南京市乙型流感病毒老年肺炎患者的临床特点及病毒分子特征

Clinical features and molecular characteristics of influenza B viral pneumonia in elderly patients in Nanjing city

目的了解感染乙型流感病毒的老年肺炎患者的临床特点及所感染病毒的分子特征,为临床诊治和疾病防控提供依据。方法采集2017年12月至2018年3月南京市第一医院住院的老年肺炎患者呼吸道标本,通过荧光定量PCR进行核酸检测,筛选乙型流感病毒感染病例。收集病例临床信息。采用高通量测序技术对乙型流感病毒进行全基因组测序,通过生物信息学方法对HA、NA分子特征进行分析。结果20例患者的中85%患者至少合并1种基础性疾病,70%的患者影像学检查存在双肺病变。患者的病死率为25%。死亡患者与存活者相比,外周血淋巴细胞百分数、血清总胆红素等方面存在显著性差异(P<0.05)。17株乙型流感毒株经序列分析显示,16株属于Yamagata系,1株属于Victoria系。Victoria系毒株的NA基因来源于Yamagata系病毒,发生了基因重配。结论乙型流感病毒老年肺炎患者多合并基础疾病,出现外周血淋巴细胞百分数下降等情况提示患者预后不良,所感染的病毒Yamagata系和Victoria系毒株同时存在,以Yamagata系为主。

Objective To analyze the clinical features of influenza B viral pneumonia among elderly patients and the molecular characteristics of the virus, so as to provide the basis for clinical diagnosis and treatment as well as disease prevention. Methods The respiratory tract samples were collected from hospitalized elderly patients with pneumonia in the Nanjing First Hospital from December, 2017 to March, 2018. Fluroscent quantitative RT-PCR was used in the nucleic acids testing for the screening of influenza B infection cases. The clinical data of the cases were collected. The whole genomes of influenza B virus were sequenced by high-throughput sequencing. Analyses of molecular characteristics for HA and NA were carried out by bioinformatic methods. Results For the 20 patients, 85% of them had at least one underlying disease. Lesions in both lungs were found in 70% of the patients, and the case fatality rate was 25%. The differences in the peripheral blood lymphocyte percentage and total serum bilirubin between death patients and survived patients were statistically significant (P<0.05). The results of sequence analysis for the 17 strains influeuza B showed that 16 strains were belong to Yamagata lineage while 1 strain was in Victoria lineage. The NA gene of the strain in Victoria lineage was originated from the Yamagata lineage, indicating that reassortments may occur. Conclusions Most of the elderly patients with influenza B virus infection were combined with underlying diseases. Decreased peripheral blood lymphocytes percentage indicated poor prognosis. Both Yamagata and Victoria lineages were detected in elderly patients infected by influenza B virus, and stains in Yamagata lineage were predominant.