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

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 summaryA 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.

CD147 antibody specifically and effectively inhibits infection and cytokine storm of SARS-CoV-2 variants

SARS-CoV-2 and its variants are raging worldwide. Unfortunately, the global vaccination is not efficient enough to attain a vaccine-based herd-immunity and yet no special and effective drug is developed to contain the spread of the disease. Previously we have identified CD147 as a novel receptor for SARS-CoV-2 infection. Here, we demonstrated that CD147 antibody effectively inhibits infection and cytokine storm caused by SARS-CoV-2 variants. In CD147KO VeroE6 cells, infections of SARS-CoV-2, its variants (B.1.1.7, B.1.351) and pseudovirus mutants (B.1.1.7, B.1.351, B.1.525, B.1.526 (S477N), B.1.526 (E484K), P.1, P.2, B.1.617.1, B.1.617.2) were decreased. Meanwhile, CD147 antibody effectively blocked the entry of variants and pseudomutants in VeroE6 cells, and inhibited the expression of cytokines. A model of SARS-CoV-2-infected hCD147 transgenic mice was constructed, which recapitulated the features of exudative diffuse alveolar damage and dynamic immune responses of COVID-19. CD147 antibody could effectively clear the virus and alveolar exudation, resolving the pneumonia. We found the elevated level of cyclophilin A (CyPA) in plasma of severe/critical cases, and identified CyPA as the most important proinflammatory intermediate causing cytokine storm. Mechanistically, spike protein of SARS-CoV-2 bound to CD147 and initiated the JAK-STAT pathway, which induced expression of CyPA. CyPA reciprocally bound to CD147, triggered MAPK pathway and consequently mediated the expression of cytokine and chemokine. In conclusion, CD147 is a critical target for SARS-CoV-2 variants and CD147 antibody is a promising drug to control the new wave of COVID-19 epidemic.

GP73 is a glucogenic hormone regulating SARS-CoV-2-induced hyperglycemia

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection induces new-onset diabetes and severe metabolic complications of pre-existing diabetes. The pathogenic mechanism underlying this is incompletely understood. Here, we provided evidence linking circulating GP73 with the exaggerated gluconeogenesis triggered by SARS-CoV-2 infection. We found that SARS-CoV-2 infection or glucotoxic condition increased the cellular secretion of GP73. Secreted GP73 trafficked to the liver and kidney to stimulate gluconeogenesis through cAMP/PKA pathway. By using global phosphoproteomics, we found a drastic remodeling of PKA kinase hub exerted by GP73. Notably, COVID-19 patients showed pathologically elevated plasma GP73, and neutralization of the secreted GP73 inhibited enhanced PKA signaling and glucose production associated with SARS-CoV-2 infection. GP73 blockade also reduced gluconeogenesis and lowered hyperglycemia in type 2 (T2D) diabetic mice. Therefore, our findings provide novel insight into the roles of GP73 as a key glucogenic hormone and mechanistic clues underlying the development of SARS-CoV-induced glucose abnormalities.

Recombinant Fc-fusion vaccine of RBD induced protection against SARS-CoV-2 in non-human primate and mice

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) continues to infect people globally. The increased COVID-19 cases and no licensed vaccines highlight the need to develop safe and effective vaccines against SARS-CoV-2 infection. Multiple vaccines candidates are under pre-clinical or clinical trails with different strengths and weaknesses. Here we developed a pilot scale production of a recombinant subunit vaccine (RBD-Fc Vacc) with the Receptor Binding Domain of SARS-CoV-2 S protein fused with the Fc domain of human IgG1. RBD-Fc Vacc induced SARS-CoV-2 specific neutralizing antibodies in non-human primates and human ACE2 transgenic mice. The antibodies induced in macaca fascicularis neutralized three divergent SARS-CoV2 strains, suggesting a broader neutralizing ability. Three times immunizations protected Macaca fascicularis (20ug or 40ug per dose) and mice (10ug or 20ug per dose) from SARS-CoV-2 infection respectively. These data support clinical development of SARS-CoV-2 vaccines for humans. RBD-Fc Vacc is currently being assessed in randomized controlled phase 1/II human clinical trails. SummaryThis study confirms protective efficacy of a SARS-CoV-2 RBD-Fc subunit vaccine.

