Department of Microbiology, College of Veterinary Medicine, University of Al-Qadisiyah, Al-Diwaniyah, Iraq.
Department of Public Health, College of Veterinary Medicine, University of Al-Qadisiyah, Al-Diwaniyah, Iraq.
Open Vet J. 2024 Jul;14(7):1644-1657. doi: 10.5455/OVJ.2024.v14.i7.14. Epub 2024 Jul 31.
Although milk is nutritionally valuable, it also serves as a significant medium for the transmission of pathogens and their toxins.
This study aimed to investigate the role of enterotoxin gene A (SEA) in the development of bovine mastitis. We accomplished this by examining milk through polymerase chain reaction (PCR) testing, amino acid substitution analysis, and phylogenetic analysis.
A total of fifty milk samples were collected from locally bred dairy cows in Al-Diwaniyah, located in southern Iraq. We employed the VITEK-2 platform to validate the diagnosis of and confirm the results of routine tests (culturing and biochemical tests). Subsequently, the genetic mutation and phylogeny analysis were achieved utilizing DNA sequencing to 16S rRNA and enterotoxin A genes.
66% (33/50) of the milk samples found to be contain by the VITEK-2 system. Furthermore, 25/33 of the samples were positive by the PCR test. While 60% (15 out of 25) tested positive for the SEA gene. After genomic analysis, we identified amino acid substitutions of serine, glutamine with arginine, tyrosine with cysteine, and aspartic acid with glycine at positions 9, 101, 119, 187, and 191. The phylogenetic investigation demonstrated a genetic relationship between our isolates (Iraqi isolates) and isolates from Indian and the United States.
Our study indicated the widespread distribution of the enterotoxin gene A (SEA) of among dairy cows. The molecular study revealed significant changes in key amino acids that could play an important role in the bacterium's pathogenesis. The phylogenetic similarities among samples from various countries suggest that the bacteria has spread globally.
尽管牛奶具有营养价值，但它也是病原体及其毒素传播的重要媒介。
本研究旨在探讨肠毒素基因 A（SEA）在奶牛乳腺炎发病机制中的作用。我们通过聚合酶链反应（PCR）检测、氨基酸取代分析和系统发育分析来检测牛奶来实现这一目标。
从伊拉克南部迪瓦尼亚省当地饲养的奶牛中采集了 50 份牛奶样本。我们采用 VITEK-2 平台验证了 和常规检测（培养和生化检测）结果的诊断。随后，通过 DNA 测序对 16S rRNA 和肠毒素 A 基因进行了遗传突变和系统发育分析。
VITEK-2 系统发现 66%（33/50）的牛奶样本 阳性。此外，PCR 检测有 25/33 例阳性。SEA 基因阳性率为 60%（15/25）。经过基因组分析，我们发现 9、101、119、187 和 191 位的丝氨酸、谷氨酸被精氨酸、酪氨酸被半胱氨酸、天冬氨酸被甘氨酸取代。系统发育分析表明，我们的分离株（伊拉克分离株）与来自印度和美国的分离株之间存在遗传关系。
本研究表明，肠毒素基因 A（SEA）在奶牛乳腺炎中广泛分布。分子研究表明，关键氨基酸发生了显著变化，这可能在细菌的发病机制中发挥重要作用。来自不同国家的 样本之间的系统发育相似性表明该细菌已在全球范围内传播。
