口服特异性卵黄抗体对凡纳滨对虾抗WSSV感染的免疫保护效果

Protective effects of oral specific egg yolk immunoglobulins (IgY) against white spot syndrome virus (WSSV) infection in Pacific white shrimp (Litopenaeus vannamei)

关键词:  卵黄抗体  凡纳滨对虾  白斑综合征病毒  免疫酶活力  免疫基因表达  抗病力

Key words:  Immunoglobulin of yolk (IgY)  Litopenaeus vannamei  White spot syndrome virus (WSSV)  Immune enzyme activity  Immune gene expression  Disease resistance

摘要:

为探讨特异性卵黄抗体对凡纳滨对虾(Litopenaeus vannamei)抗白斑综合征病毒(white spot syndrome virus, WSSV)的免疫保护机制及效果，本研究以添加不同剂量WSSV卵黄抗体制剂(0、0.2%和0.5%)的饲料投喂凡纳滨对虾幼虾，免疫28 d后使用WSSV进行人工感染，测定感染对虾的肝胰腺免疫酶活力和免疫基因表达水平，以及感染后14 d内对虾的存活率。结果显示，WSSV感染3 d后，与未添加卵黄抗体制剂的对照组相比，0.2%免疫组对虾肝胰腺的超氧化物歧化酶(SOD)和酚氧化酶(PO)活力显著升高，酸性磷酸酶(ACP)和碱性磷酸酶(AKP)活力显著降低，热休克蛋白70基因(Hsp70)表达水平显著升高，凝集素基因(lectin)和β-1,3-葡聚糖结合蛋白–脂蛋白基因(β-GBP-HDL)表达水平显著降低；0.5%免疫组对虾肝胰腺的SOD活力显著升高，ACP和AKP活力显著降低，Hsp70基因表达水平显著升高，β-GBP-HDL基因表达水平显著降低。人工感染实验结果显示，WSSV感染14 d后，0.2%和0.5%免疫组对虾的存活率分别为48.89%和87.78%，均显著高于对照组(存活率为0)，且0.5%免疫组对虾存活率显著高于0.2%免疫组。特异性卵黄抗体制剂能在一定程度上改变发病的进程，延迟对虾的发病和死亡时间，提高同期存活率。研究表明，口服特异性卵黄抗体制剂可以调节对虾肝胰腺免疫酶活力和免疫基因表达水平，显著提高凡纳滨对虾抗WSSV感染的能力。本研究为卵黄抗体抗WSSV感染机制的研究提供了参考，也为在生产上使用卵黄抗体防控WSSV感染提供了科学依据。

Abstract:

The aim of this study was to explore the immunoprotective mechanism and protective effects of oral specific egg yolk immunoglobulin (IgY) against white spot syndrome virus (WSSV) infection in Pacific white shrimp (Litopenaeus vannamei). Different doses of WSSV IgY agent (0, 0.2%, and 0.5%) were added to shrimp feeds and administered to juvenile L. vannamei for 28 days. The survival rate of juveniles was measured within 14 days of artificial infection with WSSV. The activity of immune enzymes and the relative expression levels of immune genes in shrimp hepatopancreas were measured after 3 days of WSSV infection. The results showed that compared with the control group without IgY, the 0.2% IgY agent group showed significantly higher enzyme activity by superoxide dismutase (SOD) and phenoloxidase (PO), and significantly lower enzyme activity by acid phosphatase (ACP) and alkaline phosphatase (AKP). The relative expression level of heat shock protein 70 gene (Hsp70) also significantly increased, while the relative expression levels of lectin gene (lectin) and β-1,3-glucan binding protein-lipoprotein gene (β-GBP-HDL) significantly decreased in the 0.2% IgY agent group. SOD activity significantly increased while PO activity did not change significantly, while ACP and AKP activities decreased in the 0.5% IgY agent group. The relative expression level of Hsp70 also significantly increased, and the relative expression level of lectin did not significantly change, while the relative expression level of β-GBP-HDL significantly decreased in the 0.5% IgY agent group. The artificial infection results showed that after 14 days of WSSV infection, the survival rates of shrimp in the 0.2% and 0.5% IgY agent groups, and the control group were 48.89%, 87.78%, and 0, respectively. The survival rate of shrimp in the 0.2% and 0.5% IgY agent groups was significantly higher than that in the control group, and the survival rate of shrimp in the 0.5% IgY agent group was also significantly higher than that in the 0.2 % IgY agent group. Specific IgY agents can change the course of a disease, delay disease onset and death of immune shrimp, and significantly improve the survival rate of shrimp over a certain period. The results showed that oral specific IgY agents could affect the activity of immune enzymes and the expression level of immune genes in the hepatopancreas of L. vannamei, significantly improving their ability to resist WSSV infection. This study provides a basis for the application of IgY agents in the prevention and control of WSSV infection, and also provides a reference for research on the anti-WSSV infection mechanism of IgY agents.