Design of SARS-CoV-2 protease inhibitors with improved affinity and reduced sensitivity to mutations (preprint)

Inhibitors of the SARS-CoV-2 main protease (Mpro) such as nirmatrelvir (NTV) and ensitrelvir (ETV) have proven effective in reducing the severity of COVID-19, but the presence of resistance-conferring mutations in sequenced viral genomes raises concerns about future drug resistance. Second-generation oral drugs that retain function on these mutants are thus urgently needed. We hypothesized that the covalent HCV protease inhibitor boceprevir (BPV) could serve as the basis for orally bioavailable drugs that inhibit SARS-CoV-2 Mpro more tightly than existing drugs. Performing structure-guided modifications of BPV, we developed a picomolar-affinity inhibitor, ML2006a4, with antiviral activity, oral pharmacokinetics, and therapeutic efficacy similar or superior to NTV. A crucial feature of ML2006a4 is a novel derivatization of the ketoamide reactive group that improves cell permeability and oral bioavailability. Finally, ML2006a4 is less sensitive to several mutations that cause resistance to NTV or ETV and occur in the natural SARS-CoV-2 population. Thus, anticipatory drug design can preemptively address potential resistance mechanisms.

COVID-19 excess deaths in Eastern European countries associated with weaker regulation implementation and lower vaccination coverage

Background: Since winter 2020, excess deaths due to COVID-19 have been higher in Eastern Europe than most of Western Europe, partly because regulatory enforcement was poor. Methods: This paper analysed data from 50 countries in the WHO European Region, in addition to data from USA and Canada. Excess mMortality and vaccination data were retrieved from “Our World In Data” and regulation implementation was assessed using standard methods. Multiple linear regression was used to assess the association between mortality and each covariate. Results: Excess mortality increased by 4.1 per 100 000 (P = 0.038) for every percentage decrease in vaccination rate and with 6/100 000 (p=0.011) for every decreased unit in the regulatory implementation score a country achieved in the Rule of Law Index. Conclusion: Degree of regulation enforcement, likely including public health measure enforcement, may be an important factor in controlling COVID-19’s deleterious health impacts.

The Characteristics of Light-Duty Passenger Vehicle Mileage and Impact Analysis in China from a Big Data Perspective

Vehicle mileage is one of the key parameters for accurately evaluating vehicle emissions and energy consumption. With the support of the national annual vehicle emission inspection networked platform in China, this study used big data methods to analyze the activity level characteristics of the light-duty passenger vehicle fleet with the highest ownership proportion. We found that the annual mileage of vehicles does not decay significantly with the increase in vehicle age, and the mileage of vehicles is relatively low in the first few years due to the run-in period, among other reasons. This study indicated that the average mileage of the private passenger car fleet is 10,300 km/yr and that of the taxi fleet was 80,000 km/yr in China in 2019, and the annual mileage dropped by 22% in 2020 due to the pandemic. Based on the vehicle mileage characteristics, the emission inventory of major pollutants from light-duty passenger vehicles in China for 2010–2020 was able to be updated, which will provide important data support for more accurate environmental and climate benefit assessments in the future. [ FROM AUTHOR]

Latent profile analysis of security among patients with COVID-19 infection in mobile cabin hospitals and its relationship with psychological capital

