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The Omicron variant of SARS-CoV-2 (B.
1.
1.
529.
1 or BA.
1) was discovered by iNature in Botswana in November 2021
.
Continued monitoring of Omicron evolution since then has revealed increased prevalence of two sublineages, BA.
1 with the R346K mutation (BA.
1+R346K, also known as BA.
1.
1) and B.
1.
1.
529.
2 (BA.
2), Having the latter contains unique spike mutations, but lacks the 13 spike mutations found in BA.
1
.
On March 3, 2022, a research paper titled "Antibody evasion properties of SARS-CoV-2 Omicron sublineages" was published online by Columbia University's Dayi Ho team in Nature.
The study found that patients with wild-type SARS-CoV-2 infection or Polyclonal sera from recipients of the current mRNA vaccine showed a significant loss of neutralizing activity against BA.
1+R346K and BA.
2, a decrease comparable to that reported for BA.
1
.
These findings suggest that these three Omicron sublineages are antigenically equidistant from wild-type SARS-CoV-2 and thus similarly threaten the efficacy of current vaccines
.
BA.
2 also exhibited significant resistance to 17 of 19 neutralizing mAbs, including S309 (sotrovimab), which retained significant activity against BA.
1 and BA.
1+R346K
.
Taken together, this new finding demonstrates that, with the exception of the recently licensed LY-CoV1404 (bebtelovimab), no licensed monoclonal antibody therapy adequately covers all sublineages of Omicron variants
.
In addition, on February 28, 2022, Cong Yao, Wang Yanxing, Center for Excellence in Molecular and Cell Science, Chinese Academy of Sciences, and Huang Zhong, Pasteur Institute, Shanghai, Chinese Academy of Sciences, published a joint communication titled "Molecular basis of receptor binding and antibody neutralization in Nature online.
of Omicron", which showed the closed and open states of Omicron spikes (S) by cryo-EM analysis, which appear to be more compact than their counterparts of the G614 strain, possibly indicating conformational masking of Omicron immune evasion mechanism
.
This study captures three states of the Omicron S-ACE2 complex, revealing that substitution on the Omicron RBM leads to new salt bridges/hydrogen bonds, more favorable electrostatic surface properties, and an overall enhanced S-ACE2 interaction, consistent with the observed Omicron S has higher ACE2 affinity relative to G614
.
Furthermore, this study determined the structure of Omicron S complexed with the Fab of S3H3, an antibody capable of cross-neutralizing variants of prime interest including Omicron, elucidating the structural basis for S3H3-mediated broad-spectrum neutralization
.
The findings shed new light on receptor engagement and antibody neutralization/evasion of Omicron and may also inform the design of broadly effective SARS-CoV-2 vaccines
.
On February 8, 2022, Science published a collaboration between the team of Xu Huaqiang/Yin Wanchao from Shanghai Institute of Materia Medica, Chinese Academy of Sciences, and the team of Jimin Xinxin Deng Sujun, entitled "Structures of the Omicron Spike trimer with ACE2 and an anti-Omicron antibody.
"The latest achievement, the study analyzed the spike protein of the poisonous Omicron mutant strain, and the high-resolution cryo-electron microscope structure that binds to its receptor ACE2 and the broad-spectrum anti-COVID-19 antibody JMB2002, respectively.
The molecular mechanism of rapid spread and immune escape of mutant strains, and revealed a new mechanism of action of the therapeutic antibody JMB2002, providing new ideas for the design and development of broad-spectrum anti-COVID-19 antibodies (click to read)
.
On January 21, 2022, the research team of Zhu Xuan/Chen Fuhe/Yuan Guoyong of the University of Hong Kong and the research team of the Key Laboratory of Tropical Translational Medicine, Hainan Medical College, Ministry of Education, jointly published a paper entitled "Attenuated replication and pathogenicity of SARS-CoV in Nature online.
-2 B.
1.
1.
529 Omicron" research paper showing that replication of Omicron variants is significantly attenuated in Calu3 and Caco2 cells
.
