The nucleoprotein (NP) is a highly conserved internal protein of the influenza virus, a major target for universal influenza vaccine. Our previous studies have proven NP-based subunit vaccine can provide partial protection in mice. It is reported that the protein transduction domain (PTD) TAT protein from human immunodeficiency virus-1 (HIV-1) is able to penetrate cells when added exogenous protein and could effectively enhance the immune response induced by the exogenous protein. In present study, the recombinant protein TAT-NP, a fusion of TAT and NP was effectively expressed in Escherichia coli and purified as a candidate component for an influenza vaccine. We evaluated the immunogenicity and protective efficacy of recombinant influenza TAT-NP vaccine by intranasal immunization. In vitro experiments showed that TAT-NP could efficiently penetrate into cells. Animal results showed that mice vaccinated with TAT-NP could not only induce higher levels of IgG and mucosal IgA, but also elicit a robust cellular immune response. Moreover, the TAT-NP fusion protein could significantly increase the protection of mice against lethal doses of homologous influenza virus PR8 and could also provide mice protection against a lethal dose challenge against heterosubtypic H9N2 and H3N2 influenza virus. In conclusion, the recombinant TAT-NP might be a universal vaccine candidate against influenza virus.

核蛋白 (NP) 是流感病毒的高度保守的内部蛋白质，是通用流感疫苗的主要靶点。我们之前的研究已经证明基于 NP 的亚单位疫苗可以为小鼠提供部分保护。据报道，来自人类免疫缺陷病毒1（HIV-1）的蛋白质转导结构域（PTD）TAT蛋白在加入外源蛋白后能够穿透细胞，并能有效增强外源蛋白诱导的免疫反应。在本研究中，重组蛋白 TAT-NP，TAT 和 NP 的融合蛋白在大肠杆菌中有效表达并纯化为流感疫苗的候选成分。我们通过鼻内免疫评估了重组流感 TAT-NP 疫苗的免疫原性和保护功效。体外实验表明，TAT-NP 可以有效地渗透到细胞中。动物结果表明，接种 TAT-NP 的小鼠不仅可以诱导更高水平的 IgG 和粘膜 IgA，还可以引发强大的细胞免疫反应。此外，TAT-NP 融合蛋白可以显着增加小鼠对致死剂量的同源流感病毒 PR8 的保护，还可以为小鼠提供对异亚型 H9N2 和 H3N2 流感病毒致死剂量攻击的保护。总之，重组TAT-NP可能是一种针对流感病毒的通用候选疫苗。