Aim COVID-19 patients' security is related to their mental health. However, the classification of this group's sense of security is still unclear. The aim of our research is to clarify the subtypes of security of patients infected with COVID-19, explore the factors affecting profile membership, and examine the relationship between security and psychological capital for the purpose of providing a reference for improving patients' sense of security and mental health. Methods A total of 650 COVID-19 patients in a mobile cabin hospital were selected for a cross-sectional survey from April to May 2022. They completed online self-report questionnaires that included a demographic questionnaire, security scale, and psychological capital scale. Data analysis included latent profile analysis, variance analysis, the Chi-square test, multiple comparisons, multivariate logistical regression, and hierarchical regression analysis. Results Three latent profiles were identified—low security (Class 1), moderate security (Class 2), and high security (Class 3)—accounting for 12.00, 49.51, and 38.49% of the total surveyed patients, respectively. In terms of the score of security and its two dimensions, Class 3 was higher than Class 2, and Class 2 was higher than Class 1 (all P < 0.001). Patients with difficulty falling asleep, sleep quality as usual, and lower tenacity were more likely to be grouped into Class 1 rather than Class 3;Patients from families with a per capita monthly household income <3,000 and lower self-efficacy and hope were more likely to be grouped into Classes 1 and 2 than into Class 3. Psychological capital was an important predictor of security, which could independently explain 18.70% of the variation in the patients' security. Conclusions Security has different classification features among patients with COVID-19 infection in mobile cabin hospitals. The security of over half of the patients surveyed is at the lower or middle level, and psychological capital is an important predictor of the patients' security. Medical staff should actively pay attention to patients with low security and help them to improve their security level and psychological capital.

Extracellular disintegration of viral proteins as an innovative strategy for developing broad-spectrum antivirals against coronavirus (preprint)

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has claimed millions of lives worldwide, not to mention innumerable losses in the global economy and disruptions in social relationships. Unfortunately, state-of-the-art treatments still lag behind the fast emergence of new variants of concern. The key to resolve this issue is to develop broad-spectrum antivirals with innovative antiviral mechanisms in which coronaviruses are deactivated regardless of their variant development. Herein, we report a new antiviral strategy involving extracellular disintegration of viral proteins that are indispensable for viral infection with hyperanion-grafted enediyne molecules. The sulfate groups ensure low cellular permeability and rather low cytotoxicity of the molecules, while the core enediyne generates reactive radical species and causes significant damage to the spike (S) protein of coronavirus. The enediyne compounds exhibit antiviral activity at micromolar to nanomolar concentrations, and the selectivity index of up to 20,000 against four kinds of human coronaviruses, including the SARS-CoV-2 omicron variant, suggesting the high potential of this new strategy in combating the COVID-19 pandemic.

Research on High-Quality Development Evaluation, Space–Time Characteristics and Driving Factors of China’s Construction Industry under Carbon Emission Constraints

Research on the regional difference characteristics and driving mechanisms of high-quality developmental evaluations of the construction industry under the constraint of carbon emissions has important practical significance for guiding the efficient development of the construction industry, alleviating the contradiction between economic and social development and resource conservation, low-carbon requirements in the process of rapid urbanization, and realizing regional coordinated development. Taking carbon emissions as unexpected output into the evaluation system of high-quality development of construction industry, this paper studies the spatial–temporal differentiation characteristics, dynamic trend evolution and its driving factors of high-quality development of China’s construction industry from 2006 to 2021 by using the SE-SBM model of unexpected output, GML index analysis and grey correlation model. The research results show that: (1) from 2006 to 2021, the high-quality development of the construction industry generally fluctuated in a sinusoidal function pattern, and the high-quality development level of the construction industry in China was improved as a whole. It is manifested in the coexistence of regional imbalance and spatial correlation. High-efficiency provinces are concentrated in the eastern coastal areas, forming an obvious cluster effect;however, the radiation-driving effect is weak. (2) The regional difference in technological scale change is the largest, which is the main reason for the difference in regional total factor production growth rate;the contribution of technological progress to the difference in total factor growth rate is also relatively large. Generally speaking, technological factors are the key to reducing the difference of total factor growth rate between regions. (3) Urbanization level, carbon emission constraints, government regulation, scientific and technological R & D investment and industrial structure upgrading are the main driving factors that affect the spatiotemporal differentiation and evolution of high-quality development of the construction industry.