Further mechanistic studies revealed that the Omicron variant was inefficient in the use of transmembrane serine protease 2 (TMPRSS2) compared to the WT and previous variants, which could explain its reduced replication in Calu3 and Caco2 cells
.
Omicron replication in the upper and lower airways of infected K18-hACE2 mice was significantly attenuated compared to WT and Delta variants, which resulted in a significant improvement in their lung pathology
.
Omicron variant infection resulted in minimal weight loss and mortality compared to SARS-CoV-2 WT, Alpha, Beta and Delta variants
.
Overall, this study shows that the Omicron variant has attenuated viral replication and pathogenicity in mice compared to WT and previous variants (click to read)
.
On January 5, 2022, Wang Peiyi of Southern University of Science and Technology, Gao Fu and Qi Jianxun of the Institute of Microbiology, Chinese Academy of Sciences published a joint communication in Cell Online entitled "Receptor binding and complex structures of human ACE2 to spike RBD from Omicron and Delta SARS-CoV-2 ” research paper, which explored the binding properties between the human receptor ACE2 (hACE2) and VOC RBD, and solved the crystal and cryo-EM structures of the Omicron RBD-hACE2 complex and the Delta RBD-hACE2 complex
.
The study found that, unlike Alpha, Beta, and Gamma, Omicron RBD had similar binding affinity to hACE2 compared to prototypic RBD, likely due to the compensation of multiple mutations for immune escape and transmissibility
.
The complex structures of Omicron-hACE2 and Delta-hACE2 reveal the structural basis for how RBD-specific mutations bind to hACE2 (click to read)
.
Receptor binding is a critical step in viral invasion
.
Similar to SARS CoV, SARS-CoV-2 uses its spike (S) protein to recognize the host receptor ACE2
.
The C-terminal domain (CTD) of the S protein, also known as the receptor binding domain (RBD), is responsible for ACE2 recognition and is an important determinant of host range
.
In addition, the S protein is the primary target of neutralizing antibodies
.
Mutations in the S protein, especially RBD, may lead to immune escape and disrupt the efficacy of current therapies and vaccines
.
Due to continued global spread, SARS-CoV-2 continues to evolve into new variants
.
Variants with evidence of increased infectivity, severe disease, reduced antibody neutralization in recovered individuals or vaccines, and a higher risk of evading detection were classified as variants of interest (VOC)
.
Currently, the World Health Organization (WHO) has announced five VOCs, namely Alpha, Beta, Gamma, Delta and the recently identified Omicron
.
The study reported that VOCs, especially the Beta variant, experienced immune escape when treated with most clinically available monoclonal antibodies
.
There have also been reports of compromised protective efficacy of currently licensed vaccines against previous VOCs, although the reduction in efficacy has been quite mild
.
Delta VOC was shown to have a higher transmission rate, which could be explained by its higher replication rate and S-mediated entry
.
Article pattern diagram (image from Cell) Unlike other VOCs that appear when innate immunity prevails, Omicron appears in the context of widespread vaccination against SARS-CoV-2
.
Genome sequencing revealed that Omicron carries an unusually high number of mutations, especially in the S protein (23 amino acid substitutions) and its RBD (15 amino acid substitutions)
.
Putative analyses suggest that some mutations are associated with enhanced viral transmission, infectivity, and immune evasion
.
Recent studies have shown that Omicron can escape abundantly from neutralizing antibodies and sera from convalescent patients or from people vaccinated with Pfizer's vaccine BNT162b2
.
Unraveling the molecular mechanisms of VOC receptor recognition is critical to understanding the impact of Omicron on infection, transmission, and immune escape
.
In this study, several VOCs were examined, including Alpha, Beta, Gamma, Delta, and Omicron, and it was demonstrated that the Omicron variant RBD binds hACE2 with comparable affinity to the prototype
.
The study then determined the crystal and cryo-EM structures of Omicron RBD in complex with hACE2 and identified the role of key residues in receptor recognition
.
Furthermore, this study solved the crystal structure of the Delta RBD-hACE2 complex
.
The findings provide important molecular information about Omicron and Delta VOC and may guide the development of novel preventive/therapeutic approaches targeting major Omicron variants
.
