Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Südufer 10, 17493 Greifswald - Insel Riems, Germany.
Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, 17493 Greifswald - Insel Riems, Germany.
Vet Microbiol. 2019 Apr;231:160-168. doi: 10.1016/j.vetmic.2019.03.013. Epub 2019 Mar 12.
Influenza A viruses (IAV) have caused seasonal epidemics and severe pandemics in humans. Novel pandemic strains as in 2009 may emerge from pigs, serving as perpetual virus reservoir. However, reliably effective vaccination has remained a key issue for humans and swine. Here, we generated a novel double-attenuated influenza live vaccine by reverse genetics and subjected immunized mice and pigs to infection with the homologous wild-type, another homosubtypic H1N1, or a heterosubtypic H3N2 virus to address realistic challenge constellations. This attenuated mutant contains an artificial, strictly elastase-dependent hemagglutinin cleavage site and a C-terminally truncated NS1 protein from the IAV A/Bayern/74/2009 (H1N1). Prior to challenge, we immunized mice once and pigs twice intranasally. In vitro, the double-attenuated mutant replicated strictly elastase-dependently. Immunized mice and pigs developed neither clinical symptoms nor detectable virus replication after homologous challenge. In pigs, we observed considerably reduced clinical signs and no nasal virus shedding after homosubtypic and reduced viral loads in respiratory tracts after heterosubtypic infection. Protection against homosubtypic challenge suggests that an optimized backbone strain may require less frequent updates with recent HA and NA genes and still induce robust protection in relevant IAV hosts against drifted viruses.
甲型流感病毒（IAV）已在人类中引发季节性流行和严重的大流行。2009 年出现的新型大流行株可能源自猪，成为永久的病毒储存库。然而，可靠有效的疫苗接种一直是人类和猪的关键问题。在这里，我们通过反向遗传学生成了一种新型的双减毒流感活疫苗，并对免疫的小鼠和猪进行了同源野生型、另一种同亚型 H1N1 或异亚型 H3N2 病毒的感染，以应对现实的挑战组合。这种减毒突变体包含一个人工的、严格依赖弹性蛋白酶的血凝素裂解位点和来自 IAV A/Bayern/74/2009（H1N1）的截短的 NS1 蛋白。在挑战之前，我们对小鼠进行了一次鼻内免疫，对猪进行了两次鼻内免疫。在体外，双减毒突变体严格依赖弹性蛋白酶复制。同源性挑战后，免疫的小鼠和猪既没有出现临床症状，也没有检测到病毒复制。在猪中，我们观察到同亚型感染后的临床症状明显减轻，没有鼻病毒排出，异亚型感染后的呼吸道病毒载量也降低。对同亚型挑战的保护表明，优化的骨架株可能需要较少的最近 HA 和 NA 基因更新，并且仍然可以在相关的 IAV 宿主中诱导对漂移病毒的强大保护。