Influence of the domestic COVID-19 pandemic on the pediatric emergency department

Objectives After the coronavirus disease 2019 (COVID-19) pandemic emerged, there has been a substantial decline in emergency department (ED) visits. However, the impact of the pandemic on pediatric ED (PED) visits has not been well discussed. This study aimed to compare the epidemiology and clinical characteristics of PED visits before and after the time of the COVID-19 outbreak. Methods Data of pediatric patients admitted to the PED between February 2019 and January 2021 were retrospectively collected. All patients were divided into two groups: 1 year before the COVID-19 pandemic (group 1) and 1 year after the COVID-19 outbreak (group 2). Basic demographics, clinical characteristics, triage levels, categories of diagnosis at PED, disposition, and hospitalization rates (wards and intensive care units) were further analyzed and compared between the two groups. Results During the study period, 48,146 pediatric patients were enrolled (30,823 in group 1, and 17,323 in group 2). PED visits represented a 43.8% annual decline. The most common diseases in the PED in group 1 were infectious diseases, whereas digestive system diseases were the most common diseases in group 2 (both P < 0.001). In group 2, shorter PED observational time, longer hospital stay, and higher admission rates were noted compared to those in group 1 (all P < 0.001). Conclusion During the COVID-19 pandemic, the proportion of respiratory system diseases and infectious diseases sharply decreased in the PED, whereas the proportion of digestive system diseases relatively increased. The COVID-19 pandemic has impacted the nature of PED visits and we should pay more attention on digestive system diseases and the rates of out-of-hospital cardiac arrest and overall mortality.

A bibliometric and visualized analysis of early mobilization in intensive care unit from 2000 to 2021

Background Early mobilization in the intensive care unit (ICU) is a hotspot. This study aims to provide a bibliometric perspective of the progress in this field. Methods We extracted publications on ICU early mobilization published in the Web of Science Core Collection database from 2000 to 2021. VOSviewer was used to construct co-occurrence and co-citation relationships for authors, references, and keywords;Citespace was used to visualize knowledge mapping of subject categories, countries, and keywords with the strongest citation bursts. Results A total of 4,570 publications were analyzed, with a steady increase in publications in the field of ICU early mobilization. From a macro perspective, research on ICU early mobilization involves multidisciplinary involvement, including critical care medicine, neurology, and nursing;as for the meso perspective, the United States is the major contributor. Needham DM and Schweickert WD are the key researchers in this field. Moreover, the core journal is Critical Care Medicine, with the most publications and citations. The microscopic level, dominated by references and keywords, illustrates that the hotspot and frontier of research on ICU early mobilization focus on ICU-acquired weakness, delirium, the prognosis of critical illness, and severe COVID-19. Conclusion This study presents a research landscape of ICU early mobilization from different perspectives. These findings will contribute to a better understanding of the current state of research in critical care medicine and provide the available information for future research ideas.

Evaluation of a Functional Single Nucleotide Polymorphism of the SARS-CoV-2 Receptor ACE2 That Is Potentially Involved in Long COVID

Since the occurrence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in December 2019, SARS-CoV-2 has led to a global coronavirus disease 2019 (COVID-19) pandemic. A better understanding of the SARS-CoV-2 receptor ACE2 at the genetic level would help combat COVID-19, particularly for long COVID. We performed a genetic analysis of ACE2 and searched for its common potential single nucleotide polymorphisms (SNPs) with minor allele frequency >0.05 in both European and Chinese populations that would contribute to ACE2 gene expression variation. We thought that the variation of the ACE2 expression would be an important biological feature that would strongly affect COVID-19 symptoms, such as “brain fog”, which is highlighted by the fact that ACE2 acts as a major cellular receptor for SARS-CoV-2 attachment and is highly expressed in brain tissues. Based on the human GTEx gene expression database, we found rs2106809 exhibited a significant correlation with the ACE2 expression among multiple brain and artery tissues. This expression correlation was replicated in an independent European brain eQTL database, Braineac. rs2106809*G also displays significantly higher frequency in Asian populations than in Europeans and displays a protective effect (p = 0.047) against COVID-19 hospitalization when comparing hospitalized COVID-19 cases with non-hospitalized COVID-19 or SARS-CoV-2 test-negative samples with European ancestry from the UK Biobank. Furthermore, we experimentally demonstrated that rs2106809*G could upregulate the transcriptional activity of ACE2. Therefore, integrative analysis and functional experiment strongly support that ACE2 SNP rs2106809 is a functional brain eQTL and its potential involvement in long COVID, which warrants further investigation.

