H9N2 Influenza Virus Infections in Human Cells Require a Balance between Neuraminidase Sialidase Activity and Hemagglutinin Receptor Affinity
H9N2 Influenza Virus Infections in Human Cells Require a Balance between Neuraminidase Sialidase Activity and Hemagglutinin Receptor Affinity
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DOI：
10.1128/jvi.01210-20
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发表时间：
2020-09-01
影响因子：
5.4
通讯作者：
Watanabe, Yohei
中科院分区：
文献类型：
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作者：
Arai, Yasuha;Elgendy, Emad Mohamed;Watanabe, Yohei
一些禽流感（AI）病毒在其神经氨酸酶（NA）茎中具有多达20至30个氨基酸的缺失。这与病毒复制和宿主范围的变化有关。目前流行的H9 N2禽流感病毒只有一个2或3个氨基酸的缺失，这种缺失分别在G1和Y280谱系病毒中检测到。NA缺失对H9 N2表型的影响尚未完全阐明。在这项研究中，我们分离出G1突变体进行了8个氨基酸的缺失，在他们的NA柄。为了系统地分析NA茎长度和伴随的（去）糖基化对G1复制和宿主范围的影响，我们产生了具有各种NA茎长度并且糖基化或非糖基化的G1病毒。茎长度与NA唾液酸酶活性相关，使用低分子量底物，并与红细胞的病毒洗脱效力相关。G1病毒在禽类细胞和鸡蛋中的复制与NA茎长度呈正相关，但在人细胞和小鼠中呈负相关。NA茎长度调节G1病毒进入宿主细胞，较短的茎使G1更有效地进入人类细胞。然而，使用具有较高α 2，6-连接的唾液酸聚糖亲和力的血凝素（HA），NA茎长度对G1病毒感染的影响被逆转，较短的NA茎减少病毒进入人细胞。这些结果表明，HA结合亲和力和NA唾液酸酶活性之间的平衡，由NA茎长度调节，是G1病毒最佳进入人类气道细胞所必需的。重要信息H9 N2禽流感病毒是最流行的禽流感病毒之一，已引起家禽和人类的反复感染，构成巨大的公共卫生风险。H9 N2病毒已分化成多个谱系，其中G1谱系在全世界范围内最为流行。在这项研究中，我们分离的G1变异携带8个氨基酸的缺失在其NA茎，这是，据我们所知，在该领域中发现的H9 N2病毒中最长的缺失。NA茎长度被发现调节G1病毒进入宿主细胞，其作用是物种特异性的并且依赖于相应的HA结合亲和力。我们的研究结果表明，在自然界中，H9 N2 G1病毒的HA和NA的功能平衡的NA茎长度，导致可能的关联的宿主范围和毒性在家禽和哺乳动物在G1谱系病毒的进化。
Some avian influenza (AI) viruses have a deletion of up to 20 to 30 amino acids in their neuraminidase (NA) stalk. This has been associated with changes in virus replication and host range. Currently prevalent H9N2 AI viruses have only a 2or 3-amino-acid deletion, and such deletions were detected in G1 and Y280 lineage viruses, respectively. The effect of an NA deletion on the H9N2 phenotype has not been fully elucidated. In this study, we isolated G1 mutants that carried an 8-amino-acid deletion in their NA stalk. To systematically analyze the effect of NA stalk length and concomitant (de)glycosylation on G1 replication and host range, we generated G1 viruses that had various NA stalk lengths and that were either glycosylated or not glycosylated. The stalk length was correlated with NA sialidase activity, using low-molecular-weight substrates, and with virus elution efficacy from erythrocytes. G1 virus replication in avian cells and eggs was positively correlated with the NA stalk length but was negatively correlated in human cells and mice. NA stalk length modulated G1 virus entry into host cells, with shorter stalks enabling more efficient G1 entry into human cells. However, with a hemagglutinin (HA) with a higher a2,6-linked sialylglycan affinity, the effect of NA stalk length on G1 virus infection was reversed, with shorter NA stalks reducing virus entry into human cells. These results indicate that a balance between HA binding affinity and NA sialidase activity, modulated by NA stalk length, is required for optimal G1 virus entry into human airway cells.IMPORTANCE H9N2 avian influenza (AI) virus, one of the most prevalent AI viruses, has caused repeated poultry and human infections, posing a huge public health risk. The H9N2 virus has diversified into multiple lineages, with the G1 lineage being the most prevalent worldwide. In this study, we isolated G1 variants carrying an 8-amino-acid deletion in their NA stalk, which is, to our knowledge, the longest deletion found in H9N2 viruses in the field. The NA stalk length was found to modulate G1 virus entry into host cells, with the effects being species specific and dependent on the corresponding HA binding affinity. Our results suggest that, in nature, H9N2 G1 viruses balance their HA and NA functions by the NA stalk length, leading to the possible association of host range and virulence in poultry and mammals during the evolution of G1 lineage viruses.