Institute of Virology, University Medical Center Freiburg, Freiburg, Germany.
Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Microbiol Spectr. 2022 Dec 21;10(6):e0142422. doi: 10.1128/spectrum.01424-22. Epub 2022 Nov 29.
Recurring epizootic influenza A virus (IAV) infections in domestic livestock such as swine and poultry are associated with a substantial economic burden and pose a constant threat to human health. Therefore, universally applicable and safe animal vaccines are urgently needed. We recently demonstrated that a reassortment-incompatible chimeric bat H17N10 virus harboring the A/swan/Germany/R65/2006 (H5N1) surface glycoproteins hemagglutinin (HA) and neuraminidase (NA) can be efficiently used as a modified live influenza vaccine (MLIV). To ensure vaccine safety and, thus, improve the applicability of this novel MLIV for mammalian usage, we performed consecutive passaging in eggs and chickens. Following passaging, we identified mutations in the viral polymerase subunits PB2 (I382S), PB1 (Q694H and I695K), and PA (E141K). Strikingly, recombinant chimeric viruses encoding these mutations showed no growth deficiencies in avian cells but displayed impaired growth in human cells and mice. Homologous prime-boost immunization of mice with one of these avian-adapted chimeric viruses, designated rR65/H17N10, elicited a strong neutralizing antibody response and conferred full protection against lethal highly pathogenic avian influenza virus (HPAIV) H5N1 challenge infection. Importantly, the insertion of the avian-adaptive mutations into the conventional avian-like A/SC35M/1980 (H7N7) and prototypic human A/PR/8/34 (H1N1) viruses led to attenuated viral growth in human cells and mice. Collectively, our data show that the polymerase mutations identified here can be utilized to further improve the safety of our novel H17N10-based MLIV candidates for future mammalian applications. Recurring influenza A virus outbreaks in livestock, particularly in swine and chickens, pose a constant threat to humans. Live attenuated influenza vaccines (LAIVs) might be a potent tool to prevent epizootic outbreaks and the resulting human IAV infections; however, LAIVs have several disadvantages, especially in terms of reassortment with circulating IAVs. Notably, the newly identified bat influenza A viruses H17N10 and H18N11 cannot reassort with conventional IAVs. Chimeric bat influenza A viruses encoding surface glycoproteins of conventional IAV subtypes might thus function as safe and applicable modified live influenza vaccines (MLIVs).
在猪和家禽等家畜中反复发生的流行性流感病毒 (IAV) 感染与巨大的经济负担有关，并对人类健康构成持续威胁。因此，迫切需要普遍适用和安全的动物疫苗。我们最近证明，一种带有 A/swan/Germany/R65/2006（H5N1）表面糖蛋白血凝素 (HA) 和神经氨酸酶 (NA) 的重组不兼容嵌合蝙蝠 H17N10 病毒可作为改良活流感疫苗 (MLIV) 有效使用。为了确保疫苗的安全性，从而提高这种新型 MLIV 对哺乳动物使用的适用性，我们在鸡蛋和鸡中进行了连续传代。传代后，我们在病毒聚合酶亚基 PB2（I382S）、PB1（Q694H 和 I695K）和 PA（E141K）中发现了突变。引人注目的是，编码这些突变的重组嵌合病毒在禽细胞中没有表现出生长缺陷，但在人细胞和小鼠中显示出生长受损。用其中一种适应性强的嵌合病毒，即 rR65/H17N10，对小鼠进行同源初免-加强免疫，可引起强烈的中和抗体反应，并完全保护免受致死性高致病性禽流感病毒 (HPAIV) H5N1 挑战感染。重要的是，将这些适应性强的鸟类突变插入常规的禽样 A/SC35M/1980（H7N7）和原型人 A/PR/8/34（H1N1）病毒中，导致在人细胞和小鼠中病毒生长减弱。总之，我们的数据表明，这里鉴定的聚合酶突变可用于进一步提高我们新型基于 H17N10 的 MLIV 候选物在未来哺乳动物应用中的安全性。在猪和鸡等家畜中反复发生的流感病毒爆发对人类构成持续威胁。活减毒流感疫苗（LAIV）可能是预防流行病爆发和由此导致的人类 IAV 感染的有效工具；然而，LAIV 有几个缺点，尤其是在与循环 IAV 重组方面。值得注意的是，新发现的蝙蝠流感病毒 H17N10 和 H18N11 不能与常规 IAV 重组。编码常规 IAV 亚型表面糖蛋白的嵌合蝙蝠流感病毒可能作为安全适用的改良活流感疫苗（MLIV）发挥作用。
