凡纳滨对虾感染与暴发白斑综合征(WSD)的密度因素分析

摘要

White spot syndrome viruse (WSSV) carried by cultured Litopenaeus vannamei in several districts in Shanghai, Jiangsu and Hainan in China was detected by polymerase chain reaction (PCR). Data showed that up to 40％-58％ of the sampled shrimp were infected with WSSV, indicating that the infection rate of WSSV in L. vannamei was still high in the latest years even if the shrimp were of SPF or SPR origin. As a possible risk factor associated with the consequence, the current aquaculture model characterized by high culture density, was considered in this study, and the roles of high and low culture density during shrimp infection with WSSV and outbreak of WSD were investigated, respectively. Analysis of the shrimp mortality indicated that the mortality of shrimp cultured in the high density was 96.9％ (with salinity unchanged) or 98.1％ (with abrupt salinity reduction), whereas that of those cultured in the low density was 5.0 ％ (with salinity unchanged) or 26.7 ％ ( with abrupt salinity reduction), suggesting that the difference in mortality between shrimp cultured with high and low density was remarkable;data from real time PCR also indicated that WSSV multiplicated much more quickly in shrimp cultured in the high density than that in the low density. Taken together, the present study demonstrates that the high culture density plays an important role during shrimp infection with WSSV and outbreak of WSD in current intensive aquaculture systems.%采用PCR检测技术分别对上海、江苏、海南部分养殖地区凡纳滨对虾携带重要病毒性病原--白斑综合征病毒(WSSV)的情况进行了调查分析.结果显示40%～58%的受检测对虾携带WSSV,表明近年在养殖SPF(无特定病原)甚至SPR(抗特定病原)亲虾子代的情况下,凡纳滨对虾的WSSV感染率仍然很高.为探讨现行集约化、高密度养殖模式对凡纳滨对虾感染与暴发白斑综合征(white spot disease,WSD)的影响,设高、低密度2个养殖模拟试验组,每组设盐度恒定和突降2种处理.对虾死亡率分析显示,高密度组虾死亡率分别为96.9%(盐度恒定)和98.1%(盐度突降),低密度组分别为5.0%(盐度恒定)和26.7%(盐度突降),差异显著;WSSV定量PCR检测分析也表明,在捕捉、盐度变化等因子的共同作用下,高密度组对虾体内WSSV携带量随着暂养时间推移而迅速增加,而同条件低密度组变化幅度很小.研究结果表明,集约化养殖模式下的高密度因素对WSSV感染与疾病暴发起促进作用.