Biological and Protective Properties of Immune Sera Directed to the Influenza Virus Neuraminidase
Biological and Protective Properties of Immune Sera Directed to the Influenza Virus Neuraminidase
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DOI：
10.1128/jvi.02949-14
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发表时间：
2015-02-01
影响因子：
5.4
通讯作者：
Zimmer, Gert
中科院分区：
文献类型：
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作者：
Halbherr, Stefan J.;Ludersdorfer, Thomas H.;Zimmer, Gert
甲型流感病毒的囊膜含有血凝素(HA)和神经氨酸酶(NA)两大抗原。常规流感病毒疫苗诱导的中和抗体主要针对HA球状头部，这是一个容易发生广泛抗原漂移的区域。针对NA的抗体诱导水平要低得多，这可能是由于HA抗原的免疫优势所致。尽管针对NA的抗体可能通过抑制糖蛋白的唾液酸酶功能来影响病毒的释放，但在过去的疫苗设计中，该抗原在很大程度上被忽略了。在这项研究中，我们表征了由编码NA的重组RNA复制子颗粒免疫产生的单特异性免疫血清的保护特性。这些免疫血清以安娜亚型特异性和HA亚型非依赖性的方式抑制血凝，并干扰MDCK细胞的感染。此外，它们还抑制相同甚至不同NA亚型的各种流感病毒的唾液酸酶活性。在此基础上，抗NA免疫血清以浓度依赖的方式抑制H5N1高致病性禽流感病毒和HA/NA假型病毒在MDCK细胞中的传播。用NA重组复制子颗粒免疫鸡后，感染低致病力禽流感病毒后，炎性血清标志物显著降低，病毒脱落受到限制或消除。这些发现表明，NA抗体可以通过干扰病毒的附着和输出来抑制病毒的传播。我们的结果强调了高质量的NA抗体在控制流感病毒复制方面的潜力，并强调了NA作为疫苗抗原的潜力。重要的是，甲型流感病毒的神经氨酸酶是一种唾液酸酶，起着破坏受体的作用，促进后代病毒从感染细胞中释放。在这里，我们证明了单特异性抗NA免疫血清不仅抑制唾液酸酶活性，而且抑制流感病毒的血凝和对MDCK细胞的感染，这表明NA抗体可以干扰病毒的附着。抑制病毒释放和病毒结合这两个过程，可能解释了为什么NA抗体有效地阻止了病毒在体外和体内的传播。抗NA免疫血清在血凝抑制试验中表现出比抗HA血清更广泛的反应性，在唾液酸酶抑制试验中表现出跨亚型活性。NA抗体的这些显著特征突显了NA抗原对于开发下一代流感病毒疫苗的重要性。
The envelope of influenza A viruses contains two large antigens, hemagglutinin (HA) and neuraminidase (NA). Conventional influenza virus vaccines induce neutralizing antibodies that are predominantly directed to the HA globular head, a domain that is subject to extensive antigenic drift. Antibodies directed to NA are induced at much lower levels, probably as a consequence of the immunodominance of the HA antigen. Although antibodies to NA may affect virus release by inhibiting the sialidase function of the glycoprotein, the antigen has been largely neglected in past vaccine design. In this study, we characterized the protective properties of monospecific immune sera that were generated by vaccination with recombinant RNA replicon particles encoding NA. These immune sera inhibited hemagglutination in an NA subtype-specific and HA subtype-independent manner and interfered with infection of MDCK cells. In addition, they inhibited the sialidase activities of various influenza viruses of the same and even different NA subtypes. With this, the anti-NA immune sera inhibited the spread of H5N1 highly pathogenic avian influenza virus and HA/NA-pseudotyped viruses in MDCK cells in a concentration-dependent manner. When chickens were immunized with NA recombinant replicon particles and subsequently infected with low-pathogenic avian influenza virus, inflammatory serum markers were significantly reduced and virus shedding was limited or eliminated. These findings suggest that NA antibodies can inhibit virus dissemination by interfering with both virus attachment and egress. Our results underline the potential of high-quality NA antibodies for controlling influenza virus replication and place emphasis on NA as a vaccine antigen.IMPORTANCE The neuraminidase of influenza A viruses is a sialidase that acts as a receptor-destroying enzyme facilitating the release of progeny virus from infected cells. Here, we demonstrate that monospecific anti-NA immune sera inhibited not only sialidase activity, but also influenza virus hemagglutination and infection of MDCK cells, suggesting that NA antibodies can interfere with virus attachment. Inhibition of both processes, virus release and virus binding, may explain why NA antibodies efficiently blocked virus dissemination in vitro and in vivo. Anti-NA immune sera showed broader reactivity than anti-HA sera in hemagglutination inhibition tests and demonstrated cross-subtype activity in sialidase inhibition tests. These remarkable features of NA antibodies highlight the importance of the NA antigen for the development of next-generation influenza virus vaccines.