Department of Biological Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America.
Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia.
PeerJ. 2022 Jun 10;10:e13559. doi: 10.7717/peerj.13559. eCollection 2022.
Bacterial communities in and on wild hosts are increasingly appreciated for their importance in host health. Through both direct and indirect interactions, bacteria lining vertebrate gut mucosa provide hosts protection against infectious pathogens, sometimes even in distal body regions through immune regulation. In house finches (), the bacterial pathogen (MG) causes conjunctivitis, with ocular inflammation mediated by pro- and anti-inflammatory cytokines and infection triggering MG-specific antibodies. Here, we tested the role of gut bacteria in host responses to MG by using oral antibiotics to perturb bacteria in the gut of captive house finches prior to experimental inoculation with MG. We found no clear support for an impact of gut bacterial disruption on conjunctival pathology, MG load, or plasma antibody levels. However, there was a non-significant trend for birds with intact gut communities to have greater conjunctival pathology, suggesting a possible impact of gut bacteria on pro-inflammatory cytokine stimulation. Using 16S bacterial rRNA amplicon sequencing, we found dramatic differences in cloacal bacterial community composition between captive, wild-caught house finches in our experiment and free-living finches from the same population, with lower bacterial richness and core communities composed of fewer genera in captive finches. We hypothesize that captivity may have affected the strength of results in this experiment, necessitating further study with this consideration. The abundance of anthropogenic impacts on wildlife and their bacterial communities, alongside the emergence and spread of infectious diseases, highlights the importance of studies addressing the role of commensal bacteria in health and disease, and the consequences of gut bacterial shifts on wild hosts.
野生宿主体内和体表的细菌群落，其在宿主健康方面的重要性正日益受到重视。通过直接和间接的相互作用，脊椎动物肠道黏膜上的细菌为宿主提供了抵御传染性病原体的保护，甚至有时通过免疫调节在远离身体的部位提供保护。在家雀（）中，细菌病原体（MG）会引起结膜炎，眼部炎症是由促炎和抗炎细胞因子以及感染触发的 MG 特异性抗体介导的。在这里，我们通过在实验接种 MG 之前使用口服抗生素来扰乱圈养家雀肠道中的细菌，从而测试了肠道细菌在家雀对 MG 的反应中的作用。我们没有发现肠道细菌破坏对结膜病理、MG 载量或血浆抗体水平有明显影响的确切证据。然而，肠道群落完整的鸟类结膜病理更严重的趋势表明，肠道细菌可能对促炎细胞因子刺激有影响。使用 16S 细菌 rRNA 扩增子测序，我们发现实验中圈养和野生捕获的家雀以及来自同一群体的自由生活的雀之间的泄殖腔细菌群落组成存在显著差异，圈养雀的细菌丰富度较低，核心群落由较少的属组成。我们假设圈养可能影响了本实验的结果强度，因此需要进一步研究并考虑这一因素。野生动物及其细菌群落受到的人为影响以及传染病的出现和传播，突显了研究共生细菌在健康和疾病中的作用以及肠道细菌变化对野生宿主的影响的重要性。
