Cao Zhiming, Wang Shiao Y, Breeland Verlee, Moore Anne-Marie, Lotz Jeffrey M
Department of Biological Sciences, The University of Southern Mississippi, 118 College Dr. # 5018, Hattiesburg, Mississippi 39406, USA.
Dis Aquat Organ. 2010 Sep 2;91(2):97-103. doi: 10.3354/dao02258.
Taura syndrome is an economically important disease that can cause catastrophic losses of farmed shrimp. Without effective treatments for Taura syndrome virus (TSV), one approach to managing the problem is to selectively breed shrimp populations with increased disease resistance. To better understand why some shrimp can survive exposure to TSV, information is needed on how viral loads progress and persist following infection. Data reported here show that mortalities occurring mostly within 1 wk of infection are associated with high viral titers, and titers as high as 10(8.7) genome copies per microl hemolymph can persist for up to 3 wk in survivors. Thereafter, and up to approximately 9 wk post-exposure, most surviving shrimp remain chronically infected with TSV loads ranging from 10(4) to 10(8) genome copies per microl hemolymph. Challenging shrimp from families with varying TSV resistance showed that in shrimp from less resistant families, the TSV load in hemolymph increased earlier and reached higher peaks than in shrimp from more resistant families. Although TSV loads in moribund shrimp from families differing in resistance did not differ significantly, infection loads among survivors were lower in shrimp from more resistant families. Taken together, the data suggest that lethal infection loads can occur in both more and less susceptible shrimp and that survivors represent shrimp in which viral expansion is better contained.
桃拉综合征是一种在经济上具有重要影响的疾病，可导致养殖虾类遭受灾难性损失。由于目前尚无针对桃拉综合征病毒（TSV）的有效治疗方法，解决这一问题的一种途径是选择性培育抗病能力更强的虾群。为了更好地理解为何有些虾在接触TSV后能够存活，需要了解感染后病毒载量的变化过程及持续情况。本文报告的数据显示，大多在感染后1周内发生的死亡与高病毒滴度有关，在存活虾中，每微升血淋巴中高达10(8.7)个基因组拷贝的病毒滴度可持续长达3周。此后，直至接触病毒后约9周，大多数存活虾仍长期感染TSV，血淋巴中的病毒载量范围为每微升10(4)至10(8)个基因组拷贝。对来自不同TSV抗性家族的虾进行攻毒试验表明，抗性较低家族的虾，其血淋巴中的TSV载量比抗性较高家族的虾更早升高且达到更高峰值。虽然来自抗性不同家族的濒死虾的TSV载量无显著差异，但抗性较高家族的存活虾中的感染载量较低。综合来看，这些数据表明，易感性高和低的虾都可能出现致死性感染载量，而存活下来的虾表明其体内病毒的扩散得到了更好的控制。
