Petruzzi Briana, Dickerman Allan, Lahmers Kevin, Scarratt William K, Inzana Thomas J
Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States.
Biocomplexity Institute and Initiative, University of Virginia, Virginia Tech, Charlottesville, VA, United States.
Front Microbiol. 2020 Jul 10;11:1561. doi: 10.3389/fmicb.2020.01561. eCollection 2020.
and are two of multiple agents responsible for bovine respiratory disease (BRD) in cattle. Following respiratory infection of calves with , may also be isolated from the lower respiratory tract. Because may form a biofilm during BRD, we sought to determine if can co-exist with in a polymicrobial biofilm and . Interactions between the two species in the biofilm were characterized and quantified by fluorescence hybridization (FISH). The biofilm matrix of each species was examined using fluorescently tagged lectins (FTL) specific for the exopolysaccharide (EPS) using confocal laser scanning microscopy. Bacterial interactions were determined by auto-aggregation and biofilm morphology. and were evenly distributed in the biofilm, and both species contributed to the polymicrobial biofilm matrix. The average biomass and biofilm thickness, and the total carbohydrate and protein content of the biofilm, were greatest when both species were present. Polymicrobial bacterial suspensions auto-aggregated faster than single species suspensions, suggesting physical interactions between the two species. Almost 300 genes were significantly differentially regulated when the bacteria were in a polymicrobial biofilm compared to a mono-species biofilm, as determined by RNA-sequencing. As expected, host genes associated with inflammation and immune response were significantly upregulated at the infection site following challenge. Encapsulated isolates not capable of forming a substantial biofilm enhanced an polymicrobial biofilm with , indicating they contributed to the polymicrobial biofilm matrix. Indirect evidence indicated that encapsulated also contributed to a polymicrobial biofilm . Only the EPS of could be detected by FTL staining of bovine tissues following challenge with . However, both species were isolated and an immune response to the biofilm matrix of both species was greater than the response to planktonic cells, suggesting encapsulated may take advantage of the biofilm to persist in the host during chronic BRD. These results may have important implications for the management and prevention of BRD.
[具体细菌名称1]和[具体细菌名称2]是导致牛呼吸道疾病（BRD）的多种病原体中的两种。在用[具体细菌名称1]感染犊牛呼吸道后，[具体细菌名称2]也可能从下呼吸道分离出来。由于[具体细菌名称2]在BRD期间可能形成生物膜，我们试图确定[具体细菌名称2]是否能与[具体细菌名称1]在多微生物生物膜[具体生物膜名称]中共存。通过荧光原位杂交（FISH）对生物膜中这两种细菌之间的相互作用进行了表征和定量。使用针对胞外多糖（EPS）的荧光标记凝集素（FTL），通过共聚焦激光扫描显微镜检查了每种细菌的生物膜基质。通过自动聚集和生物膜形态来确定细菌间的相互作用。[具体细菌名称1]和[具体细菌名称2]在[具体生物膜名称]生物膜中均匀分布，且两种细菌都对多微生物生物膜基质有贡献。当两种细菌都存在时，生物膜的平均生物量和厚度以及生物膜的总碳水化合物和蛋白质含量最大。多微生物细菌悬液比单种细菌悬液自动聚集得更快，表明这两种细菌之间存在物理相互作用。通过RNA测序确定，与单种生物膜相比，当细菌处于多微生物生物膜中时，近300个[具体细菌名称1]基因有显著差异表达。正如预期的那样，在用[具体细菌名称1]攻击后，感染部位与炎症和免疫反应相关的宿主基因显著上调。不能形成大量生物膜的包膜[具体细菌名称2]分离株增强了[具体细菌名称1]的多微生物生物膜，表明它们对多微生物生物膜基质有贡献。间接证据表明，包膜[具体细菌名称2]也对多微生物生物膜[具体生物膜名称]有贡献。在用[具体细菌名称1]攻击牛组织后，通过FTL染色仅能检测到[具体细菌名称1]的EPS。然而，两种细菌都被分离出来，并且对两种细菌生物膜基质的免疫反应大于对浮游细胞的反应，这表明包膜[具体细菌名称2]可能利用[具体细菌名称1]生物膜在慢性BRD期间在宿主体内持续存在。这些结果可能对BRD的管理和预防具有重要意义。
