Langevin Stanley A, Arroyo Juan, Monath Thomas P, Komar Nicholas
Centers for Disease Control and Prevention, Fort Collins, Colorado 80522, USA.
Am J Trop Med Hyg. 2003 Jul;69(1):78-80.
We evaluated a recombinant virus chimera, ChimeriVax-WN, in which the West Nile virus (WNV) surface protein genes (pre-membrane [prM] and envelope [E]) are substituted into the genome of the 17D vaccine strain yellow fever virus (YF-17D), as a vaccine candidate for protection of birds from WNV disease. Using fish crows (Corvus ossifragus) as a model, we found that none of eight crows that received two high doses of vaccine (approximately 100,000 plaque-forming units [PFU]) developed viremia and only one developed WNV-neutralizing antibodies. When challenged with subcutaneous injection of 2,000 PFU of WNV (NY99 strain), all eight developed viremia levels similar to unvaccinated control birds (n = 4). Two of the vaccinated birds died of the infection, compared with no mortality in the four controls. To further investigate the failure of the vaccine, we inoculated chickens with both the vaccine and YF-17D and found no evidence of replication with either of these viruses. These data indicate that this vaccine candidate failed to protect birds from the morbidity and mortality attributed to WNV infections. However, if used in mammals, this recombinant viral vaccine is unlikely to inadvertently enter a natural transmission cycle with birds as amplifying hosts.
我们评估了一种重组病毒嵌合体ChimeriVax-WN，其中西尼罗河病毒（WNV）的表面蛋白基因（前膜蛋白[prM]和包膜蛋白[E]）被替换到17D疫苗株黄热病病毒（YF-17D）的基因组中，作为一种保护鸟类免受WNV疾病侵害的候选疫苗。以食鱼鸦（Corvus ossifragus）为模型，我们发现接受两剂高剂量疫苗（约100,000个噬斑形成单位[PFU]）的八只食鱼鸦中，没有一只出现病毒血症，只有一只产生了WNV中和抗体。当皮下注射2,000 PFU的WNV（NY99株）进行攻毒时，所有八只食鱼鸦的病毒血症水平与未接种疫苗的对照鸟（n = 4）相似。两只接种疫苗的鸟死于感染，而四只对照鸟无一死亡。为了进一步研究疫苗失效的原因，我们给鸡接种了该疫苗和YF-17D，未发现这两种病毒有复制的迹象。这些数据表明，这种候选疫苗未能保护鸟类免受WNV感染所致的发病和死亡。然而，如果用于哺乳动物，这种重组病毒疫苗不太可能意外地与作为扩增宿主的鸟类进入自然传播循环。
