Table_5_Time-resolved characterization of the innate immune response in the respiratory epithelium of human, porcine, and bovine during influenza virus infection.xlsx

Viral cross-species transmission is recognized to be a major threat to both human and animal health, however detailed information on determinants underlying virus host tropism and susceptibility is missing. Influenza C and D viruses (ICV, IDV) are two respiratory viruses that share up to 50% genetic similarity, and both employ 9-O-acetylated sialic acids to enter a host cell. While ICV infections are mainly restricted to humans, IDV possesses a much broader host tropism and has shown to have a zoonotic potential. This suggests that additional virus–host interactions play an important role in the distinct host spectrum of ICV and IDV. In this study, we aimed to characterize the innate immune response of the respiratory epithelium of biologically relevant host species during influenza virus infection to identify possible determinants involved in viral cross-species transmission. To this end, we performed a detailed characterization of ICV and IDV infection in primary airway epithelial cell (AEC) cultures from human, porcine, and bovine origin. We monitored virus replication kinetics, cellular and host tropism, as well as the host transcriptional response over time at distinct ambient temperatures. We observed that both ICV and IDV predominantly infect ciliated cells, independently from host and temperature. Interestingly, temperature had a profound influence on ICV replication in both porcine and bovine AEC cultures, while IDV replicated efficiently irrespective of temperature and host. Detailed time-resolved transcriptome analysis revealed both species-specific and species uniform host responses and highlighted 34 innate immune-related genes with clear virus-specific and temperature-dependent profiles. These data provide the first comprehensive insights into important common and species-specific virus-host dynamics underlying the distinct host tropism of ICV and IDV, as well as possible determinants involved in viral cross-species transmission.

病毒跨物种传播（viral cross-species transmission）被认为是威胁人类与动物健康的重大隐患，但目前仍缺乏关于病毒宿主嗜性（host tropism）与易感性潜在决定因素的详尽信息。丙型、丁型流感病毒（Influenza C and D viruses, ICV, IDV）是两种呼吸道病毒，二者基因组同源性高达50%，且均利用9-O-乙酰化唾液酸（9-O-acetylated sialic acids）入侵宿主细胞。丙型流感病毒感染主要局限于人类，而丁型流感病毒则具有更广泛的宿主嗜性，并已被证实具备人畜共患潜力（zoonotic potential）。这表明额外的病毒-宿主互作（virus-host interactions）在丙型、丁型流感病毒迥异的宿主谱（host spectrum）中发挥关键作用。
本研究旨在解析流感病毒感染过程中，具有生物学相关性的宿主物种呼吸道上皮的固有免疫应答（innate immune response），以挖掘参与病毒跨物种传播的潜在决定因素。为此，我们针对源自人类、猪源与牛源的原代气道上皮细胞（Airway Epithelial Cell, AEC）培养体系，开展了丙型、丁型流感病毒感染的详细表征分析。我们监测了不同环境温度下，病毒复制动力学（virus replication kinetics）、细胞与宿主嗜性以及宿主随时间变化的转录组应答（transcriptional response）。
研究发现，丙型、丁型流感病毒均主要感染纤毛细胞，且该特性不受宿主物种与环境温度的影响。值得注意的是，环境温度对猪、牛原代气道上皮细胞培养体系中的丙型流感病毒复制具有显著影响，而丁型流感病毒的复制效率则不受温度与宿主物种的限制。时间分辨转录组分析（time-resolved transcriptome analysis）显示，宿主应答兼具物种特异性与物种一致性，并筛选出34个与固有免疫相关的基因，其表达模式呈现明确的病毒特异性与温度依赖性。
本研究数据首次全面揭示了丙型、丁型流感病毒迥异宿主嗜性背后关键的共通与物种特异性病毒-宿主互作机制，同时为病毒跨物种传播的潜在决定因素提供了重要线索。