The 2014–15 influenza season saw the emergence of an H3N2 antigenic drift variant that formed the 3C.2a HA clade. Whole viral genomes were sequenced from nasopharyngeal swabs of ninety-four patients with confirmed influenza A virus infection and primary human nasal epithelial cell cultures used to efficiently isolate H3N2 viruses. The isolates were classified by HA clade and the presence of a new set of co-selected mutations in NA (a glycosylation site, NAg+) and PB1-F2 (H75P). The NA and PB1-F2 mutations were present in a subset of clade 3C.2a viruses (NAg+F2P), which dominated during the subsequent influenza seasons. In human nasal epithelial cell cultures, a virus with the novel NAg+F2P genotype replicated less well compared with a virus with the parental genotype. Retrospective analyses of clinical data showed that NAg+F2P genotype viruses were associated with increased cough and shortness of breath in infected patients.

中文翻译：

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2014-15 流感季节 H3N2 NA 和 PB1-F2 基因变异的鉴定及其与疾病症状的关联

2014-15 流感季节出现了形成 3C.2a HA 进化枝的 H3N2 抗原漂移变体。从 94 名确诊的甲型流感病毒感染患者的鼻咽拭子和用于有效分离 H3N2 病毒的原代人鼻上皮细胞培养物中对全病毒基因组进行了测序。分离物通过 HA 进化枝和 NA（糖基化位点，NAg+）和 PB1-F2（H75P）中存在的一组新的共同选择突变进行分类。NA 和 PB1-F2 突变存在于进化枝 3C.2a 病毒 (NAg+F2P) 的一个子集中，在随后的流感季节占主导地位。在人鼻上皮细胞培养物中，与具有亲本基因型的病毒相比，具有新型 NAg+F2P 基因型的病毒复制得较差。