Veterinary disease diagnostic center, Shanghai Animal Disease Control Center, Shanghai, China.
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China.
Influenza Other Respir Viruses. 2017 Nov;11(6):518-524. doi: 10.1111/irv.12472. Epub 2017 Aug 24.
Avian influenza viruses represent a growing threat of an influenza pandemic. The co-circulation of multiple H9N2 genotypes over the past decade has been replaced by one predominant genotype-G57 genotype, which displays a changed antigenicity and improved adaptability in chickens. Effective H9N2 subtype avian influenza virus vaccines for poultry are urgently needed.
In this study, we constructed H9N2 subtype avian influenza virus-like particle (VLP) and evaluated its protective efficacy in specific pathogen-free (SPF) chickens to lay the foundation for developing an effective vaccine against influenza viruses.
Expression of influenza proteins in VLPs was confirmed by Western blot, hemagglutination inhibition (HI), and neuraminidase inhibition (NI). The morphology was observed by electron microscopy. A group of 15 three-week-old SPF chickens was divided into three subgroups of five chickens immunized with VLP, commercial vaccine, and PBS. Challenge study was performed to evaluate efficacy of VLP vaccine.
The hemagglutinin (HA) and neuraminidase (NA) proteins were co-expressed in the infected cells, self-assembled, and were released into the culture medium in the form of VLPs of diameter ~80 nm. The VLPs exhibited some functional characteristics of a full influenza virus, including hemagglutination and neuraminidase activity. In SPF chickens, the VLPs elicited serum antibodies specific for H9N2 and induced a higher HI titer (as detected by a homologous antigen) than did a commercial H9N2 vaccine (A/chicken/Shanghai/F/1998). Viral shedding from VLP vaccine subgroup was reduced compared with commercial vaccine subgroup and control subgroup.
禽流感病毒是流感大流行的潜在威胁。在过去十年中，多种 H9N2 基因型的共同流行已被一种主要基因型-G57 基因型所取代，这种基因型在鸡中显示出改变的抗原性和更好的适应性。迫切需要针对家禽的有效 H9N2 亚型禽流感病毒疫苗。
本研究构建了 H9N2 亚型禽流感病毒样颗粒（VLP），并评估了其在无特定病原体（SPF）鸡中的保护效力，为开发针对流感病毒的有效疫苗奠定了基础。
通过 Western blot、血凝抑制（HI）和神经氨酸酶抑制（NI）试验确认 VLP 中流感蛋白的表达。通过电子显微镜观察其形态。将 15 只 3 周龄的 SPF 鸡分为 3 组，每组 5 只，分别免疫 VLP、商业疫苗和 PBS。进行攻毒试验以评估 VLP 疫苗的效力。
感染细胞中共同表达了血凝素（HA）和神经氨酸酶（NA）蛋白，它们自组装并以直径约 80nm 的 VLP 形式释放到培养基中。VLP 表现出一些全流感病毒的功能特征，包括血凝和神经氨酸酶活性。在 SPF 鸡中，VLP 诱导产生了针对 H9N2 的血清抗体，并引起了比商业 H9N2 疫苗（A/chicken/Shanghai/F/1998）更高的 HI 滴度（通过同源抗原检测）。与商业疫苗组和对照组相比，VLP 疫苗组的病毒脱落量减少。