Modelling and estimation of COVID-19 pandemic with the face mask and vaccination (preprint)

COVID-19 is a public health emergency for human beings and brings some very harmful consequences in social and economic fields. In order to model COVID-19 and develop the effective controlling measures, this paper proposes an SEIR-type epidemic model with the mask wearing and the vaccination. Firstly, the effective reproduction number and the threshold conditions are obtained by analyzing the dynamical behaviors of the proposed epidemic model.  Secondly, selecting the data of South Korea from January 20, 2022  to March 21, 2022, all model parameters are defined and estimated. Finally, based on the estimated parameters, the numerical simulations are conducted and the simulation suitably fit with the presented model. The results show that the  mask wearing ratio, the effectiveness of the certain face mask, the vaccination rate and effectiveness of vaccination for the susceptible individuals play an important role in preventing and controlling COVID-19 pandemic. The face mask wearing is associated with 83% and 90% reductions in the numbers of  the cumulative cases and the newly confirmed cases respectively after sixty days while the face mask wearing rate increases 15%, and the vaccination rate is associated with 75% and 80% reductions in the numbers of  the cumulative cases and the newly confirmed cases respectively after sixty days while the vaccination rate augments 15\%. Therefore,  the effect of  the mask wearing on reducing  the cumulative cases and the newly confirmed cases is more remarkable than that of the vaccination, this means the disease control departments should strongly recommended that peoples should wear the face mask to prevent themselves from becoming infected when the  vaccination willingness of individuals is relative low. The face mask wearing still the primary measure  to prevent and control the transmission of COVID-19 pandemic.

Investigation of Anti-Epithelial-Mesenchymal Transition and Anti-Inflammation effects of Qing Fei Hua Xian Decotion on Pulmonary Fibrosis via Network Pharmacology and Experimental Verification (preprint)

Background Pulmonary fibrosis (PF) is a common interstitial pneumonia disease, also occurred in post-COVID-19 survivors. The mechanism underlying the anti-PF effect of Qing Fei Hua Xian Decotion (QFHXD), a traditional Chinese medicine formula applied for treating PF in COVID-19 survivors, is unclear. This study aimed to uncover the mechanisms related to the anti-PF effect of QFHXD through analysis of network pharmacology and experimental verification.Methods The candidate chemical compounds of QFHXD and its putative targets for treating PF were achieved from public databases, thereby we established the corresponding “herb- compound -target” network of QFHXD. Moreover, The protein–protein interaction (PPI) network of potential targets was also constructed to screen the core targets. Furthermore, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to predict targets, and pathways, then validated by in vivo experiments.Results A total of 188 active compounds in QFHXD and 50 target genes were identified from databases. The key therapeutic targets of QFHXD, such as PI3K/Akt, IL-6, TNF, IL-1β, STAT3, MMP-9, and TGF-β1 were identified by KEGG and GO analysis. Anti-PF effects of QFHXD (in a dose-dependent manner) and prednisone were confirmed by HE, Masson staining, and Sirius red staining as well as in vivo Micro-CT and immunohistochemical analysis in a rat model of bleomycin-induced PF. Besides, QFXHD remarkably inhibits the activity of PI3K/Akt/NF-κB and TGF‑β1/Smad2/3.Conclusion QFXHD significantly attenuated bleomycin-induced PF via inhibiting inflammation and EMT. PI3K/Akt/NF-κB and TGF‑β1/Smad2/3 pathways might be the potential therapeutic effects of QFHXD for treating PF.