A proof of concept for neutralizing antibody-guided vaccine design against SARS-CoV-2

Mutations and transient conformational movements of receptor binding domain (RBD) that make neutralizing epitopes momentarily unavailable, present immune escape routes to SARS-CoV-2. To mitigate viral escape, we developed a cocktail of neutralizing antibodies (NAbs) targeting epitopes located on different domains of spike (S) protein. Screening of a library of monoclonal antibodies generated from peripheral blood mononuclear cells of COVID-19 convalescent patients yielded potent NAbs, targeting N-terminal domain (NTD) and RBD domain of S, effective at nM concentrations. Remarkably, combination of RBD-targeting NAbs and NTD-binding NAb, FC05, dramatically enhanced the neutralization potency in cell-based assays and animal model. Results of competitive SPR assays and cryo-EM structures of Fabs bound to S unveil determinants of immunogenicity. Combinations of immunogens, identified in NTD and RBD of S, when immunized in rabbits elicited potent protective immune responses against SARS-CoV-2. These results provide a proof-of-concept for neutralization-based immunogen design targeting SARS-CoV-2 NTD and RBD. One sentence summaryImmunogens identified in the NTD and RBD of the SARS-CoV-2 spike protein using a cocktail of non-competing NAbs when injected in rabbits elicited a potent protective immune response against SARS-CoV-2.

Stability of SARS-CoV-2 on environmental surfaces and in human excreta

At room temperature, SARS-CoV-2 was stable on environmental surfaces and remained viable up to 7 days on smooth surfaces. This virus could survive for several hours in feces and 3-4 days in urine.

Structure-based drug design, virtual screening and high-throughput screening rapidly identify antiviral leads targeting COVID-19

A new coronavirus (CoV) identified as COVID-19 virus is the etiological agent responsible for the 2019-2020 viral pneumonia outbreak that commenced in Wuhan1-4. Currently there is no targeted therapeutics and effective treatment options remain very limited. In order to rapidly discover lead compounds for clinical use, we initiated a program of combined structure-assisted drug design, virtual drug screening and high-throughput screening to identify new drug leads that target the COVID-19 virus main protease (Mpro). Mpro is a key CoV enzyme, which plays a pivotal role in mediating viral replication and transcription, making it an attractive drug target for this virus5,6. Here, we identified a mechanism-based inhibitor, N3, by computer-aided drug design and subsequently determined the crystal structure of COVID-19 virus Mpro in complex with this compound. Next, through a combination of structure-based virtual and high-throughput screening, we assayed over 10,000 compounds including approved drugs, drug candidates in clinical trials, and other pharmacologically active compounds as inhibitors of Mpro. Six of these inhibit Mpro with IC50 values ranging from 0.67 to 21.4 M. Ebselen also exhibited promising antiviral activity in cell-based assays. Our results demonstrate the efficacy of this screening strategy, which can lead to the rapid discovery of drug leads with clinical potential in response to new infectious diseases where no specific drugs or vaccines are available.

Construction and characterization of recombinant pseudovirus particles carrying specific genomic RNA of St.Louis encephalitis virus / 军事医学

