不同剂量双表达蛋白VP2-IL-18免疫原性的比较

Comparison of Immunogenicity of Double Expressed IBDV VP2-IL-18 Protein with Bac-to-Bac System

【目的】基于IL-18具有双向免疫调节作用,摸索利用Bac-to-Bac系统双表达的蛋白VP2-IL-18的最佳免疫增强剂量。【方法】采用腿部肌肉多点注射方法将不同剂量VP2-IL-18免疫14日龄SPF鸡,14 d后加强免疫1次;一免后第0、7、14、21、28和35天采集外周血检测ELISA抗体效价和CD4^(+)T、CD8^(+)T细胞的数量;一免后第35天用vvIBDV-GX8/99毒株进行攻毒。【结果】各剂量VP2-IL-18免疫雏鸡后均能提高抗体滴度,促进CD4^(+)T和CD8^(+)T淋巴细胞增殖以及提高攻毒保护率,且200μg VP2-IL-18免疫组效果最佳,要优于低剂量免疫组和高剂量免疫组,差异显著(P<0.05)。【结论】VP2-IL-18具有良好的免疫原性,且200μg为最佳免疫剂量,不呈现高剂量依赖。

【Objective】Based on the double-directional immunomodulatory effect of IL-18,the optimal immune enhancement dose of double expressed VP2-IL-18 proteinwith Bac-to-Bac system was explored.【Method】The 14-day-old chickens were immunized multi-point intramuscularly with VP2-IL-18,and then boosted 14 days later.The bloods at days 0,7,14,21,28 and 35 post-first-inoculation were collected to detect the ELISA antibody titer and the number of CD4^(+),CD8^(+)T cells.35 days after first boosting,chickens were challenged by very virulent IBDV-GX8/99 strain.【Result】The results showed that VP2-IL-18 could increase anti-IBDV antibody titer,promote CD4^(+)T,CD8^(+)T cell proliferation and enhance the protective efficacy.However,200μg VP2-IL-18 showed better effect than that of low-dose immunity groups and high-dose immunity groups(P<0.05).【Conclusion】These results demonstrated that VP2-IL-18 can lead to a fine immunogenity and 200μg is the best dose,which exhibits not high-dose-dependent.