凡纳滨对虾消化道中白斑综合症病毒主要靶器官的鉴定

Identification of the main target organs of white spot syndrome virus(WSSV) in digest track of Litopenaeus vannamei

白斑综合症病毒（white spot syndrome virus,WSSV）是对虾养殖业中最具破坏力的致病病毒.本实验用含WSSV的克氏原螯虾（Procambarus clarkii）肌肉投喂健康凡纳滨对虾（Litopenaeus vannamei）,模拟自然条件下对虾经摄食感染WSSV的过程.在口服攻毒后不同时间分别取消化系统的不同器官通过荧光定量PCR测定各器官中病毒的拷贝数,发现攻毒后12~24 h病毒在食道或中肠中的病毒量仅增加了3~5倍,而在贲门胃和幽门胃中的病毒量增加了100倍以上.进一步的扫描电镜分析表明,病毒粒子对贲门胃和幽门胃内壁均具有很强的粘附能力,而对食道和中肠内壁的粘附能力很弱,且脱去了囊膜的WSSV核衣壳失去了与对虾消化道粘附的能力.以上结果说明WSSV经摄食后主要入侵的靶器官是胃,且病毒囊膜蛋白在病毒与宿主消化道器官的相互作用中起到了重要的作用.

White spot syndrome virus（ WSSV） is one of the most lethal pathogens in cultured shrimp. In this study,we mimicked the natural infective process of WSSV to Litopenaeus vannamei by feeding the shrimp with the muscle of WSSV infected Procambarus clarkia. The viral loads in the digest organs of infected shrimp were determined by real-time quantitative PCR. The results showed that from 12 h to 24 h post-infection,viral DNA copies in the stomach increased over 100 times,while there was only a three-fold increase in esophagus and a five-fold increase in midgut. Further investigation with scanning electronic microscopy indicated that WSSV had a much higher affinity to the inner surface of stomach than to esophagus and midgut. Moreover,in contrast to the intact virions,WSSV nuclear capsids could not attach to any of the digestive organ analyzed in this study. Therefore,we conclude that stomach is the main target organ of WSSV in the digest tract of penaeid shrimp,and the envelop proteins are essential for the interaction between WSSV and the host cells.