Edinburgh Research Explorer Presence of DNA from Chlamydia-like organisms in the nasal cavities of grey seal pups (Halichoerus grypus) and three different substrates present in a breeding colony

Background: Chlamydia -like organisms (CLO) have been found to be present in many environmental niches, including human sewage and agricultural run-off, as well as in a number of aquatic species worldwide. Therefore, monitoring their presence in sentinel wildlife species may be useful in assessing the wider health of marine food webs in response to habitat loss, pollution and disease. We used nasal swabs from live ( n = 42) and dead ( n = 50) pre-weaned grey seal pups and samples of differing natal substrates ( n = 8) from an off-shore island devoid of livestock and permanent human habitation to determine if CLO DNA is present in these mammals and to identify possible sources. Results: We recovered CLO DNA from 32/92 (34.7%) nasal swabs from both live ( n = 17) and dead ( n = 15) seal pups that clustered most closely with currently recognised species belonging to three chlamydial families: Parachlamy-diaceae ( n = 22), Rhabdochlamydiaceae ( n = 6), and Simkaniaceae ( n = 3). All DNA positive sediment samples ( n = 7) clustered with the Rhabdochlamydiaceae . No difference was found in rates of recovery of CLO DNA in live versus dead pups suggesting the organisms are commensal but their potential as opportunistic secondary pathogens could not be determined. Conclusion: This is the first report of CLO DNA being found in marine mammals. This identification warrants further investigation in other seal populations around the coast of the UK and in other areas of the world to determine if this finding is unique or more common than shown by this data. Further investigation would also be warranted to determine if they are present as purely commensal organisms or whether they could also be opportunistic pathogens in seals, as well as to investigate possible sources of origin, including whether they originated as a result of anthropogenic impacts, including human waste and agricultural run-off.

背景：已发现衣原体样生物（CLO）存在于许多环境生态位中，包括人类污水和农业径流，以及世界上许多水生物种中。因此，监测它们在指示性野生动物物种中的存在情况，可能有助于评估海洋食物网在栖息地丧失、污染和疾病影响下的整体健康状况。我们使用了来自一个无家畜且无人长期居住的近海岛屿上的活的（n = 42）和死亡的（n = 50）断奶前灰海豹幼崽的鼻拭子以及不同出生基质的样本（n = 8），以确定这些哺乳动物中是否存在CLO DNA，并确定可能的来源。 结果：我们从活的（n = 17）和死亡的（n = 15）海豹幼崽的92个鼻拭子中的32个（34.7%）中回收了CLO DNA，这些DNA与目前公认的属于三个衣原体科的物种最为接近：副衣原体科（n = 22）、鼠衣原体科（n = 6）和新衣原体科（n = 3）。所有DNA阳性的沉积物样本（n = 7）都与鼠衣原体科聚类。在活的幼崽和死亡的幼崽中，CLO DNA的回收率没有差异，这表明这些生物是共生的，但无法确定它们作为机会性继发性病原体的潜力。 结论：这是首次在海洋哺乳动物中发现CLO DNA的报告。这一发现值得对英国海岸周围以及世界其他地区的其他海豹种群进行进一步调查，以确定这一发现是独特的，还是比本数据所显示的更为普遍。还需要进一步调查以确定它们是作为纯粹的共生生物存在，还是也可能是海豹中的机会性病原体，以及调查可能的起源，包括它们是否是由于人为影响（包括人类废弃物和农业径流）而产生的。