A cocktail containing two synergetic antibodies broadly neutralizes SARS-CoV-2 and its variants including Omicron BA.1 and BA.2 (preprint)

Neutralizing antibodies (NAbs) can prevent and treat infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, continuously emerging variants, such as Omicron, have significantly reduced the potency of most known NAbs. The selection of NAbs with broad neutralizing activities and the identification of conserved critical epitopes are still urgently needed. Here, we identified an extremely potent antibody (55A8) by single B-cell sorting from convalescent SARS-CoV-2-infected patients that recognized the receptor-binding domain (RBD) in the SARS-CoV-2 spike (S) protein. 55A8 could bind to wild-type SARS-CoV-2, Omicron BA.1 and Omicron BA.2 simultaneously with 58G6, a NAb previously identified by our group. Importantly, an antibody cocktail containing 55A8 and 58G6 (2-cocktail) showed synergetic neutralizing activity with a half-maximal inhibitory concentration (IC50) in the picomolar range in vitro and prophylactic efficacy in hamsters challenged with Omicron (BA.1) through intranasal delivery at an extraordinarily low dosage (25 g of each antibody daily) at 3 days post-infection. Structural analysis by cryo-electron microscopy (cryo-EM) revealed that 55A8 is a Class III NAb that recognizes a highly conserved epitope. It could block angiotensin-converting enzyme 2 (ACE2) binding to the RBD in the S protein trimer via steric hindrance. The epitopes in the RBD recognized by 55A8 and 58G6 were found to be different and complementary, which could explain the synergetic mechanism of these two NAbs. Our findings not only provide a potential antibody cocktail for clinical use against infection with current SARS-CoV-2 strains and future variants but also identify critical epitope information for the development of better antiviral agents.

Hetero-bivalent Nanobodies Provide Broad-spectrum Protection against SARS-CoV-2 Variants of Concern including Omicron (preprint)

Following Delta, Omicron variant triggered a new wave of SARS-CoV-2 infection globally, adaptive evolution of the virus may not stop, the development of broad-spectrum antivirals is still urgent. We previously developed two hetero-bivalent nanobodies with potent neutralization against original WT SARS-CoV-2, termed aRBD-2-5 and aRBD-2-7, by fusing aRBD-2 with aRBD-5 or aRBD-7, respectively. Here, we resolved crystal structures of these nanobodies in complex with RBD, and found the epitope of aRBD-2 differs from that of aRBD-5, aRBD-7. aRBD-2 binds to a conserved epitope which renders its binding activity to all variants of concern (VOCs) including Omicron. Interestingly, although monovalent aRBD-5 and aRBD-7 lost binding to some variants, they effectively improved the overall affinity when transformed into the hetero-bivalent form after being fused with aRBD-2. Consistent with the high binding affinities, aRBD-2-5-Fc and aRBD-2-7-Fc exhibited ultra-potent neutralization to all five VOCs; particularly, aRBD-2-5-Fc neutralized authentic virus of Beta, Delta and Omicron with the IC50 of 5.98~9.65 ng/mL or 54.3~87.6 pM. Importantly, aRBD-2-5-Fc provided in vivo prophylactic protection for mice against WT and mouse-adapted SARS-CoV-2, and provided full protection against Omicron in hamster model when administrated either prophylactically or therapeutically. Taken together, we found a conserved epitope on RBD, and hetero-bivalent nanobodies had increased affinity for VOCs over its monovalent form, and provided potent and broad-spectrum protection both in vitro and in vivo against all tested major variants, and potentially future emerging variants. Our strategy provides a new solution in the development of therapeutic antibodies for COVID-19 caused by newly emergent VOCs.

Omicron-specific mRNA vaccine elicits potent immune responses in mice, hamsters, and nonhuman primates (preprint)

