Virus Research & Development Laboratory, Department of Virus & Microbiological Special Diagnostics Statens Serum Institut, Copenhagen, Denmark.
Research Unit of Infectious Diseases, Clinical Institute, University of Southern Denmark, Odense, Denmark.
Front Immunol. 2023 May 29;14:1200718. doi: 10.3389/fimmu.2023.1200718. eCollection 2023.
Neuraminidase (NA) accounts for approximately 10-20% of the total glycoproteins on the surface of influenza viruses. It cleaves sialic acids on glycoproteins, which facilitates virus entry into the airways by cleaving heavily glycosylated mucins in mucus and the release of progeny virus from the surface of infected cells. These functions make NA an attractive vaccine target. To inform rational vaccine design, we define the functionality of influenza DNA vaccine-induced NA-specific antibodies relative to antigenic sites in pigs and ferrets challenged with a vaccine-homologous A/California/7/2009(H1N1)pdm09 strain. Sera collected pre-vaccination, post-vaccination and post-challenge were analyzed for antibody-mediated inhibition of NA activity using a recombinant H7N1 virus. Antigenic sites were further identified with linear and conformational peptide microarrays spanning the full NA of A/California/04/2009(H1N1)pdm09. Vaccine-induced NA-specific antibodies inhibited the enzymatic function of NA in both animal models. The antibodies target critical sites of NA such as the enzymatic site, second sialic binding site and framework residues, shown here by high-resolution epitope mapping. New possible antigenic sites were identified that potentially block the catalytic activity of NA, including an epitope recognized solely in pigs and ferrets with neuraminidase inhibition, which could be a key antigenic site affecting NA function. These findings show that our influenza DNA vaccine candidate induces NA-specific antibodies that target known critical sites, and new potential antigenic sites of NA, inhibiting the catalytic activity of NA.
神经氨酸酶（NA）约占流感病毒表面总糖蛋白的 10-20%。它裂解糖蛋白上的唾液酸，通过裂解黏液中高度糖基化的粘蛋白以及从感染细胞表面释放子代病毒，促进病毒进入气道。这些功能使 NA 成为有吸引力的疫苗靶标。为了提供合理的疫苗设计信息，我们定义了流感 DNA 疫苗诱导的 NA 特异性抗体相对于用疫苗同源 A/加利福尼亚/7/2009(H1N1)pdm09 株攻毒的猪和雪貂中的抗原表位的功能。在接种前、接种后和攻毒后采集的血清，使用重组 H7N1 病毒分析抗体介导的 NA 活性抑制情况。使用线性和构象肽微阵列进一步鉴定抗原表位，涵盖 A/加利福尼亚/04/2009(H1N1)pdm09 的全长 NA。疫苗诱导的 NA 特异性抗体在两种动物模型中均抑制了 NA 的酶功能。抗体针对 NA 的关键位点，如酶位点、第二个唾液酸结合位点和框架残基，这里通过高分辨率表位作图进行了显示。鉴定出了新的可能的抗原表位，这些表位可能阻断 NA 的催化活性，包括在猪和雪貂中仅被神经氨酸酶抑制识别的表位，这可能是影响 NA 功能的关键抗原表位。这些发现表明，我们的流感 DNA 疫苗候选物诱导的 NA 特异性抗体可靶向已知的关键位点和 NA 的新潜在抗原表位，抑制 NA 的催化活性。
