COVID-19 has swept the world for almost three years, while the causing agent SARS-CoV-2 virus has been continuously evolving. In this issue, Virologica Sinica presents a special topic on COVID-19 and includes a collection of original articles on the characteristics of novel variants and their diagnostics and treatment, immune protection and escape of vaccines and therapeutic antibodies, basic virology and viral decontamination strategies, and et al. We hope these researches would contribute to contain the spread of the coronavirus pandemic and help care for those affected. The cover shows the virus particles of SARS-CoV-2 Omicron variant, with mutations in the spike protein highlighted in yellow.
How do we measure vaccine efficacy? The strictest but also easiest parameter to determine vaccine efficacy is its ability to block infection. Indeed, if a vaccine is able to block infection, this necessarily follows that it will also prevent both disease development and viral transmission. As a consequence, antibodies, specifically neutralising antibodies, have been used as the “gold standard” correlate of protection to measure SARS-CoV-2 vaccine efficacy, given their ability to block infection. Since SARS-CoV-2 infects cells by the binding of its spike protein to the host ACE-2 receptor, a vaccine that is able to induce a large quantity of antibodies able to block the interaction between the ACE-2 receptor and spike protein should theoretically be highly efficacious. Given this “antibody-centric” method of evaluating of a vaccine, it is clear why spike mRNA vaccines have to date been regarded the most effective COVID-19 vaccine in the market.
The recently discovered SARS-CoV-2 variant Omicron (B.1.1.529) has rapidly become a global public health issue. The substantial mutations in the spike protein in this new variant have raised concerns about its ability to escape from pre-existing immunity established by natural infection or vaccination. In this review, we give a summary of current knowledge concerning the antibody evasion properties of Omicron and its subvariants (BA.2, BA.2.12.1, BA.4/5, and BA.2.75) from therapeutic monoclonal antibodies and the sera of SARS-CoV-2 vaccine recipients or convalescent patients. We also summarize whether vaccine-induced cellular immunity (memory B cell and T cell response) can recognize Omicron specifically. In brief, the Omicron variants demonstrated remarkable antibody evasion, with even more striking antibody escape seen in the Omicron BA.4 and BA.5 sub-lineages. Luckily, the third booster vaccine dose significantly increased the neutralizing antibodies titers, and the vaccine-induced cellular response remains conserved and provides second-line defense against the Omicron.
SARS-CoV-2 variants of concern (VOCs)突变株在世界各地的仍在流行。但是,灭活疫苗血清和康复者血清对B.1.1.7(Alpha)、B.1.351(Beta)、P.1(Gamma)、B.1.617.2(Delta)和B.1.1.529(Omicron)等所有VOCs的中和水平还缺乏比较分析。因此,我们利用慢病毒构建了五种VOCs的假病毒,并分析了它们的感染性和对不同时间康复者和灭活病毒疫苗血清中和抗性。结果表明,五种VOC假病毒的感染率均高于野生型(WT),其中B.1.617.2和B.1.1.529变异假病毒的感染率分别高于野生型和其他VOC毒株。10名接种过两剂疫苗后1、3和5个月的人的血清,和10名出院后14和200天康复者血清,分别对所有毒株保持中和活性,但与WT相比,随着时间的推移,血清对五种VOC突变株假病毒的中和活性显著下降。值得注意的是,100%(30/30)接种者血清样本对B.1.1.529的中和活性降低了2.5倍以上。90%(18/20)的恢复期血清与B.1.1.529的中和作用降低了2.5倍以上。这些发现表明,随着时间的推移,接种疫苗和康复的个体对VOCs的保护作用减弱,这表明有必要进接种加强针,并开发能够引发广泛中和抗体的新疫苗。
Due to our negligence, the original version of this article, published online on 17 June 2022, contained a mistake in Table 2. The positive animal number for unclassified goats/sheep in the fourth line should be 44. The seropositive rate "3.1%" is correct thus remains unchanged. The corrected Table 2 is given below. We apologize for our oversight when preparing the table and state that this does not change the scientific conclusions of the article in any way.