Scherer W F, Anderson K, Pancake B A, Dickerman R W, Ordonez J V
Am J Epidemiol. 1976 Jun;103(6):576-88. doi: 10.1093/oxfordjournals.aje.a112262.
Seventy-four strains of Venezuelan encephalitis (VE) virus recovered from sentinel hamsters or mosquitoes at enzootic habitats in Guatemala in the two years following the 1969 epidemic-equine epizootic were examined for ability to produce small plaques in Vero African green monkey kidney cell cultures, like isolates obtained during the epizootic. (a) One strain recovered from a sentinel hamster in late October 1969 at an enzootic habitat near the epicenter of the hemagglutination-inhibition (HI) and equine-virulence properties like epizootic virus; this strain retained its small plaque characteristic after inoculation and recovery from bloods of three horses. (b) None of the other 73 strains produced uniformly small plaques, but 31 formed a few small plaques among large ones. Virions from small plaques of five strains were cloned twice in Vero cell cultures. Four clones produced uniformly small plaques after one more passage in Vero cells; three had hemagglutination-pH properties compatible with epizootic virus or intermediate between epizootic and enzootic virus, but HI tests with these three hemagglutinins or with antibody to the fourth cloned strain showed them to be like Central American enzootic virus. One of three cloned strains tested in horses produced encephalitis and death in one of four horses; another strain produced encephalitis with recovery in one of two horses. (c) Thus these small Vero plaque clones resembled Central American enzootic strains of VE virus in HI and equine-virulence tests, and the small Vero plaque characteristic was not a satisfactory marker for consistently isolating equine-virulent, epizootic VE virions. Nevertheless, this technic led to recognition of one epizootic strain isolated at an enzootic habitat in Guatemala at the end of 1969 outbreak. Whether this strain was there before the outbreak or subsequently penetrated the habitat is uncertain. During the next two years, this strain did not become dominant in that enzootic focus.
对1969年马流行性疫病流行后的两年间，从危地马拉动物疫病流行区的哨兵仓鼠或蚊子中分离出的74株委内瑞拉脑炎（VE）病毒，检测其在非洲绿猴肾Vero细胞培养物中产生小噬斑的能力，这些病毒类似于在疫病流行期间分离出的毒株。（a）1969年10月下旬，在血凝抑制（HI）和马毒力特性的震中附近的动物疫病流行区，从一只哨兵仓鼠中分离出一株病毒，其具有与疫病流行病毒相似的特性；该毒株接种到三匹马的血液中并从中恢复后，仍保留其小噬斑特征。（b）其他73株病毒均未产生一致的小噬斑，但有31株在大噬斑中形成了一些小噬斑。从五株病毒的小噬斑中提取的病毒粒子在Vero细胞培养物中进行了两次克隆。四个克隆株在Vero细胞中再传一代后产生了一致的小噬斑；其中三个克隆株的血凝-pH特性与疫病流行病毒相符或介于疫病流行病毒和动物疫病流行病毒之间，但用这三种血凝素或第四株克隆病毒的抗体进行HI试验表明，它们类似于中美洲动物疫病流行病毒。在马身上测试的三株克隆病毒中的一株，使四匹马中的一匹发生脑炎并死亡；另一株使两匹马中的一匹发生脑炎并康复。（c）因此，这些Vero小噬斑克隆株在HI和马毒力试验中类似于中美洲VE病毒的动物疫病流行株，Vero小噬斑特征并不是持续分离出马毒力、疫病流行的VE病毒粒子的令人满意的标志物。尽管如此，这项技术导致在1969年末危地马拉动物疫病流行区分离出一株疫病流行株。该毒株是在疫病爆发前就存在于那里，还是后来进入该地区尚不确定。在接下来的两年里，该毒株在那个动物疫病流行中心并未占主导地位。
