新疆夏尔希里自然保护区蜱传脑炎疫源地调查

Investigation on the endemic foci of new emerged tick-borne encephalitis in Charles Hilary, Xinjiang

目的调查新疆北部夏尔希里地区蜱传脑炎（TBE）疫源地特征，分离鉴定蜱传脑炎病毒（TBEv）。方法利用间接免疫荧光法对2011年春夏季出现的2例疑似病毒性脑炎患者及当地健康人群检测TBEV特异性IgG抗体。调查当地蜱种群特征；通过蜱研磨液接种实验小鼠与细胞分离培养TBEV；利用RT-PCR扩增检测病毒NS1基因片段，通过序列分析明确新分离毒株的系统进化特征。结果在夏尔希里自然保护区TBE疫源地采集全沟硬蜱和森林革蜱共1760只，全沟硬蜱为优势蜱种（87．5％）。2例疑似病毒性脑炎患者确诊为TBEV感染。当地健康人群中病毒IgG血清阳性率为35．4％（23／65）。BALB／c小鼠接种蜱研磨液后，发病与死亡发生率分别为72．9％（70／96）和55．7％（44／79）。从病死小鼠脑组织中扩增获得TBEV特异性条带。基于病毒NS1基因序列的系统进化分析表明，TBEV新分离株属于远东亚型，与中国东北地区分离株、俄罗斯分离株的同源性分别为99％和98％。结论首次发现新疆夏尔希里自然保护区存在TBE疫源地，病毒流行株属于远东亚型，全沟硬蜱和森林革蜱是病毒传播的重要媒介。

Objective To investigate the recent emerged endemic region of tick-borne encephalitis （TBE） regarding its natural reserves, in Charles Hilary, northern Xinjiang and to isolate and characterize the viral geographic strain. Methods Using indirect fluorescent assay to detect tickborne encephalitis virus （TBEV） specific IgG antibodies from serum of local residents including 2 unconfirmed viral encephalitis patients in 2011 spring-summer. Viruses were isolated from tick samples by inoculating BALB/c mice and BHK-21 cells. For phylogenetic analysis. TBEV NS1 gene fragments were detected by RT-PCR and then subjected to sequence alignment. Results 1760 ticks were captured from the fields to have found that lxodes persuleatus were dominated among the tick population. Two viral encephalitis patients were diagnosed as TBEV infection. In addition, 35.4% （23/ 65） local residents were detected positive for presence of TBEV specific-IgG antibodies in serum. After inoculation, morbidity and mortality of BALB/c mice were 72.9% （70/96） and 55.7% （44/79）, respectively. TBEV specific-fragments were amplified from brain tissue of dead mice and cells culture supernatant. NS1 sequence alignment showed that the viral isolates were clustered into TBEV far- eastern sub-type, phylo-genetically, and were mostly close to the isolates from northeastern China （99%） and Russian strain （98%）. Conclusion In this study, a new endemic loci of TBE was firstly described in Charles Hilary natural reserve, northem Xinjiang. TBEV geographic isolates belonged to TBEV far-eastern subtype while Ixodes persuleatus and Dermacentor silvarum played crucial roles for disease transmition.