ABSTRACT

Most of the current approaches to influenza vaccine design focus on antibodies against influenza (HA). However, these influenza vaccines typically provide strain-specific protection against mostly homologous subtypes. There is an urgent need to develop a universal vaccine that confers cross-protection against influenza viruses. Of note, the HA stalk domain (HAsd) is a promising target for such an influenza vaccine. In this study, we generated recombinant Lactococcus lactis (L. lactis)/pNZ8150-phosphatidylglycerophosphate synthetase A (pgsA)-HAsd, in which pgsA was used as an anchor protein, and investigated the immunogenicity of HAsd in a mouse model by oral administration without the use of a mucosal adjuvant. Compared with L. lactis/pNZ8150-pgsA, mice were orally vaccinated with L. lactis/pNZ8150-pgsA-HAsd and then produced strong humoral and mucosal immune responses. Importantly, L. lactis/pNZ8150-pgsA-HAsd provided cross-protection against H5N1, H3N2 and H1N1 virus infections. Our data support the hypothesis that HAsd presented on the surface of L. lactis can provide cross-protective immunity against divergent influenza A viruses. Taken together, these findings suggest that L. lactis/pNZ8150-pgsA-HAsd can be considered an alternative approach to developing a novel universal vaccine during an influenza A pandemic.

Abbreviations: HA, HAsd, HA stalk domain; L. lactis, Lactococcus lactis; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; IFA, immunofluorescence assay; PBS, phosphate-buffered saline; pgsA, phosphatidylglycerophosphate synthetase A; SPF, specific pathogen-free; CFU, colony-forming unit; BSL-3, biosafety level-3 laboratory; TCID₅₀, 50% tissue culture infective dose; ELISA, enzyme-linked immunosorbent assay; OD, optical density; LTB, liable enterotoxin B subunit; CTB, cholera toxin B subunit.

摘要

目前大多数流感疫苗设计方法都集中在针对流感 (HA) 的抗体上。然而，这些流感疫苗通常提供针对大多数同源亚型的菌株特异性保护。迫切需要开发一种通用疫苗，以提供针对流感病毒的交叉保护。值得注意的是，HA 茎结构域 (HAsd) 是此类流感疫苗的一个有希望的目标。在这项研究中，我们产生了重组乳酸乳球菌( L. lactis )/pNZ8150-磷脂酰甘油磷酸合成酶 A (pgsA)-HAsd，其中 pgsA 用作锚定蛋白，并通过口服给药研究了小鼠模型中 HAsd 的免疫原性，而没有使用粘膜佐剂。与乳酸乳球菌相比/pNZ8150-pgsA，小鼠口服乳酸乳球菌/pNZ8150-pgsA-HAsd，然后产生强烈的体液和粘膜免疫反应。重要的是，乳酸乳球菌/pNZ8150-pgsA-HAsd 提供了针对 H5N1、H3N2 和 H1N1 病毒感染的交叉保护。我们的数据支持这样的假设，即存在于乳酸乳球菌表面的 HAsd可以提供针对不同甲型流感病毒的交叉保护免疫。综上所述，这些发现表明乳酸乳球菌/pNZ8150-pgsA-HAsd 可被视为在甲型流感大流行期间开发新型通用疫苗的替代方法。

缩写： HA、HAsd、HA茎域；乳酸乳球菌，乳酸乳球菌；SDS-PAGE，十二烷基硫酸钠-聚丙烯酰胺凝胶电泳；IFA，免疫荧光测定；PBS，磷酸盐缓冲盐水；pgsA，磷脂酰甘油磷酸合成酶 A；SPF，无特定病原体；CFU，菌落形成单位；BSL-3，生物安全三级实验室；TCID ₅₀，50% 组织培养感染剂量；ELISA，酶联免疫吸附测定；OD，光密度；LTB，易肠毒素B亚单位；CTB，霍乱毒素B亚基。