SARS-CoV-2 has infected more than 400 million people around the globe and caused millions of deaths. Since its identification in November 2021, Omicron, a highly transmissible variant, has become the dominant variant in most countries. Omicron highly mutated spike protein, the main target of vaccine development, significantly compromises the immune protection from current vaccination. We develop an mRNA vaccine (SOmicron-6P) based on an Omicron-specific sequence. In mice, SOmicron-6P shows superior neutralizing antibodies inducing abilities to a clinically approved inactivated virus vaccine, a clinically approved protein subunit vaccine, and an mRNA vaccine (SWT-2P) with the same sequence of BNT162b2 RNA. Significantly, SOmicron-6P induces a 14.4~27.7-fold and a 28.3~50.3-fold increase of neutralizing activity against the pseudovirus of Omicron and authentic Omicron compared to SWT-2P, respectively. In addition, two doses SOmicron-6P significantly protects Syrian hamsters against challenge with SARS-CoV-2 Omicron variant and elicits high titers of nAbs in a dose-dependent manner in macaques. Our results suggest that SOmicron-6P offers advantages over current vaccines, and it will be helpful for those with weak immunity.

COVID-19 excess death rate in Eastern European countries associated with weaker regulation implementation and lower vaccination coverage (preprint)

Abstract Aim: The objective of this analysis was to assess the association of excess COVID-19 mortality with regulation enforcement and vaccination rate in selected countries. Methods: This analysis included 50 countries pertinent to the WHO European Region, in addition to USA and Canada. Excess mortality and vaccination data were retrieved from Our World In Data database, while regulation implementation was measured from a well-respected, standardized measure. Outpatient visits were also included in the analysis. Multiple linear regression was used to assess the independent association between excess mortality and each covariate. Results: Excess mortality increased by 4.1/100 000 for every percent decrease in vaccination rate and with 6/100 000 for every decreased unit in the regulatory implementation score a country achieved in the Rule of Law Index. Conclusion: Degree of regulation enforcement, likely including public health measure enforcement, may be an important factor in controlling COVID-19s deleterious health impacts.

A mathematical model reveals the influence of NPIs and vaccination on SARS-CoV-2 Omicron Variant (preprint)

A SVEIR SARS-CoV-2 Omicron variant model is proposed to provide some insight to coordinate non-pharmaceutical interventions(NPIs) and vaccination. Mathematically, we define the basic reproduction number R0 and the effective reproduction number Re to measure the infection potential of Omicron variant and formulate a optimal disease control strategy. Our inversion results imply that the sick period of Omicron variant in the United States is longer than that of Delta variant in Indian; The decreasing of the infectious period of the infection with infectiousness implies that the risk of hospitalization is reduced; but the increasing period of the infection with non-infectiousness signifies that Omicron variant lengthens the period of nucleic acid test being negative; Optimistically, Omicron's death rate is only a quarter of Delta's. Moreover, we forecast that the cumulative cases will exceed 100 million in the United States on 28 February, 2022 and the daily confirmed cases will reach a peak on 2 February, 2022. The results of parameters sensitivity analysis imply that NPIs is helpful to reduce the number of confirmed cases. Especially, NPIs are indispensable even if all the people were vaccinated when the efficiency of vaccine is relatively low. By simulating the relation ships of the effective reproduction number Re , the vaccination rate and the efficacy of vaccine, we find that it is impossible to achieve the herd immunity without NPIs while the efficiency of vaccine is lower than 88.7%. Therefore, the herd immunity area is defined by the evolution of relationships between the vaccination rate and the efficacy of vaccine. Finally, we present that the disease-induced mortality rate demonstrates the periodic oscillation and an almost periodic function is deduced to match the curve. A discussion completes the paper.AMS Subject Classification (2020): 34A34; 34D20; 92D30

Harringtonine has the effects of double blocking SARS-CoV-2 membrane fusion (preprint)

Fusion with host cell membrane is the main mechanism of infection of SARS-CoV-2. Here, we propose a new strategy to double block SARS-CoV-2 membrane fusion by using Harringtonine (HT), a small-molecule antagonist. By using cell membrane chromatography (CMC), we found that HT specifically targeted the SARS-CoV-2 S protein and host cell TMPRSS2, and then confirmed that HT can inhibit pseudotyped virus membrane fusion. Furthermore, HT successfully blocked SARS-CoV-2 infection, especially in the delta and Omicron mutant. Since HT is a small-molecule antagonist, it is minimally affected by the continuous variation of SARS-CoV-2. Our findings show that HT is a potential small-molecule antagonist with a new mechanism of action against SARS-CoV-2 infection, and thus HT mainly targets the S protein, and thus, greatly reduces the damage of the S protein's autotoxicity to the organ system, has promising advantages in the clinical treatment of COVID-19.

