Inactivated H9N2 influenza vaccines required adjuvants to induce strong immune responses to protect poultry from the infections of H9N2 influenza viruses. Recently, positively charged nanoparticles-based adjuvant delivery systems have been extensively investigated as the novel vaccine adjuvant due to the protection antigens and drugs from degradation, promoting antigens and drugs uptake by antigen presenting cells (APCs), and inducing strong humoral and cellular immune responses. In this study, the immunostimulant Angelica sinensis polysaccharide (ASP) was encapsulated into Poly (lactic-co-glycolic acid) PLGA nanoparticles, and the Polyethylenimine (PEI) was coated on the nanoparticles to develop a novel adjuvant (ASP-PLGA-PEI). To further investigate the adjuvant activities of ASP-PLGA-PEI nanoparticles for H9N2 vaccines in chickens and compare the adjuvant activities of nanoparticles adjuvant and conventional adjuvants (Alum and oil-based adjuvant), the H9N2 antigen was incubated with three different adjuvants and then immunized with chickens to evaluate the ability of inducing humoral and cellular immune responses. The results revealed that compared to Alum adjuvant, ASP-PLGA-PEI nanoparticles adjuvant stimulated higher antibody responses, promoted the activation of CD4⁺ T cells and CD8⁺ T cells, increased the expression of Th1 cytokines IFN-γ. Compared to oil-based adjuvant (ISA-206), ASP-PLGA-PEI nanoparticles adjuvant induced comparable antibody immune responses at later period after immunization, improved the activation of CD4⁺ T cells and CD8⁺ T cells. Therefore, compared to Alum and oil-based adjuvant, the ASP-PLGA-PEI nanoparticles serve as an efficient adjuvant for H9N2 vaccine and have the potential to induce vigorous humoral and cellular immune responses in chickens.

灭活的H9N2流感疫苗需要佐剂来诱导强烈的免疫反应，以保护家禽免受H9N2流感病毒的感染。近来，由于保护抗原和药物免于降解，促进抗原和抗原呈递细胞（APC）吸收抗原并诱导强烈的体液和细胞免疫应答，因此基于正电荷的纳米粒子的佐剂递送系统已被广泛研究为新型疫苗佐剂。 。在这项研究中，免疫刺激剂当归将多糖（ASP）封装到聚（乳酸-乙醇酸共聚物）PLGA纳米粒子中，然后将聚乙烯亚胺（PEI）涂覆在纳米粒子上以开发新型佐剂（ASP-PLGA-PEI）。为了进一步研究ASP-PLGA-PEI纳米颗粒对鸡的H9N2疫苗的佐剂活性并比较纳米颗粒佐剂和常规佐剂（明矾和油基佐剂）的佐剂活性，将H9N2抗原与三种不同的佐剂一起孵育，然后进行免疫与鸡一起评估诱导体液和细胞免疫反应的能力。结果显示，与明矾佐剂相比，ASP-PLGA-PEI纳米颗粒佐剂刺激更高的抗体应答，促进CD4 ⁺ T细胞和CD8 ⁺的活化T细胞增加Th1细胞因子IFN-γ的表达。与油基佐剂（ISA-206）相比，ASP-PLGA-PEI纳米颗粒佐剂在免疫后的后期诱导了相当的抗体免疫反应，改善了CD4 ⁺ T细胞和CD8 ⁺ T细胞的活化。因此，与明矾和油基佐剂相比，ASP-PLGA-PEI纳米颗粒可作为H9N2疫苗的有效佐剂，并具有在鸡中诱导剧烈的体液和细胞免疫应答的潜力。