Saunderson Sarah C, Nouioui Imen, Midwinter Anne C, Wilkinson David A, Young Melanie J, McInnes Kate M, Watts Jim, Sangal Vartul
Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany.
mSystems. 2021 Jun 29;6(3):e0032021. doi: 10.1128/mSystems.00320-21. Epub 2021 Jun 8.
Yellow-eyed penguins, Megadyptes antipodes, are an endangered species that are endemic to New Zealand. Outbreaks of diphtheritic stomatitis have caused significant mortality for this species, especially among young chicks. In this study, we isolated 16 sp. isolates from the oral cavities of 2- to 14-day-old chicks at a range of infection stages and sequenced the genomes to understand their virulence mechanisms. Phylogenomic and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) characterization indicate that these strains belong to a novel species. A simple multiplex PCR-based diagnostic assay has been developed to identify these strains rapidly and reliably. Similar to other corynebacteria, genomic islands and prophages introduced significant diversity among these strains that has potentially led to minor functional variations between the two lineages. Despite the presence of multiple corynebacterial virulence genes and a -type pilus gene cluster among these strains, the survival rate was much higher in Galleria mellonella larvae than in those inoculated with Corynebacterium ulcerans NZRM 818 and Corynebacterium pseudotuberculosis NZRM 3004. Therefore, these strains are opportunistic pathogens causing high mortality among young penguin chicks due to a less-developed immune system. Yellow-eyed penguins, Megadyptes antipodes, are endangered species with a sharp decline in the numbers of breeding pairs over the last 2 decades. Diphtheritic stomatitis, characterized by a thick fibrinopurulent exudate in the oral cavities and symptoms, including inanition and significant weight loss, is responsible for significant mortality among the young chicks. These chicks are treated with antibiotics, amoxicillin-clavulanic acid or enrofloxacin, but do not always recover from the infection. The pathogen causing these infections and the mechanism of pathogenesis are unclear. This study has identified a novel species to be associated with diphtheritic stomatitis in yellow-eyed penguins with potential virulence genes that are likely involved in pathogenesis. Importantly, a gene encoding an exotoxin, phospholipase D, is present among these strains. The inactivated form of this enzyme could potentially be used as an effective vaccine to protect these penguins from infection.
黄眼企鹅（Megadyptes antipodes）是新西兰特有的濒危物种。白喉性口炎的爆发已导致该物种大量死亡，尤其是幼雏。在本研究中，我们从处于不同感染阶段的2至14日龄雏鸟口腔中分离出16株菌株，并对其基因组进行测序以了解其致病机制。系统发育基因组学和基质辅助激光解吸电离飞行时间（MALDI - TOF）鉴定表明这些菌株属于一个新物种。已开发出一种基于多重PCR的简单诊断方法，用于快速、可靠地鉴定这些菌株。与其他棒状杆菌类似，基因组岛和原噬菌体在这些菌株中引入了显著的多样性，这可能导致两个谱系之间存在微小功能差异。尽管这些菌株中存在多个棒状杆菌毒力基因和一个α型菌毛基因簇，但在大蜡螟幼虫中的存活率远高于接种溃疡棒状杆菌NZRM 818和伪结核棒状杆菌NZRM 3004的幼虫。因此，这些菌株是机会致病菌，由于幼企鹅免疫系统发育不完善，导致幼雏大量死亡。黄眼企鹅（Megadyptes antipodes）是濒危物种，在过去20年中繁殖对数量急剧下降。白喉性口炎的特征是口腔中有浓稠的纤维蛋白脓性渗出物，症状包括虚弱和体重显著减轻，是幼雏大量死亡的原因。这些雏鸟用抗生素、阿莫西林 - 克拉维酸或恩诺沙星治疗，但并不总是能从感染中康复。引起这些感染的病原体和致病机制尚不清楚。本研究已鉴定出一种与黄眼企鹅白喉性口炎相关的新物种，其具有可能参与致病过程的潜在毒力基因。重要的是，这些菌株中存在一种编码外毒素磷脂酶D的基因。这种酶的灭活形式可能潜在地用作一种有效疫苗，以保护这些企鹅免受感染。
