【作者】 张延光；

【导师】 刘月焕；

【作者基本信息】 中国农业科学院 ， 基础兽医学， 2009， 硕士

【摘要】 2007年12月,北京某马场共有23匹马,一周内有21匹相继发病,根据流行病学调查和临床症状初步疑似马流感。采集病马的鼻汁,经处理后接种SPF鸡胚,分离到一株马流感病毒,经经HI和基因序列分析试验鉴定为H3N8亚型马流感病毒,毒株命名为A/Equine/Huabei/2/2007(H3N8),简称EHB07,鸡胚半数感染量为106.5EID50/0.1ml。确诊本次疫情由H3N8亚型马流感病毒感染引起。EHB07的HA基因与鸭源毒株A/Duck/Ukraine/1963(H3N8)、A/Nanchang/1681/1992(H3N8)和中国吉林分离株A/Equine/Jilin/1/1989(H3N8)的同源性较低(本毒株为迄今为止唯一的一株从马体分离到的禽源流感毒株)(Guo Y,1992),分别为76.85,77.1%和77.8%,与其它马源毒株的同源性较高,为90.4%-99.1%,其中与2005年意大利巴里分离毒株A/Equine/Bari/2005(H3N8)的同源性最高,达99.1%。与日本茨城分离毒株已发表的部分序列比较发现,二者的同源性为97.63%。EHB07的NA基因和2007年日本分离株A/Equine/Ibaraki/1/07(H3N8)处于同一分支内,亲缘关系最近,同源率97.3%；与鸭源毒株和中国吉林分离的马源毒株差异较大,同源性差,同源率为74.8%-77.2%,其中与吉林株的核苷酸同源率为74.9%。除此以外,本实验毒株与世界上分离的其它马源毒株的同源率为90.0%-98.7%,与2002年美国肯塔基州的分离毒株同源性最高,达98.7%。因此,也说明本实验分析的毒株起源于马,而非禽类。与1992年本地发生的马流感疫情相比,本次疫情具有流行范围小、传播速度慢、病情缓和、容易治疗、恢复迅速的特点。2004年-2006年美国连续发生犬流感疫情,而且初步研究确定犬流感是由H3N8亚型马流感病毒感染引起,受到全世界的关注。为了确定A/Equine/Huabei/2/2007(H3N8, F4)毒株对犬的易感性,我们选择14只宠物犬进行了攻毒试验。以105.5EID50/只(条)的剂量经滴鼻点眼和静脉注射的途径进行攻毒,攻毒后定期检查犬的临床症状表现、体温、血常规、血清生化并采集鼻咽拭子,并按照试验设计于攻毒后6天、14天分别剖杀试验犬,采集脏器病料进行病毒分离和病理组织学观察。结果所有攻毒犬无任何临床感染的症状,体温、血细胞数量、生化指标均无任何异常,病例组织学观察未见明显病变,病毒分离除了有一条金色寻回猎犬的鼻咽拭子分离到病毒外其余均为阴性,抗体检测仅有一条金色寻回猎犬犬在14天的血清中检测到很低的抗体(1：20)。初步试验结果表明本次试验用犬对F4代A/Equine/Huabei/2/2007(H3N8)不易感。更多还原

【Abstract】 Due to the invasion of foreign epidemic, suspected equine influenza outbreak occurred in a horse farm of Beijing in December,2007. Among the total 23 horses of the farm,21 were attacked by disease constantly within a week which was identified as equine influenza preliminarily according to epidemiological investigation and clinical symptoms. Inoculated the collected horse swab after being treated with SPF chicken embryos, an equine influenza virus strain was isolated and identified as Subtype H3N8 equine influenza virus with half the infection amount of chicken embryos of 106.5EID50/0.1ml. The strain was named A/Equine/Huabei/2/2007 (H3N8) and referred to as EHB07. Initial diagnosis showed that this epidemic was caused by the infection of Subtype H3N8 equine influenza virus. Compared with the horse flu outbreak occurred locally in 1992, this epidemic was characterized by small-area and slow spread, eased symptoms, easy treatment, and quick recovery.During 2004 and 2006, canine influenza occurred consecutively in the United States; preliminary study confirmed that it was caused by the infection of Subtype H3N8 equine influenza virus, which caused worldwide attention. To determine the susceptibility of A/Equine/Huabei/2/2007 (H3N8) strain on dogs,14 pet dogs were selected and tapped Challenge Test. The challenge routes were intranasal-and-eyed infection and intravenous injection with the amount of attack agents 105.5EID50. After the challenge, checked regularly the dogs’clinical symptoms, temperature, blood, serum biochemical and collected nasopharyngeal swabs; 6 to 14days later, killed and dissected all the dogs, collected viscera materials for virus isolation and histological observation. The result was that all dogs inoculated showed no clinical symptom of infection, no abnormal situation in body temperature, blood cells and biochemical parameters, and no obvious lesions through histological observation. Except that virus was isolated from the nasopharyngeal swabs of a Golden Retriever among the dogs, all viruses isolated were negative. In antibody test, only a Golden Retriever was found of low antibodies in the 14-day serum (1:20). Based on the results above, it could be affirmed preliminarily that this experimental strain had no obvious infectious on dogs.更多还原