Department of Microbiology and Immunology, University of Louisville, Kentucky, United States of America.
PLoS One. 2013;8(2):e56602. doi: 10.1371/journal.pone.0056602. Epub 2013 Feb 18.
To capture the possible genotypic and phenotypic differences of the 2009 influenza A virus H1N1 pandemic (H1N1pdm) strains circulating in adult hospitalized patients, we isolated and sequenced nine H1N1pdm viruses from patients hospitalized during 2009-2010 with severe influenza pneumonia in Kentucky. Each viral isolate was characterized in mice along with two additional H1N1 pandemic strains and one seasonal strain to assess replication and virulence. All isolates showed similar levels of replication in nasal turbinates and lung, but varied in their ability to cause morbidity. Further differences were identified in cytokine and chemokine responses. IL-6 and KC were expressed early in mice infected with strains associated with higher virulence. Strains that showed lower pathogenicity in mice had greater IFNγ, MIG, and IL-10 responses. A principal component analysis (PCA) of the cytokine and chemokine profiles revealed 4 immune response phenotypes that correlated with the severity of disease. A/KY/180/10, which showed the greatest virulence with a rapid onset of disease progression, was compared in additional studies with A/KY/136/09, which showed low virulence in mice. Analyses comparing a low (KY/136) versus a high (KY/180) virulent isolate showed a significant difference in the kinetics of infection within the lower respiratory tract and immune responses. Notably by 4 DPI, virus titers within the lung, bronchoalveolar lavage fluid (BALf), and cells within the BAL (BALc) revealed that the KY/136 replicated in BALc, while KY/180 replication persisted in lungs and BALc. In summary, our studies suggest four phenotypic groups based on immune responses that result in different virulence outcomes in H1N1pdm isolates with a high degree of genetic similarity. In vitro studies with two of these isolates suggested that the more virulent isolate, KY/180, replicates productively in macrophages and this may be a key determinant in tipping the response toward a more severe disease progression.
为了捕捉 2009 年甲型 H1N1 流感大流行（H1N1pdm）病毒株在成年住院患者中可能存在的基因型和表型差异，我们从肯塔基州 2009-2010 年因严重流感肺炎住院的患者中分离并测序了 9 株 H1N1pdm 病毒。我们在小鼠中对每个病毒分离株进行了特征描述，同时还对另外两株 H1N1 大流行株和一株季节性株进行了特征描述，以评估其复制和毒力。所有分离株在鼻甲骨和肺中的复制水平相似，但在引起发病的能力上有所不同。在细胞因子和趋化因子反应方面也存在进一步的差异。在感染与高毒力相关的菌株的小鼠中，IL-6 和 KC 早期表达。在小鼠中表现出较低致病性的菌株具有更大的 IFNγ、MIG 和 IL-10 反应。细胞因子和趋化因子谱的主成分分析（PCA）显示了 4 种免疫反应表型，这些表型与疾病的严重程度相关。具有快速发病进展的最强毒力的 A/KY/180/10 与在小鼠中具有低毒力的 A/KY/136/09 进行了比较研究。在比较低毒力（KY/136）与高毒力（KY/180）分离株的研究中，在下呼吸道内感染的动力学和免疫反应方面存在显著差异。值得注意的是，在 4dpi 时，肺内、支气管肺泡灌洗液（BALf）和 BAL 内细胞（BALc）中的病毒滴度表明，KY/136 在 BALc 中复制，而 KY/180 的复制则在肺和 BALc 中持续存在。总之，我们的研究基于免疫反应提出了四个表型组，这些表型组导致具有高度遗传相似性的 H1N1pdm 分离株产生不同的毒力结果。对其中两个分离株的体外研究表明，更具毒力的分离株 KY/180 在巨噬细胞中有效复制，这可能是导致反应向更严重疾病进展的关键决定因素。
