鸡白细胞介素2口服免疫佐剂增强传染性法氏囊病病毒DNA疫苗免疫效果的研究

Enhancement of immunogenicity of DNA vaccine against infectious bursal disease virus by co-delivery with oral vaccine encoding chicken interleukin-2.

将含萧山鸡白细胞介素2基因的真核表达质粒pCI-IL-2的减毒鼠伤寒沙门氏菌ZJ111(ZJ111/pCI-IL-2)口服接种小鼠和雏鸡,并与传染性法氏囊病病毒(IBDV)DNA疫苗联合免疫雏鸡观察其免疫效力.结果表明:利用减毒沙门氏菌作为载体的鸡白细胞介素2口服免疫增强剂具有相对的安全性.重组ZJ111/pCI-IL-2菌能明显增强IBDV DNA疫苗对强毒株攻击保护率;增强IBDV DNA疫苗诱导的抗体的效价(P<0.05);增强IBDV DNA疫苗所诱导的T淋巴细胞和B淋巴细胞的增殖反应(P<0.05).上述结果初步表明以减毒沙门氏菌为载体的白细胞介素2免疫增强剂具有良好的安全性和免疫增强作用,为研制低成本、实用化的禽类口服免疫增强剂奠定了基础.

Mice and 14-day-old chickens were orally inoculated with the recombinant attenuated Salmonella typhimurium strain ZJ111 carrying pCI-IL-2 expression plasmid encoding the Interleukin II protein. The results showed the ZJ111/pCI-IL-2 was relatively safe. Fourteen-day-old non-immunized chickens were co- administrated orally and intradermally with DNA vaccine and ZJ111/pCI-IL-2 at three dosage levels （10^7 cfu, 10^8 cfu, 10^9 cfu）, and boosted two weeks later. Control groups（challenge control, normal control, DNA vaccine control） were included. The chickens were challenged with virulent infectious bursal disease virus （IBDV） seventeen days post-boosting. The results showed that protective responses and neutralization antibody response of DNA vaccine co-administrated with chicken interleukin-2 （IL-2） were much higher than those of injected with DNA vaccine alone, Futhermore, the T lymphocyte proliferation response of thymus and spleen, and the B lymphocyte proliferation response of bursa induced by DNA vaccine can be significantly enhanced by chicken IL- 2, These results obviously indicated that chicken IL-2 was a strong adjuvant can be significantly enhance the immunogenicity of IBDV DNA vaccine.