鸡胚接种鸡白介素18重组质粒对IBDVDNA疫苗免疫增强作用的研究

Immunoenhancement on IBDV DNA vaccine by embryo vaccination with plasmid DNA encoding chicken interleukin-18

用鸡白细胞介素18(ChIL-18)重组质粒(pCI-ChIL-18)接种18胚龄SPF鸡胚,利用适时荧光定量PCR方法对试验鸡不同时间点的动态变化进行检测。检测结果表明,胚胎接种pCI-ChIL-18使ChIL-18在鸡血液中早期持续高浓度存在,能促进鸡脾脏和法氏囊中ChIL-18基因的大量表达。用pCI-ChIL-18与传染性法氏囊病病毒(IBDV)多聚蛋白DNA疫苗分别免疫18胚龄SPF鸡胚,设1日龄雏鸡肌肉免疫对照组和空白对照组,2周龄时二免,6周龄时用IBDV标准强毒株BC6/85攻击。结果表明,胚胎免疫pCI-ChIL-18能显著促进试验鸡T、B淋巴细胞的早期增殖反应,增强IBDV多聚蛋白DNA疫苗诱导的早期抗体水平及其对强毒攻击的保护力。并进一步证明胚胎免疫pCI-ChIL-18对IBDV多聚蛋白DNA疫苗的早期免疫效果具有显著的增强作用(P<0.05)。

The plasmid DNA encoding chicken interleukin-18 was inoculated to 18-day-old chick embryos, and monitored for the copy numbers presented in peripheral blood, spleen and bursa of fabricius at different time points by Real-time PCR. The results showed that pCI-ChIL-18 inoculation via allantoic cavity resulted in high level expression of ChIL-18 in nonage spleen and bursa of fabricius. To further test the immune enhancement of ChIL-18, pCI-ChIL-18 was coadministrated with infectious bursal disease virus （IBDV） DNA vaccine to 18-day-old chick embryos, then boosted after two weeks, followed by challenge with virulent IBDV four weeks later. The results showed that ChIL-18 could significantly enhance the nonage proliferation responses of T lymphoeytes from spleen and B lymphocytes from bursa. It also raised the nonage neutralization antibody level and enhanced the protection against virulent IBDV induced by DNA vaccine. Therefore the nonage immune responding to IBDV DNA vaccine was highly enhanced by embryonic co-administration with ChIL-18 （P〈0.05）.