Routes of Hendra Virus Excretion in Naturally-Infected Flying-Foxes: Implications for Viral Transmission and Spillover Risk
Routes of Hendra Virus Excretion in Naturally-Infected Flying-Foxes: Implications for Viral Transmission and Spillover Risk
复制标题
DOI：
10.1371/journal.pone.0140670
复制
发表时间：
2015-10-15
期刊：
影响因子：
3.7
通讯作者：
Smith, Craig
中科院分区：
文献类型：
--
作者：
Edson, Daniel;Field, Hume;Smith, Craig
翼翅目蝙蝠或飞狐是亨德拉病毒(HEV)的自然宿主，这种病毒在澳大利亚东部偶尔会导致马和人类的致命疾病。虽然有强有力的证据表明，尿液是一种重要的感染媒介，可能导致蝙蝠对蝙蝠的传播和蝙蝠对马的传播，但不确定替代排泄途径的相对重要性，如鼻腔和口腔分泌物以及粪便。确定HEV在飞狐体内排泄的潜在途径，对于有效降低马与蝙蝠接触的风险，以及在宿主-病原体模型中确定传播率具有重要意义。这项研究的目的是确定自然感染的飞狐体内HEV排泄的主要途径，其次是确定排泄流行率的物种间差异。2012至2014年间，在昆士兰州东部和新南威尔士州的多个栖息地捕获了来自澳大利亚大陆四个物种中的三个物种(Pteropus Alecto、P.Polocephalus和P.肩峰)的2840只飞狐，并对其进行了采样。从麻醉蝙蝠身上采集了一系列生物样本(尿液和血清，以及泌尿生殖器、鼻腔、口腔和直肠拭子)，并使用针对M基因的qRT-PCR方法检测HEV RNA。42株巴氏巴氏杆菌(n=1410)在至少一份样本中检测到HEV RNA，共检出78份阳性样本，总阳性率为1.76%(78/4436)。尿样(血清、填塞的血细胞、粪便、鼻腔和口腔)病毒RNA的检出率和数量最高，这表明尿液是飞狐和马最有可能的感染源。尿样检测比泌尿生殖道拭子检测更有效，认为前者是首选的诊断样本。血清中HEV RNA的检测与血源性传播一致，与假想的狐狸潜伏期和复发相一致。在小儿麻痹症头疟原虫(n=1168只动物；n=2958个样本)或肩头疟原虫(n=262只动物；n=985个样本)中没有检测到病毒，这表明(与最近的其他研究一致)，在HEV感染动态中，这些物种在流行病学上不如P.alecto重要。就个体动物方法、大样本量以及使用分子分析直接确定感染状态而言，这项研究是前所未有的。这些特征为我们的调查结果的准确性提供了高度的信心，并为更准确地针对马匹风险缓解策略奠定了坚实的基础。
Pteropid bats or flying-foxes (Chiroptera: Pteropodidae) are the natural host of Hendra virus (HeV) which sporadically causes fatal disease in horses and humans in eastern Australia. While there is strong evidence that urine is an important infectious medium that likely drives bat to bat transmission and bat to horse transmission, there is uncertainty about the relative importance of alternative routes of excretion such as nasal and oral secretions, and faeces. Identifying the potential routes of HeV excretion in flying-foxes is important to effectively mitigate equine exposure risk at the bat-horse interface, and in determining transmission rates in host-pathogen models. The aim of this study was to identify the major routes of HeV excretion in naturally infected flying-foxes, and secondarily, to identify between-species variation in excretion prevalence. A total of 2840 flying-foxes from three of the four Australian mainland species (Pteropus alecto, P. poliocephalus and P. scapulatus) were captured and sampled at multiple roost locations in the eastern states of Queensland and New South Wales between 2012 and 2014. A range of biological samples (urine and serum, and urogenital, nasal, oral and rectal swabs) were collected from anaesthetized bats, and tested for HeV RNA using a qRT-PCR assay targeting the M gene. Forty-two P. alecto (n = 1410) had HeV RNA detected in at least one sample, and yielded a total of 78 positive samples, at an overall detection rate of 1.76% across all samples tested in this species (78/4436). The rate of detection, and the amount of viral RNA, was highest in urine samples (>serum, packed haemocytes >faecal >nasal >oral), identifying urine as the most plausible source of infection for flying-foxes and for horses. Detection in a urine sample was more efficient than detection in urogenital swabs, identifying the former as the preferred diagnostic sample. The detection of HeV RNA in serum is consistent with haematogenous spread, and with hypothesised latency and recrudesence in flying-foxes. There were no detections in P. poliocephalus (n = 1168 animals; n = 2958 samples) or P. scapulatus (n = 262 animals; n = 985 samples), suggesting (consistent with other recent studies) that these species are epidemiologically less important than P. alecto in HeV infection dynamics. The study is unprecedented in terms of the individual animal approach, the large sample size, and the use of a molecular assay to directly determine infection status. These features provide a high level of confidence in the veracity of our findings, and a sound basis from which to more precisely target equine risk mitigation strategies.