流感病毒的抗原地图揭示了怎样的演化轨迹,为什么流感疫苗几乎每年都要更换毒株?
What evolutionary trajectory does antigenic mapping reveal in influenza, and why must vaccine strains be updated nearly every year?
血凝素上的抗原漂移持续产生逃逸既有抗体的新变异。Smith等用血凝抑制数据构建抗原地图,把毒株按抗体交叉反应的距离排入二维空间,H3N2亚型由此显露出沿一条主轴逐年推进的轨迹;群体免疫不断淘汰旧谱系,携带全新抗原表位的克隆获得传播优势后席卷全球,上一季疫苗随即失效,世界卫生组织因此每年依据这类抗原图更新推荐毒株。
Antigenic drift on hemagglutinin keeps generating variants that escape established antibodies. Building maps from hemagglutination-inhibition data, Smith and colleagues placed strains in two dimensions by antibody cross-reaction distance, revealing H3N2 creeping forward along a single main axis year after year. Herd immunity continuously retires old lineages; once clones bearing novel antigenic epitopes gain a transmission edge they sweep the globe and last season's vaccine loses its grip, which is why WHO refreshes recommended strains annually using such maps.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
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Smith DJ等论文《Mapping the antigenic and genetic evolution of influenza virus》,Science 2004(美国国立卫生研究院与伦敦WHO流感参考研究中心)
Smith DJ et al., 'Mapping the antigenic and genetic evolution of influenza virus', Science, 2004 (US National Institutes of Health and WHO Collaborating Centre for Reference and Research on Influenza, London)
独立核验依据 · Independent verification: 核验依据 1 EUROPEPMC 标识 15218094：Mapping the antigenic and genetic
#病毒演化 #抗原漂移 #流感疫苗
新冠变异株为何反复独立出现N501Y、E484K这类相似突变,深度突变扫描如何解释这种趋同?
Why do SARS-CoV-2 lineages repeatedly and independently converge on mutations such as N501Y and E484K, and how does deep mutational scanning account for this?
因为抗体压力只可能在少数既躲开免疫又不损功能的位点上起效。Starr等对受体结合域做深度突变扫描,测遍数千种氨基酸替换对折叠与ACE2结合的影响,发现绝大多数替换破坏结构或丧失亲和力,可用的逃逸突变屈指可数;流行株遂在全球范围反复独立拾取同款突变:N501Y加强受体结合,E484K、L452R削弱抗体识别,趋同演化由此产生。
Because antibody pressure can only act at the handful of sites where a mutation dodges immunity yet spares function. Deep mutational scanning of the receptor-binding domain by Starr and colleagues measured thousands of amino-acid substitutions for effects on folding and ACE2 binding, showing that most wreck the structure or drop receptor affinity and leaving very few usable escape changes. Circulating lineages worldwide therefore pick up the same mutations independently: N501Y tightens ACE2 engagement while E484K and L452R blunt antibody recognition, and convergence follows.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
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Starr TN等论文《Deep mutational scanning of the SARS-CoV-2 receptor binding domain reveals constraints on folding and ACE2 binding》,Cell 2020(弗雷德·哈金森癌症研究中心Bloom实验室)
Starr TN et al., 'Deep mutational scanning of the SARS-CoV-2 receptor binding domain reveals constraints on folding and ACE2 binding', Cell, 2020 (Bloom lab, Fred Hutchinson Cancer Research Center)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1016/j.cell.2020.08.012：Deep Mutational S
#新冠病毒 #趋同演化 #免疫逃逸
为什么RNA病毒的演化速度能比宿主快上百万倍,这给抗病毒治疗带来哪些麻烦?
Why can RNA viruses evolve up to a million times faster than their hosts, and what trouble does that cause for antiviral therapy?
因为RNA病毒的聚合酶没有校对功能,复制错误几乎不被纠正。Holland等测定水疱性口炎病毒等RNA基因组,推算其演化速率最高可达DNA生物的百万倍;庞大的病毒群体因此构成持续漂移的准种云,耐药株与免疫逃逸株随时待选。单一药物或单表位抗体很快被绕开,临床上须联合用药并瞄准保守靶点,这正是广谱中和抗体与抗病毒鸡尾酒疗法的出发点。
Because their polymerases lack proofreading activity, replication errors go almost wholly uncorrected. Measuring vesicular stomatitis virus and other RNA genomes, Holland and colleagues inferred evolutionary rates up to a million times those of DNA-based organisms. Huge viral populations therefore form a constantly drifting quasispecies cloud stocked with drug-resistant and immune-escape variants ready to emerge. A single drug or a single-epitope antibody is soon bypassed, so therapy leans on combination regimens aimed at conserved targets - the rationale behind broadly neutralizing antibodies and antiviral cocktails.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
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Holland J等论文《Rapid evolution of RNA genomes》,Science 1982(加州大学圣地亚哥分校Holland实验室)
Holland J et al., 'Rapid evolution of RNA genomes', Science, 1982 (Holland lab, University of California, San Diego)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1126/science.7041255：Rapid Evolution of R
#RNA病毒 #准种 #耐药突变