Song Jin-Ha, Son Seung-Eun, Kim Ho-Won, An Se-Hee, Lee Chung-Young, Kwon Hyuk-Joon, Choi Kang-Seuk
Laboratory of Avian Diseases, College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea.
Avian Influenza Research & Diagnostic Division, Animal and Plant Quarantine Agency, Gimcheon-si 39660, Republic of Korea.
Vaccines (Basel). 2024 Dec 30;13(1):22. doi: 10.3390/vaccines13010022.
Highly pathogenic (HP) H5Nx and low-pathogenicity (LP) H9N2 avian influenza viruses (AIVs) pose global threats to the poultry industry and public health, highlighting the critical need for a dual-protective vaccine. In this study, we generated a model PR8-derived recombinant H5N2 vaccine strain with hemagglutinin (HA) and neuraminidase (NA) genes from clade 2.3.2.1c H5N1 and Y439-like H9N2 viruses, respectively. To enhance the immunogenicity of the recombinant H5N2 vaccine strain, N-glycans of the HA2 subunit, NA, and M2e were modified. Additionally, we replaced M2e with avian M2e to enhance the antigenic homogeneity of AIVs for better protection. We also replaced PR8 PB2 with 01310 PB2, which is the PB2 gene derived from an LP H9N2 avian influenza virus, to eliminate pathogenicity in mammals. The productivity of the model vaccine strain (rvH5N2-aM2e-vPB2) in embryonated chicken eggs (ECEs), its potential risk of mammalian infection, and the immunogenicity associated with different inactivation methods (formaldehyde (F/A) vs. binary ethyleneimine (BEI)) were evaluated. The rvH5N2-aM2e-vPB2 strain demonstrated high productivity in ECEs and exhibited complete inhibition of replication in mammalian cells. Furthermore, compared with using F/A inactivation, inactivation using BEI significantly enhanced the immune response, particularly against NA. This enhancement resulted in increased virus neutralization titers, supporting its efficacy for dual protection against H5Nx and H9N2 avian influenza viruses. Furthermore, we demonstrated that M2e-specific immune responses, difficult to induce with inactivated vaccines, can be effectively elicited with live vaccines, suggesting a strategy to enhance M2e immunogenicity in whole influenza virus vaccines. Finally, the successful development of the model rH5N2 vaccine strain is described; this strain provides dual protection, has potential applicability in regions where avian influenza is endemic, and can be used to promote the development of versatile H5N2 recombinant vaccines for effective avian influenza control.
高致病性（HP）H5Nx和低致病性（LP）H9N2禽流感病毒（AIV）对家禽业和公共卫生构成全球威胁，凸显了对双保护疫苗的迫切需求。在本研究中，我们构建了一种源自PR8的重组H5N2疫苗株，其血凝素（HA）和神经氨酸酶（NA）基因分别来自2.3.2.1c分支H5N1和Y439样H9N2病毒。为增强重组H5N2疫苗株的免疫原性，对HA2亚基、NA和M2e的N-聚糖进行了修饰。此外，我们用禽源M2e替换了M2e，以增强AIV的抗原同源性，实现更好的保护。我们还用01310 PB2替换了PR8 PB2，01310 PB2是源自低致病性H9N2禽流感病毒的PB2基因，以消除在哺乳动物中的致病性。评估了模型疫苗株（rvH5N2-aM2e-vPB2）在鸡胚（ECE）中的生产能力、其感染哺乳动物的潜在风险以及与不同灭活方法（甲醛（F/A）与双乙烯亚胺（BEI））相关的免疫原性。rvH5N2-aM2e-vPB2株在ECE中表现出高生产能力，并且在哺乳动物细胞中显示出完全抑制复制。此外，与使用F/A灭活相比，使用BEI灭活显著增强了免疫反应，尤其是针对NA的免疫反应。这种增强导致病毒中和滴度增加，支持其对H5Nx和H9N2禽流感病毒的双保护效力。此外，我们证明了难以用灭活疫苗诱导的M2e特异性免疫反应可以用活疫苗有效引发，这提示了一种在全流感病毒疫苗中增强M2e免疫原性的策略。最后，描述了模型rH5N2疫苗株的成功研发；该毒株提供双保护，在禽流感流行地区具有潜在适用性，可用于推动通用H5N2重组疫苗的研发，以有效控制禽流感。
