The Impact of Mutations in SARS-CoV-2 Spike on Viral Infectivity and Antigenicity.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the global COVID-19 pandemic. Rapidly spreading SARS-CoV-2 variants may jeopardize newly introduced antibody and vaccine countermeasures. Here, using monoclonal antibodies (mAbs), animal immune sera, human convalescent sera and human sera from recipients of the BNT162b2 mRNA vaccine, we report the impact on antibody neutralization of a panel of authentic SARS-CoV-2 variants including a B.1.1.7 isolate, chimeric strains with South African or Brazilian spike genes and isogenic recombinant viral variants. Many highly neutralizing mAbs engaging the receptor-binding domain or N-terminal domain and most convalescent sera and mRNA vaccine-induced immune sera showed reduced inhibitory activity against viruses containing an E484K spike mutation. As antibodies binding to spike receptor-binding domain and N-terminal domain demonstrate diminished neutralization potency in vitro against some emerging variants, updated mAb cocktails targeting highly conserved regions, enhancement of mAb potency or adjustments to the spike sequences of vaccines may be needed to prevent loss of protection in vivo.

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Resistance of SARS-CoV-2 variants to neutralization by monoclonal and serum-derived polyclonal antibodies.

N-terminal domain antigenic mapping reveals a site of vulnerability for SARS-CoV-2.

The past several months have witnessed the emergence of SARS-CoV-2 variants with novel spike protein mutations that are influencing the epidemiological and clinical aspects of the COVID-19 pandemic. These variants can increase rates of virus transmission and/or increase the risk of reinfection and reduce the protection afforded by neutralizing monoclonal antibodies and vaccination. These variants can therefore enable SARS-CoV-2 to continue its spread in the face of rising population immunity while maintaining or increasing its replication fitness. The identification of four rapidly expanding virus lineages since December 2020, designated variants of concern, has ushered in a new stage of the pandemic. The four variants of concern, the Alpha variant (originally identified in the UK), the Beta variant (originally identified in South Africa), the Gamma variant (originally identified in Brazil) and the Delta variant (originally identified in India), share several mutations with one another as well as with an increasing number of other recently identified SARS-CoV-2 variants. Collectively, these SARS-CoV-2 variants complicate the COVID-19 research agenda and necessitate additional avenues of laboratory, epidemiological and clinical research.

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The biological and clinical significance of emerging SARS-CoV-2 variants.

The emergence of the highly transmissible B.1.1.529 Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is concerning for antibody countermeasure efficacy because of the number of mutations in the spike protein. In this study, we tested a panel of anti-receptor-binding domain monoclonal antibodies (mAbs) corresponding to those in clinical use by Vir Biotechnology (S309, the parent mAb of VIR-7831 (sotrovimab)), AstraZeneca (COV2-2196 and COV2-2130, the parent mAbs of AZD8895 and AZD1061), Regeneron (REGN10933 and REGN10987), Eli Lilly (LY-CoV555 and LY-CoV016) and Celltrion (CT-P59) for their ability to neutralize an infectious B.1.1.529 Omicron isolate. Several mAbs (LY-CoV555, LY-CoV016, REGN10933, REGN10987 and CT-P59) completely lost neutralizing activity against B.1.1.529 virus in both Vero-TMPRSS2 and Vero-hACE2-TMPRSS2 cells, whereas others were reduced (COV2-2196 and COV2-2130 combination, ~12-fold decrease) or minimally affected (S309). Our results suggest that several, but not all, of the antibodies in clinical use might lose efficacy against the B.1.1.529 Omicron variant. 

