conformation, suggesting the pharmacological feasibility of using ATRA or its derivatives as a remedy for and prevention of COVID-19 disease.

The Cross-Protective Immunity Landscape Among Different SARS-CoV-2 Variant RBDs.

Despite the fact that SARS-CoV-2 vaccines have been available in most parts of the world, the epidemic status remains grim with new variants emerging and escaping the immune protection of existing vaccines. Therefore, the development of more effective antigens and evaluation of their cross-protective immunity against different SARS-CoV-2 variants are particularly urgent. In this study, we expressed the wild type (WT), Alpha, Beta, Delta, and Lambda RBD proteins to immunize mice and evaluated their cross-neutralizing activity against different pseudoviruses (WT, Alpha, Beta, Delta, Lambda, and Omicron). All monovalent and pentavalent RBD antigens induced high titers of IgG antibodies against different variant RBD antigens. In contrast, WT RBD antigen-induced antibodies showed a lower neutralizing activity against Beta, Delta, Lambda, and Omicron pseudoviruses compared to neutralization against itself. Interestingly, Beta RBD antigen and multivalent antigen induced broader cross-neutralization antibodies than other variant RBD antigens. These data provide a reference for vaccine strain selection and universal COVID-19 vaccine design to fight the constant emergence of new SARS-CoV-2 variants.

A glucose-like metabolite deficient in diabetes inhibits cellular entry of SARS-CoV-2.

The severity and mortality of COVID-19 are associated with pre-existing medical comorbidities such as diabetes mellitus. However, the underlying causes for increased susceptibility to viral infection in patients with diabetes is not fully understood. Here we identify several small-molecule metabolites from human blood with effective antiviral activity against SARS-CoV-2, one of which, 1,5-anhydro-D-glucitol (1,5-AG), is associated with diabetes mellitus. The serum 1,5-AG level is significantly lower in patients with diabetes. In vitro, the level of SARS-CoV-2 replication is higher in the presence of serum from patients with diabetes than from healthy individuals and this is counteracted by supplementation of 1,5-AG to the serum from patients. Diabetic (db/db) mice undergo SARS-CoV-2 infection accompanied by much higher viral loads and more severe respiratory tissue damage when compared to wild-type mice. Sustained supplementation of 1,5-AG in diabetic mice reduces SARS-CoV-2 loads and disease severity to similar levels in nondiabetic mice. Mechanistically, 1,5-AG directly binds the S2 subunit of the SARS-CoV-2 spike protein, thereby interrupting spike-mediated virus-host membrane fusion. Our results reveal a mechanism that contributes to COVID-19 pathogenesis in the diabetic population and suggest that 1,5-AG supplementation may be beneficial to diabetic patients against severe COVID-19.

GP73 is a glucogenic hormone contributing to SARS-CoV-2-induced hyperglycemia.

Severe cases of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are associated with elevated blood glucose levels and metabolic complications. However, the molecular mechanisms for how SARS-CoV-2 infection alters glycometabolic control are incompletely understood. Here, we connect the circulating protein GP73 with enhanced hepatic gluconeogenesis during SARS-CoV-2 infection. We first demonstrate that GP73 secretion is induced in multiple tissues upon fasting and that GP73 stimulates hepatic gluconeogenesis through the cAMP/PKA signaling pathway. We further show that GP73 secretion is increased in cultured cells infected with SARS-CoV-2, after overexpression of SARS-CoV-2 nucleocapsid and spike proteins and in lungs and livers of mice infected with a mouse-adapted SARS-CoV-2 strain. GP73 blockade with an antibody inhibits excessive glucogenesis stimulated by SARS-CoV-2 in vitro and lowers elevated fasting blood glucose levels in infected mice. In patients with COVID-19, plasma GP73 levels are elevated and positively correlate with blood glucose levels. Our data suggest that GP73 is a glucogenic hormone that likely contributes to SARS-CoV-2-induced abnormalities in systemic glucose metabolism.

The self-assembled nanoparticle-based trimeric RBD mRNA vaccine elicits robust and durable protective immunity against SARS-CoV-2 in mice.