Chinese Parent Intention to Vaccinate Children With Special Diseases Against COVID-19.

Background: Information on the intention of parents of children with special diseases to vaccinate their children against coronavirus disease 2019 (COVID-19) is scarce. Methods: In this survey, all participants (n = 914) were enrolled from a tertiary children's hospital between September 2020 and April 2021. A face-to-face questionnaire interview was conducted to collect information on the special diseases of children and parental attitudes about the COVID-19 vaccine. We compared the demographic and disease factors between the group of parents who were willing to vaccinate their children against COVID-19 and the group who were unwilling to vaccinate. Results: Among 941 children, 58.1% (n = 547) were boys. The Mean age was 1.4 (SD 1.9) years. If the COVID-19 vaccine becomes available for the child, 470 (49.9%) of parents were willing to provide vaccination for their children. The less the education levels of the father or mother, the more likely they were to vaccinate their children (P = 0.003, P = 0.007). However, more intentions to vaccinate were provided in parents of children with COVID-19 prevention and control education (P < 0.001). Conclusion: Our findings provided evidence that some parents are willing to vaccinate their children with special diseases against COVID-19. Professional knowledge about COVID-19 prevention and control may contribute to increased parental intention.

Structure selected RBM immunogens prime polyclonal memory responses that neutralize SARS-CoV-2 variants of concern (preprint)

Successful control of the COVID-19 pandemic depends on vaccines that prevent transmission. The full-length Spike protein is highly immunogenic but the majority of antibodies do not target the virus: ACE2 interface. In an effort to concentrate the antibody response to the receptor-binding motif (RBM) we generated a series of conformationally-constrained immunogens by inserting solvent-exposed RBM amino acid residues into hypervariable loops of an immunoglobulin molecule. Priming C57BL/6 mice with plasmid (p)DNA encoding these constructs yielded a rapid memory response to booster immunization with recombinant Spike protein. Immune sera antibodies bound strongly to the purified receptor-binding domain (RBD) and Spike proteins. pDNA primed for a consistent response with antibodies efficient at neutralizing authentic WA1 virus and two variants of concern (VOC), B.1.351 and B.1.617.2. These findings demonstrate that immunogens built on structure selection can focus the response to conserved sites of vulnerability shared between wildtype virus and VOCs and induce neutralizing antibodies across variants.

Single-dose AAV-based vaccine induces a high level of neutralizing antibodies and provides long-term protection against SARS-CoV-2 in rhesus macaques (preprint)

Coronavirus disease 2019 (COVID-19), which is triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, continues to threaten global public health. Developing a vaccine that only requires single immunization but provides long-term protection for the prevention and control of COVID-19 is important. Here, we developed an adeno-associated virus (AAV)-based vaccine expressing a stable receptor-binding domain (SRBD) protein. The vaccine requires only a single shot but provides effective neutralizing antibodies (NAbs) over 598 days in rhesus macaques (Macaca mulatta). Importantly, our results showed that the NAbs were kept in high level and long lasting against authentic wild-type SARS-CoV-2, Beta, Delta and Omicron variants using plaque reduction neutralization test. Of note, although we detected pre-existing AAV2/9 antibodies before immunization, the vaccine still induced high and effective NAbs against COVID-19 in rhesus macaques. AAV-SRBD immune serum also efficiently inhibited the binding of ACE2 with RBD in the SARS-CoV-2 B.1.1.7 (Alpha), B.1.351 (Beta), P.1/P.2 (Gamma), B.1.617.2 (Delta), B.1.617.1/3(Kappa), and C.37 (Lambda) variants. Thus, these data suggest that the vaccine has great potential to prevent the spread of SARS-CoV-2.