Objective To establish a simple and reliable experimental rodent model sensitive to coxsackievirus A16 ( CVA16) .Methods Mongolian gerbils with different age were selected and inoculated intraperitoneally with live CVA16, and the gerbils were observed daily until 14 days postinoculation to screen for the most optimal ages sensitive to the virus.The dose-dependent symptoms were evaluated and the 50% lethal dose (LD50) was determined.The virus titers were measured in blood and various tissues of CVA 16-infected Mongolian gerbils 3 days post-infecton.Finally, the gerbils were immunized twice with inactivated CVA 16 vaccine at day 1 and day 11, respectively, followed by challenge with the virus with a dose of LD50 at day 14.The gerbils were then observed for another 2 weeks to record their body weight , symptom and mortality rate .Their blood samples were collected from the eyes , and CVA16-specific neutralizing antibodytiters and total antibody titers was checked by microneutralization test and ELISA , respectively .Results Various clinical symptoms, such as inactivity, hind limb weakness, paralysis and even death occurred in gerbils following CAV 16 infection. 7-day-old and 14-day-old gerbils are susceptible to CVA 16 infection whereas 28-day-old gerbils are resistant .The most sensitive and appropriate age is 14-day-old.The 50%lethal dose was determined to be 1×104.5 CCID50.High titers of the virus were confirmed in blood and various tissues of Mongolian gerbils contracted CAV 163 days post-infecton.The survival rate is 87.5%for 14-day-old gerbils preimmunized with two doses of inactivated CVA 16 vaccine and challenged with the virus.The geometric mean titers ( GMTs) of neutralizing antibody was 28.14, and the seroprevalence was 87.5%.Conclusions Mongolian gerbils is sensitive to CVA16 and the virus reproduces actively in Vivo.Thus, it can be used as a reliable small animal model for studies of CVA 16 pathogenesis , vaccine development and drug evaluation .%目的 建立简便和可靠的对柯萨奇病毒A16型(coxsackievirus A16,CVA16)敏感的小型啮齿类实验动物模型.方法 选取不同日龄长爪沙鼠,腹腔接种CVA16后连续观察14 d,筛选出对病毒敏感的最适接种日龄段;然后比较接种剂量与效应关系,测定其50%致死剂量(LD50);并测定感染3 d后其血液和主要组织器官中CVA16病毒滴度;最后用CVA16灭活疫苗在1日龄和11日龄免疫2针沙鼠后,在14日龄时用LD50剂量病毒攻毒,观察并记录沙鼠体重、症状及死亡率,2周后眼球采血,应用微量中和试验和ELISA分别检测中和抗体效价和总抗体水平.结果 长爪沙鼠感染CVA16后出现活动减少、后肢无力、麻痹瘫痪、死亡等临床症状,不同日龄沙鼠对CVA16感染的易感能力和感染后发病程度不同,7日龄和14日龄沙鼠易感,28日龄沙鼠不易感染,最敏感和最合适接种日龄为14日龄,其LD50为1×104.5 CCID50,感染3 d后其血液和主要组织器官中均可检测到高滴度的CVA16病毒,免疫两针灭活疫苗的14日龄沙鼠用LD50剂量攻毒,存活率87.5%,疫苗免疫诱导沙鼠产生的CVA16中和抗体几何平均值(GMT)为28.14,抗体阳性率为87.5%.结论 长爪沙鼠对CVA16敏感并且病毒能在其体内进行有效的复制和繁殖,可作为CVA16致病机制研究、疫苗研发及药物评价的可靠小动物模型.
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