Reference message: https://#relatedArticles
1.
1.
529.
1 or BA.
1) was discovered by iNature in Botswana in November 2021
.
Continued monitoring of Omicron evolution since then has revealed increased prevalence of two sublineages, BA.
1 with the R346K mutation (BA.
1+R346K, also known as BA.
1.
1) and B.
1.
1.
529.
2 (BA.
2), Having the latter contains unique spike mutations, but lacks the 13 spike mutations found in BA.
1
.
On March 3, 2022, a research paper titled "Antibody evasion properties of SARS-CoV-2 Omicron sublineages" was published online by Columbia University's Dayi Ho team in Nature.
The study found that patients with wild-type SARS-CoV-2 infection or Polyclonal sera from recipients of the current mRNA vaccine showed a significant loss of neutralizing activity against BA.
1+R346K and BA.
2, a decrease comparable to that reported for BA.
1
.
These findings suggest that these three Omicron sublineages are antigenically equidistant from wild-type SARS-CoV-2 and thus similarly threaten the efficacy of current vaccines
.
BA.
2 also exhibited significant resistance to 17 of 19 neutralizing mAbs, including S309 (sotrovimab), which retained significant activity against BA.
1 and BA.
1+R346K
.
Taken together, this new finding demonstrates that, with the exception of the recently licensed LY-CoV1404 (bebtelovimab), no licensed monoclonal antibody therapy adequately covers all sublineages of Omicron variants
.
In addition, on February 28, 2022, Cong Yao, Wang Yanxing, Center for Excellence in Molecular and Cell Science, Chinese Academy of Sciences, and Huang Zhong, Pasteur Institute, Shanghai, Chinese Academy of Sciences, published a joint communication titled "Molecular basis of receptor binding and antibody neutralization in Nature online.
of Omicron", which showed the closed and open states of Omicron spikes (S) by cryo-EM analysis, which appear to be more compact than their counterparts of the G614 strain, possibly indicating conformational masking of Omicron immune evasion mechanism
.
This study captures three states of the Omicron S-ACE2 complex, revealing that substitution on the Omicron RBM leads to new salt bridges/hydrogen bonds, more favorable electrostatic surface properties, and an overall enhanced S-ACE2 interaction, consistent with the observed Omicron S has higher ACE2 affinity relative to G614
.
Furthermore, this study determined the structure of Omicron S complexed with the Fab of S3H3, an antibody capable of cross-neutralizing variants of prime interest including Omicron, elucidating the structural basis for S3H3-mediated broad-spectrum neutralization
.
The findings shed new light on receptor engagement and antibody neutralization/evasion of Omicron and may also inform the design of broadly effective SARS-CoV-2 vaccines
.
On February 8, 2022, Science published a collaboration between the team of Xu Huaqiang/Yin Wanchao from Shanghai Institute of Materia Medica, Chinese Academy of Sciences, and the team of Jimin Xinxin Deng Sujun, entitled "Structures of the Omicron Spike trimer with ACE2 and an anti-Omicron antibody.
"The latest achievement, the study analyzed the spike protein of the poisonous Omicron mutant strain, and the high-resolution cryo-electron microscope structure that binds to its receptor ACE2 and the broad-spectrum anti-COVID-19 antibody JMB2002, respectively.
The molecular mechanism of rapid spread and immune escape of mutant strains, and revealed a new mechanism of action of the therapeutic antibody JMB2002, providing new ideas for the design and development of broad-spectrum anti-COVID-19 antibodies (click to read)
.
On January 21, 2022, the research team of Zhu Xuan/Chen Fuhe/Yuan Guoyong of the University of Hong Kong and the research team of the Key Laboratory of Tropical Translational Medicine, Hainan Medical College, Ministry of Education, jointly published a paper entitled "Attenuated replication and pathogenicity of SARS-CoV in Nature online.
-2 B.
1.
1.
529 Omicron" research paper showing that replication of Omicron variants is significantly attenuated in Calu3 and Caco2 cells
.
Further mechanistic studies revealed that the Omicron variant was inefficient in the use of transmembrane serine protease 2 (TMPRSS2) compared to the WT and previous variants, which could explain its reduced replication in Calu3 and Caco2 cells
.
