Brault Aaron C, Powers Ann M, Weaver Scott C
Center for Tropical Diseases and Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA.
J Virol. 2002 Jun;76(12):6387-92. doi: 10.1128/jvi.76.12.6387-6392.2002.
Epizootic subtype IAB and IC Venezuelan equine encephalitis viruses (VEEV) readily infect the epizootic mosquito vector Aedes taeniorhynchus. The inability of enzootic subtype IE viruses to infect this mosquito species provides a model system for the identification of natural viral determinants of vector infectivity. To map mosquito infection determinants, reciprocal chimeric viruses generated from epizootic subtype IAB and enzootic IE VEEV were tested for mosquito infectivity. Chimeras containing the IAB epizootic structural gene region and, more specifically, the IAB PE2 envelope glycoprotein E2 precursor gene demonstrated an efficient infection phenotype. Introduction of the PE2 gene from an enzootic subtype ID virus into an epizootic IAB or IC genetic backbone resulted in lower infection rates than those of the epizootic parent. The finding that the E2 envelope glycoprotein, the site of epitopes that define the enzootic and epizootic subtypes, also encodes mosquito infection determinants suggests that selection for efficient infection of epizootic mosquito vectors may mediate VEE emergence.
流行IAB和IC亚型委内瑞拉马脑炎病毒（VEEV）很容易感染流行的蚊媒——带喙伊蚊。地方流行性IE亚型病毒无法感染这种蚊种，这为鉴定载体感染性的天然病毒决定因素提供了一个模型系统。为了绘制蚊子感染决定因素图谱，对由流行IAB和地方流行性IE亚型VEEV产生的相互嵌合病毒进行了蚊子感染性测试。含有IAB流行结构基因区域，更具体地说是IAB PE2包膜糖蛋白E2前体基因的嵌合体表现出高效感染表型。将来自地方流行性ID亚型病毒的PE2基因导入流行IAB或IC基因骨架中，导致感染率低于流行亲本。E2包膜糖蛋白是定义地方流行性和流行性亚型表位的位点，它也编码蚊子感染决定因素，这一发现表明，选择高效感染流行蚊媒可能介导了VEE的出现。
