Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, USDA-ARS, Beltsville, MD, USA.
BMC Genomics. 2022 Jul 8;23(1):498. doi: 10.1186/s12864-022-08725-z.
The impact of S. enterica colonization in cattle is highly variable and often serovar-dependent. The aim of this study was to compare the global transcriptomes of highly pathogenic bovine-adapted S. enterica serovar Dublin and the less pathogenic, bovine-adapted, serovar Cerro during interactions with bovine epithelial cells, to identify genes that impact serovar-related outcomes of S. enterica infections in dairy animals.
Bovine epithelial cells were infected with S. enterica strains from serovars Dublin and Cerro, and the bacterial RNA was extracted and sequenced. The total number of paired-end reads uniquely mapped to non-rRNA and non-tRNA genes in the reference genomes ranged between 12.1 M (Million) and 23.4 M (median: 15.7 M). In total, 360 differentially expressed genes (DEGs) were identified with at least two-fold differences in the transcript abundances between S. Dublin and S. Cerro (false discovery rate ≤ 5%). The highest number of DEGs (17.5%, 63 of 360 genes) between the two serovars were located on the genomic regions potentially associated with Salmonella Pathogenicity Islands (SPIs). DEGs potentially located in the SPI-regions that were upregulated (≥ 2-fold) in the S. Dublin compared with S. Cerro included: 37 SPI-1 genes encoding mostly Type 3 Secretion System (T3SS) apparatus and effectors; all of the six SPI-4 genes encoding type I secretion apparatus (siiABCDEF); T3SS effectors and chaperone (sopB, pipB, and sigE) located in SPI-5; type VI secretion system associated protein coding genes (sciJKNOR) located in SPI-6; and T3SS effector sopF in SPI-11. Additional major functional categories of DEGs included transcription regulators (n = 25), amino acid transport and metabolism (n = 20), carbohydrate transport and metabolism (n = 20), energy production and metabolism (n = 19), cell membrane biogenesis (n = 18), and coenzyme transport and metabolism (n = 15). DEGs were further mapped to the metabolic pathways listed in the KEGG database; most genes of the fatty acid β-oxidation pathway were upregulated/uniquely present in the S. Dublin strains compared with the S. Cerro strains.
This study identified S. enterica genes that may be responsible for symptomatic or asymptomatic infection and colonization of two bovine-adapted serovars in cattle.
肠沙门氏菌在牛中的定植影响高度可变，通常依赖于血清型。本研究的目的是比较高致病性牛适应血清型都柏林沙门氏菌和低致病性牛适应血清型塞罗与牛上皮细胞相互作用时的全转录组，以确定影响沙门氏菌感染奶牛血清型相关结果的基因。
用来自血清型都柏林和塞罗的沙门氏菌菌株感染牛上皮细胞，提取并测序细菌 RNA。非 rRNA 和非 tRNA 基因在参考基因组中唯一映射的配对末端读数总数在 1210 万（百万）和 2340 万（中位数：1570 万）之间。总共鉴定出 360 个差异表达基因（DEGs），它们在 S. 都柏林和 S. 塞罗之间的转录丰度差异至少为两倍（错误发现率≤5%）。这两个血清型之间数量最多的 DEGs（17.5%，360 个基因中的 63 个）位于与沙门氏菌致病岛（SPI）相关的基因组区域。在 S. 都柏林与 S. 塞罗相比上调（≥2 倍）的潜在位于 SPI 区域的 DEGs 包括：37 个编码主要 III 型分泌系统（T3SS）装置和效应物的 SPI-1 基因；编码 I 型分泌装置（siiABCDEF）的所有 6 个 SPI-4 基因；位于 SPI-5 中的 T3SS 效应物和伴侣（sopB、pipB 和 sigE）；位于 SPI-6 中的与 VI 型分泌系统相关的蛋白编码基因（sciJKNOR）；以及位于 SPI-11 中的 T3SS 效应物 sopF。DEGs 的其他主要功能类别包括转录调节剂（n=25）、氨基酸转运和代谢（n=20）、碳水化合物转运和代谢（n=20）、能量产生和代谢（n=19）、细胞膜生物发生（n=18）和辅酶转运和代谢（n=15）。DEGs 进一步映射到 KEGG 数据库中列出的代谢途径；与 S. 塞罗菌株相比，脂肪酸β-氧化途径的大多数基因在 S. 都柏林菌株中上调/独特存在。
本研究鉴定了肠沙门氏菌基因，这些基因可能与两种牛适应血清型在牛中的症状性或无症状感染和定植有关。
