自然养殖水体投喂CpG ODN和表面展示VP28的解脂耶罗维亚酵母对凡纳滨对虾(Litopenaeus vannamei)抗WSSV的免疫保护作用

Oral Administration of CpG ODNs and Yarrowia lipolytica Harboring VP28 in Farm Ponds to Protect Shrimp From White Spot Syndrome Virus Infection

用添加CpG寡聚核苷酸(CpG ODN)和表面展示VP28的解脂耶罗维亚酵母(VP28-yl)的饵料投喂凡纳滨对虾,进行田间中试实验。投喂30 d后进行WSSV感染实验,评估其对凡纳滨对虾的免疫保护作用。投喂实验结束后,CpG ODN投喂组对虾的相对增重率达到(65.8±7.8)%(P<0.05),这暗示CpG ODN可能具有促生长作用。WSSV攻毒后,CpG ODN和VP28-yl投喂组对虾中WSSV拷贝数与对照组相比均显著降低(P<0.05),相对免疫保护率分别可达到26.7%和36.7%。在投喂结束和WSSV刺激后,CpG ODN组对虾中的呼吸爆发水平均显著升高(P<0.05)。而在VP28-yl投喂组,WSSV引起的细胞凋亡则显著受到抑制(P<0.05)。此外,WSSV刺激后,STAT基因在CpG ODN组和VP28-yl组对虾中的表达水平均显著上调(P<0.05),分别在第5天和第3天达到最大值,而对照组中则显著下调。研究结果表明,CpG ODN和VP28-yl增强了凡纳滨对虾抗病毒免疫力,对养殖对虾病毒性疫病的防控具有显著作用,可以作为免疫增强剂添加在饵料中,具有在养殖生产中推广使用的前景。

Frequent outbreaks of viral and bacterial diseases have caused severe economic loss in shrimp farming that has been an important part in aquaculture. The white spot syndrome is one of the most harmful diseases in shrimp culture. It is crucial to develop novel strategies that efficiently protect shrimp against WSSV. In this study, we performed oral administration of diet supplemented with CpG ODNs prepared with large-scale fermentation and Yarrowia lipolytica harboring VP28 （VP28-yl） to farmed Litopenaeus vannamei. After 30-day feeding we challenged the shrimp with WSSV to evaluate the protective effects of CpG ODN and VP28-yl. Shrimp fed with CpG ODN displayed a relative weight gain of （65.8±7.8）% （P〈0.05）, indicating that CpG ODN might promote the growth of shrimp. After the WSSV challenge, the copies of WSSV in shrimp fed with CpG ODN and VP28-yl were both significantly less compared to the control （P〈0.05）, and the RPS were 26.7% and 36.7% respectively. The respiratory burst level of shrimp fed with CpG ODN was increased after feeding trial and WSSV challenge. After the WSSV challenge, there was a gradual increase in the apoptosis of haemocytes in the control shrimp. In the contrast, the apoptosis of haemocytes in shrimp fed with VP28-yl was significantly suppressed. Moreover, the expression of STAT mRNA in shrimp fed with CpG ODN and VP28-yl was significantly increased post the WSSV challenge （P〈0.05）, and there was an opposite trend in the control group （P〈0.05）. These results suggested that oral administration of CpG ODN and VP28-yl could enhance the antiviral immunity against WSSV, and thus help control viral diseases. These two immunoactive substances could be potentially new therapies in shrimp aquaculture industry.