浙江大学顶级杂志：H7N9病毒在禽和人中的相似性

来自浙江大学医学院附属第一医院，传染病诊断和治疗国家重点实验室的研究人员完成了人感染H7N9禽流感病毒的临床分析和特征表述，这是首次公布的感染患者和受感染禽类的全序列基因组，其中明确证明了活禽市场的鸡是人感染H7N9禽流感病毒的源头之一。

　　

生物通报道：来自浙江大学医学院附属第一医院，传染病诊断和治疗国家重点实验室的研究人员发表了题为“Human infections with the emerging avian influenza A H7N9 virus from wet market poultry: clinical analysis and characterisation of viral genome”的文章，完成了人感染H7N9禽流感病毒的临床分析和特征表述，这是首次公布的感染患者和受感染禽类的全序列基因组，其中明确证明了活禽市场的鸡是人感染H7N9禽流感病毒的源头之一。

这一研究成果公布在顶级医学期刊Lancet杂志上，并作为头条进行宣传。文章的通讯作者是浙江医科大学医学系李兰娟院士，从事传染病学医疗、教学和研究工作30余年，并取得显著成就，曾创建独特有效的人工肝支持系统治疗重型肝炎（ALSS）获重大突破。

目前据最新消息，全国确诊人数增加至119例（含台湾1例），昨天（4月26日）一天之内增加6例感染H7N9禽流感确诊病例，其中，福建确诊首例，江苏新增3例，浙江、江西各新增1例。

而农业部也表示，截至4月26日，全国各省和国家禽流感参考实验室共发现46份H7N9禽流感病毒阳性，各地没有从家禽养殖场分离到H7N9禽流感病毒，也未发现猪感染该病毒，已经发现的46份H7N9禽流感病毒阳性样本来自活禽经营市场、野鸽及信鸽养殖户。

在这篇Lancet文章中，李兰娟研究组在3月7日至4月8日之间收集了出现新发呼吸道症状，不明原因的放射渗透，实验室确诊H7N9病毒感染的患者，采集喉咙和痰样品，利用RT-PCR方法检测M，H7和N9基因，并在Madin-Darby狗的肾脏细胞中进行培养。同时研究人员也检测了双重感染或重叠感染，观察六种细胞因子和趋化因子的血清浓度。

此外这一组研究人员还完成了86只活禽市场中鸡、鸭、鹌鹑和鸽子的H7N9病毒的采样和分析，并进行了鸡胚接种分析。他们通过RT-PCR测序确定了亚型菌株，并且还通过RNA提取，DNA合成，及PCR测序完成了一个病患和受感染鸡的全序列分析。

从中研究人员指出，这四名患者（平均年龄56岁），在发病前3-8天均与家禽有过接触，之后出现了发热症状，并快速发展成肺炎，抗生素治疗均没有效果。患者出现了白细胞及淋巴细胞减少，肝或肾功能出现损伤，血清细胞因子或趋化因子浓度大幅增加，伴随疾病出现了弥散性血管内凝血。其中两名患者死亡。

从这些病例来看，痰标本比咽拭子样本更易检测出H7N9病毒测试阳性。研究人员从患者体内分离得到的病毒，与从浙江流行病学相关市场中鸡中分离的病毒相似。但是N9与之前韩国发现的野生鸟类H7N9病毒更为接近。

研究人员表示，人类病毒H7（与α-2 ,6-唾液酸受体的亲和力增加有关）中的Gln226Leu和Gly186Val出现变异，PB2 Asp701Asn（与哺乳动物适应性有关）也出现了变异。M2病毒中Ser31Asn突变与金刚烷抗性有关。

据报道，研究人员认为如果PB2基因的627和701氨基酸位点同时发生变异，将会导致有效的人传人.

这项研究首次证明了活禽市场的鸡是人感染H7N9禽流感病毒的源头，这意味着在活禽市场以及这些禽类中控制病毒是重中之重。当然这也并不说所有的人感染H7N9病例都源自鸡或其他禽类，禽类只是其中之一。

（生物通：张迪）

原文摘要：

Human infections with the emerging avian influenza A H7N9 virus from wet market poultry: clinical analysis and characterisation of viral genome

Background
Human infection with avian influenza A H7N9 virus emerged in eastern China in February, 2013, and has been associated with exposure to poultry. We report the clinical and microbiological features of patients infected with influenza A H7N9 virus and compare genomic features of the human virus with those of the virus in market poultry in Zhejiang, China.
Methods
Between March 7 and April 8, 2013, we included hospital inpatients if they had new-onset respiratory symptoms, unexplained radiographic infiltrate, and laboratory-confirmed H7N9 virus infection. We recorded histories and results of haematological, biochemical, radiological, and microbiological investigations. We took throat and sputum samples, used RT-PCR to detect M, H7, and N9 genes, and cultured samples in Madin-Darby canine kidney cells. We tested for co-infections and monitored serum concentrations of six cytokines and chemokines. We collected cloacal swabs from 86 birds from epidemiologically linked wet markets and inoculated embryonated chicken eggs with the samples. We identified and subtyped isolates by RT-PCR sequencing. RNA extraction, complementary DNA synthesis, and PCR sequencing were done for one human and one chicken isolate. We characterised and phylogenetically analysed the eight gene segments of the viruses in the patient's and the chicken's isolates, and constructed phylogenetic trees of H, N, PB2, and NS genes.
Findings
We identified four patients (mean age 56 years), all of whom had contact with poultry 3—8 days before disease onset. They presented with fever and rapidly progressive pneumonia that did not respond to antibiotics. Patients were leucopenic and lymphopenic, and had impaired liver or renal function, substantially increased serum cytokine or chemokine concentrations, and disseminated intravascular coagulation with disease progression. Two patients died. Sputum specimens were more likely to test positive for the H7N9 virus than were samples from throat swabs. The viral isolate from the patient was closely similar to that from an epidemiologically linked market chicken. All viral gene segments were of avian origin. The H7 of the isolated viruses was closest to that of the H7N3 virus from domestic ducks in Zhejiang, whereas the N9 was closest to that of the wild bird H7N9 virus in South Korea. We noted Gln226Leu and Gly186Val substitutions in human virus H7 (associated with increased affinity for α-2,6-linked sialic acid receptors) and the PB2 Asp701Asn mutation (associated with mammalian adaptation). Ser31Asn mutation, which is associated with adamantane resistance, was noted in viral M2.
Interpretation
Cross species poultry-to-person transmission of this new reassortant H7N9 virus is associated with severe pneumonia and multiorgan dysfunction in human beings. Monitoring of the viral evolution and further study of disease pathogenesis will improve disease management, epidemic control, and pandemic preparedness.

作者简介：

李兰娟，传染病学专家。1947年9月出生于浙江绍兴，1972年9月加入中国共产党。中973年毕业于浙江医科大学医学系，教授、主任医师、博士生导师。现任浙江省卫生厅厅长、卫生部传染病重点实验室主任、中华医学会副会长。中华医学会感染病学分会副主任委员、全国人工肝培训基地主任。2005年当选为中国工程院院士。