Unit for Environmental Sciences and Management, Microbiology, North-West University, Potchefstroom, South Africa.
Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa; International Centre for Antimicrobial Resistance Solutions, Copenhagen S, 2300, Denmark; Antimicrobial Research Unit, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Infect Genet Evol. 2024 Sep;123:105649. doi: 10.1016/j.meegid.2024.105649. Epub 2024 Jul 25.
Priestia is a genus that was renamed from the genus Bacillus based on the conserved signature indels (CSIs) in protein sequences that separate Priestia species from Bacillus, with the latter only including species closely related to B. subtilis and B. cereus. Diagnosis of anthrax, a zoonotic disease, is implicated by tripartite anthrax virulence genes (lef, pagA, and cya) and poly-γ-D-glutamic acid capsular genes cap-ABCDE of Bacillus anthracis. Due to the amplification of anthrax virulence genes in Priestia isolates, the search for homologous anthrax virulence genes within the Priestia genomes (n = 9) isolated from animal blood smears was embarked upon through whole genome sequencing. In silico taxonomic identification of the isolates was conducted using genome taxonomy database (GTDB), average nucleotide identity (ANI), and multi-locus sequence typing (MLST), which identified the genomes as P. aryabhattai (n = 5), P. endophytica (n = 2) and P. megaterium (n = 2). A pan-genome analysis was further conducted on the Priestia genomes, including the screening of virulence, antibiotic resistance genes and mobile genetic elements on the sequenced genomes. The oligoribonuclease NrnB protein sequences showed that Priestia spp. possess a unique CSI that is absent in other Bacillus species. Furthermore, the CSI in P. endophytica is unique from other Priestia spp. Pan-genomic analysis indicates that P. endophytica clusters separately from P. aryabhattai and P. megaterium. In silico BLASTn genome analysis using the SYBR primers, Taqman probes and primers that target the chromosomal marker (Ba-1), protective antigen (pagA), and lethal factor (lef) on B. anthracis, showed partial binding to Priestia regions encoding for hypothetical proteins, pyridoxine biosynthesis, hydrolase, and inhibitory proteins. The antibiotic resistance genes (ARG) profile of Priestia spp. showed that the genomes contained no more than two ARGs. This included genes conferring resistance to rifamycin and fosfomycin on P. endophytica, as well as clindamycin on P. aryabhattai and P. megaterium. Priestia genomes lacked B. anthracis plasmids and consisted of plasmid replicon types with unknown functions. Furthermore, the amplification of Priestia strains may result in false positives when qPCR is used to detect the virulence genes of B. anthracis in soil, blood smears, and/or environmental samples.
普雷蒂亚是一个基于蛋白质序列中保守特征缺失（CSIs）的属，该特征将普雷蒂亚物种与芽孢杆菌属区分开来，后者仅包括与枯草芽孢杆菌和蜡状芽孢杆菌密切相关的物种。炭疽病是一种人畜共患疾病，炭疽三价毒力基因（lef、pagA 和 cya）和多聚γ-D-谷氨酸荚膜基因 cap-ABCDE 的存在暗示了炭疽的诊断。由于在普雷蒂亚分离株中扩增了炭疽毒力基因，因此通过全基因组测序开始在从动物血涂片分离的普雷蒂亚基因组（n=9）中寻找同源炭疽毒力基因。通过基因组分类数据库（GTDB）、平均核苷酸同一性（ANI）和多位点序列分型（MLST）对分离株进行了分类学鉴定，结果表明这些基因组为 P. aryabhattai（n=5）、P. endophytica（n=2）和 P. megaterium（n=2）。进一步对普雷蒂亚基因组进行了泛基因组分析，包括对测序基因组上的毒力、抗生素耐药基因和移动遗传元件进行了筛选。寡核糖核酸酶 NrnB 蛋白序列表明，普雷蒂亚属具有独特的 CSI，而其他芽孢杆菌属中不存在该 CSI。此外，P. endophytica 的 CSI 与其他普雷蒂亚属不同。泛基因组分析表明，P. endophytica 与 P. aryabhattai 和 P. megaterium 分别聚类。使用 SYBR 引物、Taqman 探针和针对 B. anthracis 染色体标记（Ba-1）、保护性抗原（pagA）和致死因子（lef）的引物进行的 SYBR 基因组分析表明，与编码假设蛋白、吡啶素生物合成、水解酶和抑制蛋白的普雷蒂亚区域有部分结合。普雷蒂亚属的抗生素耐药基因（ARG）图谱表明，基因组中不超过两个 ARG。这包括 P. endophytica 对 rifamycin 和 fosfomycin 的耐药基因，以及 P. aryabhattai 和 P. megaterium 对 clindamycin 的耐药基因。普雷蒂亚基因组缺乏炭疽芽孢杆菌质粒，由未知功能的质粒复制子类型组成。此外，当使用 qPCR 检测土壤、血涂片和/或环境样本中的炭疽毒力基因时，普雷蒂亚菌株的扩增可能会导致假阳性。