Omicron replication in the upper and lower airways of infected K18-hACE2 mice was significantly attenuated compared to WT and Delta variants, which resulted in a significant improvement in their lung pathology
.
Omicron variant infection resulted in minimal weight loss and mortality compared to SARS-CoV-2 WT, Alpha, Beta and Delta variants
.
Overall, this study shows that the Omicron variant has attenuated viral replication and pathogenicity in mice compared to WT and previous variants (click to read)
.
On January 5, 2022, Wang Peiyi of Southern University of Science and Technology, Gao Fu and Qi Jianxun of the Institute of Microbiology, Chinese Academy of Sciences published a joint communication in Cell Online entitled "Receptor binding and complex structures of human ACE2 to spike RBD from Omicron and Delta SARS-CoV-2 ” research paper, which explored the binding properties between the human receptor ACE2 (hACE2) and VOC RBD, and solved the crystal and cryo-EM structures of the Omicron RBD-hACE2 complex and the Delta RBD-hACE2 complex
.
The study found that, unlike Alpha, Beta, and Gamma, Omicron RBD had similar binding affinity to hACE2 compared to prototypic RBD, likely due to the compensation of multiple mutations for immune escape and transmissibility
.
The complex structures of Omicron-hACE2 and Delta-hACE2 reveal the structural basis for how RBD-specific mutations bind to hACE2 (click to read)
.
Receptor binding is a critical step in viral invasion
.
Similar to SARS CoV, SARS-CoV-2 uses its spike (S) protein to recognize the host receptor ACE2
.
The C-terminal domain (CTD) of the S protein, also known as the receptor binding domain (RBD), is responsible for ACE2 recognition and is an important determinant of host range
.
In addition, the S protein is the primary target of neutralizing antibodies
.
Mutations in the S protein, especially RBD, may lead to immune escape and disrupt the efficacy of current therapies and vaccines
.
Due to continued global spread, SARS-CoV-2 continues to evolve into new variants
.
Variants with evidence of increased infectivity, severe disease, reduced antibody neutralization in recovered individuals or vaccines, and a higher risk of evading detection were classified as variants of interest (VOC)
.
Currently, the World Health Organization (WHO) has announced five VOCs, namely Alpha, Beta, Gamma, Delta and the recently identified Omicron
.
The study reported that VOCs, especially the Beta variant, experienced immune escape when treated with most clinically available monoclonal antibodies
.
There have also been reports of compromised protective efficacy of currently licensed vaccines against previous VOCs, although the reduction in efficacy has been quite mild
.
Delta VOC was shown to have a higher transmission rate, which could be explained by its higher replication rate and S-mediated entry
.
Article pattern diagram (image from Cell) Unlike other VOCs that appear when innate immunity prevails, Omicron appears in the context of widespread vaccination against SARS-CoV-2
.
Genome sequencing revealed that Omicron carries an unusually high number of mutations, especially in the S protein (23 amino acid substitutions) and its RBD (15 amino acid substitutions)
.
Putative analyses suggest that some mutations are associated with enhanced viral transmission, infectivity, and immune evasion
.
Recent studies have shown that Omicron can escape abundantly from neutralizing antibodies and sera from convalescent patients or from people vaccinated with Pfizer's vaccine BNT162b2
.
Unraveling the molecular mechanisms of VOC receptor recognition is critical to understanding the impact of Omicron on infection, transmission, and immune escape
.
In this study, several VOCs were examined, including Alpha, Beta, Gamma, Delta, and Omicron, and it was demonstrated that the Omicron variant RBD binds hACE2 with comparable affinity to the prototype
.
The study then determined the crystal and cryo-EM structures of Omicron RBD in complex with hACE2 and identified the role of key residues in receptor recognition
.
Furthermore, this study solved the crystal structure of the Delta RBD-hACE2 complex
.
The findings provide important molecular information about Omicron and Delta VOC and may guide the development of novel preventive/therapeutic approaches targeting major Omicron variants
.
Reference message: https://#relatedArticles