As COVID-19 continues to spread rapidly worldwide and variants continue to emerge, the development and deployment of safe and effective vaccines are urgently needed. Here, we developed an mRNA vaccine based on the trimeric receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) protein fused to ferritin-formed nanoparticles (TF-RBD). Compared to the trimeric form of the RBD mRNA vaccine (T-RBD), TF-RBD delivered intramuscularly elicited robust and durable humoral immunity as well as a Th1-biased cellular response. After further challenge with live SARS-CoV-2, immunization with a two-shot low-dose regimen of TF-RBD provided adequate protection in hACE2-transduced mice. In addition, the mRNA template of TF-RBD was easily and quickly engineered into a variant vaccine to address SARS-CoV-2 mutations. The TF-RBD multivalent vaccine produced broad-spectrum neutralizing antibodies against Alpha (B.1.1.7) and Beta (B.1.351) variants. This mRNA vaccine based on the encoded self-assembled nanoparticle-based trimer RBD provides a reference for the design of mRNA vaccines targeting SARS-CoV-2.

Fiscal response to the COVID-19 crisis in advanced and emerging market economies†

Abstract The fiscal policy response to the COVID-19 crisis was swift and strong, in tandem with monetary policy. Advanced economies (AEs) deployed a much larger fiscal response than emerging market economies (EMEs) throughout the pandemic. This study focuses on the drivers of this divergent fiscal response in the first months of the pandemic. Apart from the fact that EMEs entered the crisis later than AEs, narrower fiscal policy space in EMEs, further reduced by the tightening of their financing conditions in the early stages of the pandemic, constrained their fiscal response. The size and composition of the fiscal response also depended on some structural factors, such as the level of income, the strength of the social safety nets and automatic stabilisers.

A recombinant receptor-binding domain in trimeric form generates protective immunity against SARS-CoV-2 infection in nonhuman primates.

A safe and effective vaccine is critical to combat the COVID-19 pandemic. Here, we developed a trimeric SARS-CoV-2 receptor-binding domain (RBD) subunit vaccine candidate that simulates the natural structure of the spike (S) trimer glycoprotein. Immunization with the RBD trimer-induced robust humoral and cellular immune responses, and a high level of neutralizing antibodies was maintained for at least 4.5 months. Moreover, the antibodies that were produced in response to the vaccine effectively cross-neutralized the SARS-CoV-2 501Y.V2 variant (B.1.351). Of note, when the vaccine-induced antibodies dropped to a sufficiently low level, only one boost quickly activated the anamnestic immune response, conferring full protection against a SARS-CoV-2 challenge in rhesus macaques without typical histopathological changes in the lung tissues. These results demonstrated that the SARS-CoV-2 RBD trimer vaccine candidate is highly immunogenic and safe, providing long-lasting, broad, and significant immunity protection in nonhuman primates, thereby offering an optimal vaccination strategy against COVID-19.

Changes in the Pathogenic Spectrum of Acute Respiratory Tract Infections During the COVID-19 Epidemic in Beijing, China (preprint)

Background: Public health measures against COVID-19 may influence other disease epidemics. Many countries have reported significant reductions in influenza activity in 2020–2021, but the prevalence of other respiratory pathogens during the COVID-19 pandemic has rarely been reported, especially in China.Methods: Data from the Respiratory Pathogen Surveillance System in Beijing were analyzed to compare pathogen infection rates before the COVID-19 (from 1 February 2015 to 31 January 2020) and during the COVID-19 (from 1 February 2020 to 31 January 2021).Findings: Among 41630 acute respiratory tract infections 13630 had at least one pathogen positive result, which decreased from 32·16% (95% CI 31·69%, 32·64%) before the COVID-19 to 10·97% (95% CI 10·03%, 11·96%) during the COVID-19, representing a 65·90% decrease (P<0·001). The positivity rate fluctuated with the strictness of public health measures. Before the COVID-19 epidemic, the top five of the pathogenic spectrums were IFV (26·27%), MP (19·30%), HPIV (11·80%), HRV (9·38%), and EV (8·38%), while during the COVID-19, the top five were seasonal HCoV (21·10%), HRV (18·99%), HPIV (14·98%), IFV (13·08%), and RSV (10.76%).Interpretation: The prevalence of respiratory pathogens decreased significantly during the COVID-19, closely relating to public health measures against COVID-19; these measures can serve as useful strategies for the prevention and control of other respiratory tract infections.Funding Statement: The National Major Science and Technology Project for Control and Prevention of Major Infectious Diseases in China (2017ZX10103004).Declaration of Interests: FH received funds from the National Major Science and Technology Project for Control and Prevention of Major Infectious Diseases in China (2017ZX10103004). All other authors declare no competing interests.Ethics Approval Statement: Ethics approval for the protocol of this study was obtained from the Ethics Committee of the BJCDC. Written informed consent was obtained.