Objective To prepare quality control samples for St.Louis encephalitis virus(SLEV)molecular detection by constructing pseudovirus containing target sequences of SLEV.Methods According to the principles of armored RNA technique, the prM gene sequence of SLEV was cloned into the prokaryotic expression vector to generate recombinant plasmid pSE380-MS2-SLEV.Then, recombinant E.coli transformed with the corresponding plasmid was induced with IPTG to produce recombinant pseudovirus particles.The particles were purified by chloroform and further characterized by double enzyme digestion and transmission electron microscopy.The temperature sensitivity experiments and quantitative RT-PCR were performed to validate the potential of these pseudovirus particles as quality control samples.Results PCR amplification and sequencing analysis confirmed that the prM gene sequence of SLEV was cloned into vector pSE380-MS2.Transmission electron microscopy showed that homogenous spherical particles with a diameter of about 25 nm were produced upon IPTG induction.The SLEV genomic RNA within the pseudovirus particles was resistant to DNaseⅠand RNase A digestion, and remained stable for 20 days at 37℃.These samples were validated with quantitative RT-PCR for SLEV.Conclusion The RNase-resistant and stable pseudovirus particles containing prM fragment of SLEV are constructed successfully, which can be used as positive quality control samples for RNA extraction and molecular detection.

Advances in research on enterovirus 71 vaccines / 军事医学

Enterovirus 71 (EV71) is one of the primary causative agents of hand, foot and mouth disease in children and closely associated with severe neurological complications and even deaths.EV71 outbreaks have occurred throughout the Asia-Pacific region since 1990s, posing global public health threat;however, no specific therapeutic strategy exists for severe EV71 infection.Several inactivated vaccine products have entered or finished the clinical trial stage, and some novel vaccine candidates, including live attenuated, subunit, and virus-like particle, show great potential for further develop-ment.This review summarizes the present situation and progress in the development of EV71 vaccines.

Simultaneous infection with dengue 2 and 3 viruses in a Chinese patient return from Sri Lanka.

Dengue is an acute viral disease transmitted by the Aedes aegypti and Aedes albopictus mosquito, which are present in most tropical urban areas of the world. There are four antigenically distinct serotypes, designated dengue-1 (DEN-1), dengue-2 (DEN-2), dengue-3 (DEN-3) and dengue-4 (DEN-4). Dengue outbreaks have occurred in several regions in Asia, involving four serotypes of dengue 1, 2, 3 and 4. In review of the few cases of dual infection documented in the literature, we report here a case of simultaneous infection with DEN-2 and DEN-3 in a Chinese patient return from Sri Lanka. The dual infection was identified by type-specific indirect immunofluorescence assay and confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and sequence determination. This is the first documented case of simultaneous infection with serotype of DEN-2 and DEN-3 in China.

Complete genome sequences of the SARS-CoV: the BJ Group (Isolates BJ01-BJ04) / 基因组蛋白质组与生物信息学报·英文版

Beijing has been one of the epicenters attacked most severely by the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) since the first patient was diagnosed in one of the city's hospitals. We now report complete genome sequences of the BJ Group, including four isolates (Isolates BJ01, BJ02, BJ03, and BJ04) of the SARS-CoV. It is remarkable that all members of the BJ Group share a common haplotype, consisting of seven loci that differentiate the group from other isolates published to date. Among 42 substitutions uniquely identified from the BJ group, 32 are non-synonymous changes at the amino acid level. Rooted phylogenetic trees, proposed on the basis of haplotypes and other sequence variations of SARS-CoV isolates from Canada, USA, Singapore, and China, gave rise to different paradigms but positioned the BJ Group, together with the newly discovered GD01 (GD-Ins29) in the same clade, followed by the H-U Group (from Hong Kong to USA) and the H-T Group (from Hong Kong to Toronto), leaving the SP Group (Singapore) more distant. This result appears to suggest a possible transmission path from Guangdong to Beijing/Hong Kong, then to other countries and regions.

Research Advancement in Gas-phase Pollutant Treatment by Photocatalytic Oxidation / 环境与健康杂志

Much attention has been paid to photocatalytic oxidation in the field of air and water purification. Photocatalytic oxidation employs semiconductors such as TiO2, ZnO as a photocatalyst in ultraviolet radiation. Several factors which affect photocatalytic decomposition were discussed in the present paper. Photocatalytic oxidation technique is applicable for the elimination of gas-phase contamination in air.