猪脾转移因子对La Sota株鸡新城疫弱毒疫苗的免疫增强作用

Immunoenhancement on Newcastle disease virus La Sota strain attenuated vaccine by pig spleen transfer factor

摘要:

【目的】本文旨在研究猪脾转移因子（TF）对新城疫（ND）病毒弱毒疫苗La Sota株的免疫增强作用及机理，为兽医临床防控提供理论依据。【方法】以4种不同剂量La Sota疫苗株分别单独、与TF联合免疫SPF鸡，14 d后以ND病毒（NDV）参考强毒F₄₈E₉株（10^4.7 ELD₅₀）进行攻毒，采用蛋白质芯片技术测定鸡外周血IL-6、IL-10、IL-16和IL-21浓度，并以血凝抑制（HI）试验和荧光定量RT-PCR方法分别检测鸡ND HI抗体效价和F₄₈E₉株的病毒血症水平。【结果】攻毒保护试验表明，单独免疫10^5.17、10^4.17、10^3.17和10^2.17 EID₅₀剂量时疫苗攻毒保护率分别为100%、55%、0%和0%，半数保护量（PD₅₀）为12 023 EID₅₀；对应剂量联合免疫时疫苗攻毒保护率分别为100%、75%、0%和0%，PD₅₀为6 918 EID₅₀；对照组（非免疫有攻毒）和空白组（非免疫非攻毒）死亡率分别为100%和0%。对10^4.17 EID₅₀免疫剂量进一步检测分析表明，免疫后，联合免疫鸡IL-6、IL-10、IL-21和ND HI抗体效价（log₂x）比单独免疫最多时分别提高了254.95 pg/mL、62.10 pg/mL、1.51 pg/mL和2.6，其中ND HI抗体效价差异极显著（P<0.01）；攻毒后，联合免疫鸡IL-10、IL-16、IL-21和病毒血症阳性率比单独免疫最多时分别降低了428.61 pg/mL、167.81 pg/mL、1.48 pg/mL和20%，其中IL-16、IL-21差异极显著（P<0.01）。【结论】本文结果显示，TF可提高La Sota株弱毒疫苗的免疫保护率及免疫后IL-6、IL-10、IL-21介导的免疫应答、ND HI抗体效价，降低疫苗PD₅₀及攻毒后IL-16、IL-21介导的炎症反应、IL-10介导的免疫应答抑制作用、病毒血症。本文明确了TF对La Sota株弱毒疫苗具有较好的免疫增强作用，为疫苗免疫佐剂研发和ND防控提供参考。

Abstract:

[Objective] We evaluated the immunoenhancement effect and mechanism of pig spleen transfer factor (TF) on Newcastle disease virus (NDV) La Sota strain attenuated vaccine to provide a theoretical basis for the prevention and control of Newcastle disease (ND). [Methods] We inoculated La Sota strain alone and La Sota combined with TF into specific pathogen free (SPF) chickens at four different doses, and challenged SPF chickens by reference virulent NDV strain F₄₈E₉ (10^4.7 ELD₅₀) 14 days post vaccination. In addition, we determined the concentrations of IL-6, IL-10, IL-16, and IL-21 in chicken peripheral blood by protein chip technology, the hemagglutination inhibition (HI) antibody titer by HI assay, and the viremia level of F₄₈E₉ by RT-PCR. [Results] The challenge test showed that the protection rates of vaccination with La Sota strain alone at the doses of 10^5.17, 10^4.17, 10^3.17, and 10^2.17 EID₅₀ were 100%, 55%, 0%, and 0%, respectively, and the median protective dose (PD₅₀) was 12 023 EID₅₀. The protection rates of vaccination with La Sota strain combined with TF at the corresponding doses were 100%, 75%, 0%, and 0%, respectively, and the PD₅₀ was 6 918 EID₅₀. The mortality of control group (non-immunized but challenged) and blank group (non-immunized and non-challenged) were 100% and 0%. Upon vaccination at the dose of 10^4.17 EID₅₀, the IL-6, IL-10, IL-21, and ND HI antibody titer (log₂x) of the chicken exposed to combined vaccination increased at most by 254.95 pg/mL, 62.10 pg/mL, 1.51 pg/mL, and 2.6 (P<0.01), respectively, compared with those in the chicken vaccinated with La Sota strain alone. After challenge, the IL-10, IL-16, IL-21, and the viremia levels in the chicken under combined vaccination decreased at most by 428.61 pg/mL, 167.81 pg/mL (P<0.01), 1.48 pg/mL (P<0.01), and 20%, respectively, compared with those in the chicken vaccinated with La Sota strain alone. [Conclusion] TF improves the immune protection rate of NDV attenuated La Sota strain vaccine, the immune response mediated by IL-6, IL-10, and IL-21, and the ND HI antibody titer. In addition, TF reduces the PD₅₀, the inflammatory responses mediated by IL-16 and IL-21, the inhibition of immune response mediated by IL-10, and the viremia after challenge. It is clear that TF has a good immunoenhancement effect on the La Sota strain attenuated vaccine, which will provide a reference for research and development of vaccine adjuvant as well as prevention and control of ND.