A predictive model for respiratory distress in patients with COVID-19: a retrospective study.

BACKGROUND: Coronavirus disease 2019 (COVID-19), associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global public health crisis. We retrospectively evaluated 863 hospitalized patients with COVID-19 infection, designated IWCH-COVID-19. METHODS: We built a successful predictive model after investigating the risk factors to predict respiratory distress within 30 days of admission. These variables were analyzed using Kaplan-Meier and Cox proportional hazards (PHs) analyses. Hazard ratios (HRs) and performance of the final model were determined. RESULTS: Neutrophil count >6.3×109/L, D-dimer level ≥1.00 mg/L, and temperature ≥37.3 °C at admission showed significant positive association with the outcome of respiratory distress in the final model. Complement C3 (C3) of 0.9-1.8 g/L, platelet count >350×109/L, and platelet count of 125-350×109/L showed a significant negative association with outcomes of respiratory distress in the final model. The final model had a C statistic of 0.891 (0.867-0.915), an Akaike's information criterion (AIC) of 567.65, and a bootstrap confidence interval (CI) of 0.866 (0.842-0.89). This five-factor model could help in early allocation of medical resources. CONCLUSIONS: The predictive model based on the five factors obtained at admission can be applied for calculating the risk of respiratory distress and classifying patients at an early stage. Accordingly, high-risk patients can receive timely and effective treatment, and health resources can be allocated effectively.

[Clinical characteristics and outcomes of adult critically ill patients with COVID-19 in Honghu, Hubei Province].

OBJECTIVE: To explore the clinical characteristics and outcomes of adult critically ill patients with COVID-19 and identify the risk factors correlated with in-hospital deaths. METHODS: This study was conducted among 20 confirmed adult cases of COVID-19 in the Intensive Care Unit (ICU) of Honghu People's Hospital in Jingzhou City, Hubei Province. According to the final outcome, the patients were divided into survivor group and death group with 10 patients each. The demographic data, clinical manifestations and signs, laboratory findings, treatment measures and clinical outcomes were obtained from electronic medical records to compare the clinical characteristics and outcomes between the two groups. Univariate logistic analysis was used to analyze the risk factors associated with in-hospital death. RESULTS: The mean age of patients with confirmed COVID-19 was 70 ± 12 years, and 40% of them were male. The patients were admitted to ICU 11 ± 9 days after symptom onset. The most common symptoms on admission were cough (19 cases), fatigue or myalgia (18 cases), fever (17 cases) and dyspnea (16 cases). Eleven (55%) of the patients had underlying diseases, among which hypertension was the most common (11 cases), followed by cardiovascular disease (4 cases) and diabetes (3 cases). Six (30%) of the patients received invasive mechanical ventilation and continued renal replacement therapy but eventually died. Acute cardiac injury was the most common complication (19 cases). Half of the patients died between the 2nd and 19th day after ICU admission. Compared with dead patients, the surviving patients had a lower average body weight (61.70±2.36 vs 68.60±7.15 kg, P=0.01) and a higher Glasgow Coma Index (14.69 ± 0.70 vs 12.70 ± 2.45, P=0.03), and were less likely to develop shock (2 vs 10, P=0.001) or acute respiratory distress syndrome (2 vs 10, P=0.001). CONCLUSIONS: Critically ill patients with COVID-19 are generally older. A higher body weight and a lower lymphocyte count are potentially associated with a greater likeliness of fatality in ICU patients with COVID-19.

[Diagnosis and treatment of an elderly patient with secondary cerebral infarction caused by COVID-19].

We review the experience with the diagnosis and treatment of secondary cerebral infarction in an elderly patient with coronavirus disease 2019 (COVID-19). COVID-19 has rapid disease progression with a high mortality rate in elderly patients, and physicians should be alert to secondary bacterial infection that may result in coagulation dysfunction and cerebral infarction. Early anti-infection therapy, immune regulation and appropriate anticoagulation intervention may help improve the prognosis of the patients.