Investigation for pathogenesis of influenza virus and SARS coronavirus

高致病性禽流感H5 N1病毒（H5 N1-Flu）的空前重现和严重急性呼吸道综合征冠状病毒（SARS-CoV）的爆发对人类构成重大威胁。更好地了解这些高致病性病毒的基本知识和反向遗传学等新技术将有助于我们制定有效的预防和/或治疗策略来控制疾病负荷。我们开发了负链RNA病毒的反向遗传学，并分析了这些病毒复制和致细胞病变的机制。从1岁猪的肺泡组织中制备原代气道上皮细胞，并研究了H5禽流感病毒在这些细胞中的生长动力学。H5 N1病毒在猪气道上皮细胞中显著诱导细胞死亡，尤其是细胞凋亡，尽管这三种病毒在鸡胚成纤维细胞中诱导相似的细胞毒性，表明禽H5 N1流感病毒导致 ...更多信息 哺乳动物呼吸道上皮细胞中由于细胞凋亡的诱导而导致的严重细胞死亡细胞克隆#21是感染性SARS-CoV的长期生产者，尽管刺突（S）蛋白掺入病毒体的速率显著较低。病毒结构蛋白的测序分析显示，S和膜（M）蛋白中分别有4个和1个氨基酸取代。我们证明，使用病毒样颗粒形成系统，S突变参与了较低的S蛋白掺入病毒粒子，虽然M突变破坏糖基化不参与这种表型。进一步的突变实验确定了受体结合结构域内的两个取代Y 442 C和L472 F，这可能是S掺入减少以及S和ACE 2受体之间结合亲和力降低的关键。因此，这两个氨基酸取代可能导致S蛋白的构象变化，导致掺入病毒颗粒的减少。少

The unprecedented re-emergence of highly pathogenic avian influenza H5N1 viruses (H5N1-Flu) and the outbreak of severe acute respiratory syndrome coronavirus (SARS-CoV) pose a significant threat to humans. Better basic knowledge of these highly pathogenic viruses and novel technologies such as reverse genetics will help us to generate effective prophylactic and/or therapeutic strategies to control the disease load. We have developed the reverse genetics of negative strand RNA viruses and were analyzing the mechanisms behind the replication and cytopathicity of these viruses.Primary airway epithelial cells from alveolar tissues were prepared from 1-year-old pigs and the growth kinetics of avian H5 influenza viruses in these cells was investigated. H5N1 virus significantly induced cell death, especially apoptosis, in porcine airway epithelial cells although these three viruses induced similar cell toxicity in chicken embryonic fibroblasts, suggesting that avian H5N1 influenza virus leads … More severe cell death in mammalian airway epithelial cells due to the induction of apoptosis.A cell clone #21 is a long-term producer of the infectious SARS-CoV, although the incorporation rate of spike (S) protein into virions is significantly lower. Sequencing analysis of the viral structural proteins revealed four and one amino acid substitutions in the S and membrane (M) proteins, respectively. We demonstrated, using a viral-like particle formation system, that the S mutations were involved in lower incorporation of the S protein into virions, although the M mutation disrupting the glycosylation was not involved in this phenotype. Further mutational experiments identified two substitutions, Y442C and L472F, within the receptor binding domain that could be critical for the reduced S incorporation, as well as reduced binding affinity between the S and ACE2 receptor. Thus, these two amino acid substitutions might lead to a conformational change in the S protein, resulting in reduced incorporation into viral particles. Less