交叉反应性T细胞免疫抗H10N8禽流感病毒感染的实验研究

The constant evolution of influenza-virus surface proteins by point mutations or genetic reassortments enables evasion from strain-specific protective humoral immunity. Populations are susceptible to reassortments due to lack of protective antibodies, and the fatality rate is often high. Previous studies have shown that CD4+ and CD8+ T cells induced by seasonal influenza can crossrecognize internal proteins of the newly emerged 2009 pandemic H1N1 virus, and are associated with a decreased severity of symptomatic illness. Such crossreactive T cells, which recognize epitopes that are conserved across viral subtypes, might potentially mediate this heterosubtypic immunity and confer protection against symptomatic illness in individuals lacking pre-existing humoral immunity to the pandemic virus. We found there were no avian influenza A (H10N8) patients among those who were engaged in breeding and selling poultry, despite much higher frequency of exposure to contact with live poultry than general populations. We hypotheses that pre-existing crossreactive T cells induced by frequently contact with live poultry infected with heterosubtypic avian influenza virus may play a role in protection of H10N8 infection. To test this hypothesis, a seroepidemiological investigation will be used to demonstrate the situations of infection among live poultry workers and general populations. Peripheral blood monouclear cells (PBMCs) response to specific H10, HA/NA broad spectrum antibodies against H10N8 virus, and specific T cells response to H10 and N8 peptides, and crossreactive T cells response to highly conserved peptides of internal proteins, all of which will be conducted to clarify the frequency and intensity of pre-existing crossreactive T cells, and the relationship between crossreactive T cells and specific response to specific and broad spectrum antibodies among live poultry workers and general populations. Thus we can provide scientific evidence for risk assessment of transmission and development of control measures.

流感病毒通过点突变或基因重组逃脱特异性体液免疫保护。季节性流感诱导的CD4+和CD8+T细胞可交叉识别pdmH1N1内部蛋白降低疾病严重程度,这种识别流感病毒高度保守表位的交叉反应T细胞为缺乏体液免疫的个体提供了保护。活禽养殖和销售的从业人员暴露于新型H10N8病毒的频率和剂量远高于普通人群但不发病。是否因频繁接触携带其它病毒的活禽产生了交叉反应的T细胞使其免于发病？本研究拟通过人群血清流行病学调查，明确活禽职业人群与普通一般人群感染状况；检测两组人群外周血单核细胞对H10N8特异性H10、HA/NA广谱性抗体应答；病毒H10、N8多肽特异性T细胞应答；病毒内部保守蛋白多肽交叉反应性T细胞应答。从而明确交叉反应性T细胞在高危职业人群及一般人群中的频率与强度；交叉反应的CD4+ T与特异性、广谱抗体反应强度的相关性。为尽早评估H10N8禽流感病毒传播风险提供科学参考。

项目掌握了南昌地区活禽相关职业暴露人群和社区人群的禽流感病毒抗体水平。研究结果显示活禽职业人群记忆性T细胞对流感病毒肽库刺激应答率达66%，对H9亚型禽流感病毒抗原肽应答率高达91%，T细胞对禽流感病毒NP/M1应答频率/强度随着活禽职业暴露时间增加而增强，T细胞对禽流感病毒NP/M1抗原应答的血清标本中对H1、H3和H9的交叉反应率（21%）高于对季节性流感病毒的交叉反应率（12%）。另外，依托本项目还阐明了新型H10N8禽流感病毒的基因起源、进化和致病机制，明确了活禽市场内H10N8、H9N2等主要禽流感病毒亚型的分布和气溶胶传播的病毒学依据，同时项目还发现了一种全新重组的H9N6禽流感病毒（JX-H9N6），并研究了其基因起源和分子特征。项目实施期间在国际国内学术期刊发表标注该项目的学术论文7篇，其中SCI论文6篇。