Viruses are often cultured in cell lines for research and vaccine development, and those often differ from the natural hosts or tissues. Cell lines can also differ in the presence of virus receptors, such as the sialic acid (Sia) receptors used by influenza A viruses (IAV), which can vary in linkage (α2,3- or α2,6-linkage) and form (N-glycolylneuraminic acid [Neu5Gc] or N-acetylneuraminic acid [Neu5Ac]). The selective pressures resulting from passaging viruses in cell types with host-specific variations in viral receptors are still only partially understood. IAV are commonly cultured in MDCK cells which are both derived from canine kidney tubule epithelium and inherently heterogeneous. MDCK cells naturally present Neu5Ac and α2,3-linked Sia forms. Here, we examine natural MDCK variant lineages, as well as engineered variants that synthesize Neu5Gc and/or α2,6-linkages. We determined how viral genetic variation occurred within human H3N2, H1N1 pandemic and canine H3N2 IAV populations when serially passaged in MDCK cell lines that vary in cell type (MDCK-Type I or MDCK-Type II clones) and in Sia display. Deep sequencing of viral genomes showed small numbers of consensus-level mutations, mostly within the hemagglutinin (HA) gene. Both human IAV showed variants in the HA stem and the HA receptor-binding site of populations passaged in cells displaying Neu5Gc. Canine H3N2 showed variants near the receptor-binding site when passaged in cells displaying Neu5Gc or α2,6-linkages. Viruses replicated to low titres in MDCK-Type II cells, suggesting that not all cell types in heterogeneous MDCK cell populations are equally permissive to infection.

中文翻译：

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在不同 MDCK 细胞系（包括表达不同唾液酸受体的细胞系）中生长的三种甲型流感病毒株的序列动力学。

病毒通常在细胞系中培养用于研究和疫苗开发，这些病毒通常与天然宿主或组织不同。细胞系也可能因病毒受体的存在而不同，例如甲型流感病毒 (IAV) 使用的唾液酸 (Sia) 受体，其连接方式（α2,3- 或 α2,6- 连接）和形式（ N-羟乙酰神经氨酸 [Neu5Gc] 或 N-乙酰神经氨酸 [Neu5Ac]）。在病毒受体中具有宿主特异性变异的细胞类型中传代病毒所产生的选择压力仍然只是部分了解。IAV 通常在 MDCK 细胞中培养，MDCK 细胞既来源于犬肾小管上皮，又具有固有的异质性。MDCK 细胞自然呈现 Neu5Ac 和 α2,3 连接的 Sia 形式。在这里，我们检查自然 MDCK 变异谱系，以及合成 Neu5Gc 和/或 α2,6-连接的工程变体。我们确定了在不同细胞类型（MDCK-I 型或 MDCK-II 型克隆）和 Sia 展示的 MDCK 细胞系中连续传代时，病毒遗传变异如何在人类 H3N2、H1N1 大流行和犬 H3N2 IAV 群体中发生。病毒基因组的深度测序显示少量共有水平的突变，主要在血凝素 (HA) 基因内。两种人类 IAV 都显示出在显示 Neu5Gc 的细胞中传代的群体的 HA 干和 HA 受体结合位点的变异。当在显示 Neu5Gc 或 α2,6-连接的细胞中传代时，犬 H3N2 在受体结合位点附近显示出变异。病毒在 MDCK-II 型细胞中复制到低滴度，表明并非异质 MDCK 细胞群中的所有细胞类型都同样容易感染。