Turkey respiratory and gut microbiota play important roles in promoting health and production performance. Loss of microbiota homeostasis due to pathogen infection can worsen the disease or predispose the bird to infection by other pathogens. While turkeys are highly susceptible to influenza viruses of different origins, the impact of influenza virus infection on turkey gut and respiratory microbiota has not been demonstrated. In this study, we investigated the relationships between low pathogenicity avian influenza (LPAI) virus replication, cytokine gene expression, and respiratory and gut microbiota disruption in specific-pathogen-free turkeys. Differential replication of two LPAI H5N2 viruses paralleled the levels of clinical signs and cytokine gene expression. During active virus shedding, there was significant increase of ileal and nasal bacterial contents, which inversely corresponded with bacterial species diversity. Spearman’s correlation tests between bacterial abundance and local viral titers revealed that LPAI virus-induced dysbiosis was strongest in the nasal cavity followed by trachea, and weakest in the gut. Significant correlations were also observed between cytokine gene expression levels and relative abundances of several bacteria in tracheas of infected turkeys. For example, interferon γ/λ and interleukin-6 gene expression levels were correlated positively with Staphylococcus and Pseudomonas abundances, and negatively with Lactobacillus abundance. Overall, our data suggest a potential relationship where bacterial community diversity and enrichment or depletion of several bacterial genera in the gut and respiratory tract are dependent on the level of LPAI virus replication. Further work is needed to establish whether respiratory and enteric dysbiosis in LPAI virus-infected turkeys is a result of host immunological responses or other causes such as changes in nutritional uptake.

中文翻译：

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火鸡甲型流感病毒感染诱导与细胞因子基因表达相关的呼吸道和肠道细菌失调

土耳其呼吸道和肠道微生物群在促进健康和生产性能方面发挥着重要作用。病原体感染导致的微生物群稳态丧失会使疾病恶化或使鸡更容易受到其他病原体的感染。虽然火鸡对不同来源的流感病毒高度敏感，但流感病毒感染对火鸡肠道和呼吸道微生物群的影响尚未得到证实。在这项研究中，我们研究了低致病性禽流感 (LPAI) 病毒复制、细胞因子基因表达以及无特定病原体火鸡的呼吸道和肠道微生物群破坏之间的关系。两种 LPAI H5N2 病毒的差异复制与临床症状和细胞因子基因表达水平平行。在活跃的病毒脱落期间，回肠和鼻腔细菌含量显着增加，这与细菌物种多样性成反比。Spearman 的细菌丰度和局部病毒滴度之间的相关性测试表明，LPAI 病毒引起的生态失调在鼻腔中最强，其次是气管，在肠道中最弱。还观察到细胞因子基因表达水平与受感染火鸡气管中几种细菌的相对丰度之间存在显着相关性。例如，干扰素 γ/λ 和白细胞介素 6 基因表达水平与葡萄球菌和假单胞菌丰度呈正相关，与乳酸杆菌丰度呈负相关。全面的，我们的数据表明一种潜在的关系，其中细菌群落多样性以及肠道和呼吸道中几种细菌属的富集或消耗取决于 LPAI 病毒复制的水平。需要进一步的工作来确定感染 LPAI 病毒的火鸡的呼吸道和肠道菌群失调是否是宿主免疫反应或其他原因（例如营养摄取变化）的结果。