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An infectious SARS-CoV-2 B.1.1.529 Omicron virus escapes neutralization by therapeutic monoclonal antibodies

Improved Dynamic Event-Triggered Anti-Unwinding Control for Autonomous Underwater Vehicles

The invention relates to a DNA (Deoxyribose Nucleic Acid)-based infectious clone of a Japanese encephalitis virus SA14-14-2 strain and a construction method of the infectious clone The infectious clone is constructed by adopting a pBR322 plasmid as a framework vector and then inserting the full-length cDNA of the Japanese encephalitis virus SA14-14-2 vaccine strain; the 5' end of the full-length cDNA of the SA214-14-2 vaccine strain is connected with a CMV (Cucumber Mosaic Virus) promoter, a BGH (Bovine Growth Hormone) polyadenylation sequence is added at the 3' end, and gomphosis intron sequences for stabilizing are respectively added on the 356 locus and the 2217 locus of the genome cDNA The invention also provides application of infectious clone serving as a novel viral vector, and thus a solid foundation is provided for developing a plurality of novel vaccines for preventing and treating tumours and viral diseases

DNA (Deoxyribose Nucleic Acid)-based infectious clone of a Japanese encephalitis virus SA14-14-2 strain, as well as construction method and application thereof

The development of a safe and effective vaccine is a key requirement to overcoming the COVID-19 pandemic. Recombinant proteins represent the most reliable and safe vaccine approach but generally require a suitable adjuvant for robust and durable immunity. We used the SARS-CoV-2 genomic sequence and in silico structural modelling to design a recombinant spike protein vaccine (Covax-19). A synthetic gene encoding the spike extracellular domain (ECD) was inserted into a baculovirus backbone to express the protein in insect cell cultures. The spike ECD was formulated with Advax-SM adjuvant and first tested for immunogenicity in C57BL/6 and BALB/c mice. The Advax-SM adjuvanted vaccine induced high titers of binding antibody against spike protein that were able to neutralise the original wildtype virus on which the vaccine was based as well as the variant B.1.1.7 lineage virus. The Covax-19 vaccine also induced potent spike-specific CD4+ and CD8+ memory T-cells with a dominant Th1 phenotype, and this was shown to be associated with cytotoxic T lymphocyte killing of spike labelled target cells in vivo. Ferrets immunised with Covax-19 vaccine intramuscularly twice 2 weeks apart made spike receptor binding domain (RBD) IgG and were protected against an intranasal challenge with SARS-CoV-2 virus 2 weeks after the second immunisation. Notably, ferrets that received two 25 or 50g doses of Covax-19 vaccine had no detectable virus in their lungs or in nasal washes at day 3 post-challenge, suggesting the possibility that Covax-19 vaccine may in addition to protection against lung infection also have the potential to block virus transmission. This data supports advancement of Covax-19 vaccine into human clinical trials.

https://www.biorxiv.org/content/biorxiv/early/2021/07/05/2021.07.03.451026.full.pdf

Immunisation of ferrets and mice with recombinant SARS-CoV-2 spike protein formulated with Advax-SM adjuvant protects against COVID-19 infection

One DRV strain was isolated from Sika Deer brain and sequenced. Nine overlapped gene fragments were amplified by RT-PCR through 3'-RACE and 5'-RACE method, and the complete DRV genome sequence was assembled. The length of the complete genome is 11863bp. The DRV genome organization was similar to other rabies viruses which were composed of five genes and the initiation sites and termination sites were highly conservative. There were mutated amino acids in important antigen sites of nucleoprotein and glycoprotein. The nucleotide and amino acid homologies of gene N, P, M, G, L in strains with completed genomie sequencing were compared. Compared with N gene sequence of other typical rabies viruses, a phylogenetic tree was established . These results indicated that DRV belonged to gene type 1. The highest homology compared with Chinese vaccine strain 3aG was 94%, and the lowest was 71% compared with WCBV. These findings provided theoretical reference for further research in rabies virus.

Ying Huang

Papers

Improved Dynamic Event-Triggered Anti-Unwinding Control for Autonomous Underwater Vehicles

DNA (Deoxyribose Nucleic Acid)-based infectious clone of a Japanese encephalitis virus SA14-14-2 strain, as well as construction method and application thereof

Immunisation of ferrets and mice with recombinant SARS-CoV-2 spike protein formulated with Advax-SM adjuvant protects against COVID-19 infection

Sequencing and Analysis of the Complete Genome of a Rabies Virus Isolate from Sika Deer

Distributed event-triggered affine formation control for multiple underactuated marine surface vehicles