臺灣小型哺乳類動物中大鼠E型肝炎病毒之分子檢驗

Abstract

囓齒類動物是人畜共通傳染病的重要媒介，包括1.漢他病毒症候群2.鉤端螺旋體病3.大鼠E型肝炎病毒等，這對於公共衛生構成了重大風險。這項研究以臺灣疾病管制署 早期進行的小規模研究為基礎，擴大了臺灣各地小型哺乳類動物中大鼠E型肝炎病毒的調查範圍，旨在評估其盛行率和遺傳多樣性。 2023年3月至2024年11月，從17個縣市捕獲了小型哺乳類動物847隻，其中包括溝鼠、小黃腹鼠、亞洲家鼠、家鼷鼠、田鼷鼠、赤背條鼠、鬼鼠、刺鼠、臭鼩。使用針對 ORF1 RdRp 區域的巢式反轉錄聚合酶鏈反應 (nested-RT-PCR) 檢測大鼠E型肝炎病毒，並對陽性樣本進一步分析 ORF1 和 ORF2 區域。大鼠E型肝炎病毒檢測呈陽性的動物有5隻，其中溝鼠4隻，家鼷鼠1隻，盛行率為1.43% (5/350)。親緣關係分析結果顯示，與 GenBank 中的參考序列相比，相似度範圍為 91.76% 至 93.55%，突顯了與已知病毒株的遺傳相似性和獨特的變異。從溝鼠樣本(R2023-484) 中檢測出的病毒成功組裝出接近全長的基因組（6662 個核苷酸），其他溝鼠樣本增幅出大部分基因組進一步支持了該物種作為主要宿主的作用，而家鼷鼠樣本遇到的增幅困難顯示病毒株變異性更大，因此需要使用其他引子和最佳化PCR 條件。從地理上看，臺灣北部和南部均檢測到陽性樣本，顯示分佈廣泛。低於臺灣疾病管制署報告的鼠血清中大鼠E型肝炎病毒陽性率，可能是由於方法或環境差異。這些發現呈現大鼠E型肝炎病毒的人畜共通傳染潛力及持續監測和基因研究的重要性，以便增強我們對其流行病學的了解，改進檢測方法並評估公共衛生影響。

Rodents are critical vectors of zoonotic diseases, including the rat hepatitis E virus (rat HEV), which poses significant public health risks. Building upon earlier small-scale studies conducted by the Taiwan Centers for Disease Control (TWCDC), this study broadens the investigation of rat HEV in small mammals throughout Taiwan, aiming to assess its prevalence and genetic diversity. Between March 2023 and November 2024, 847 small mammals were captured from 17 counties, including Rattus norvegicus, Rattus losea, Rattus tanezumi, Mus musculus, Mus caroli, Apodemus agrarius, Bandicota indica, Niviventer coninga and Suncus murinus. Nested reverse transcription polymerase chain reaction (nested-RT-PCR) targeting the RNA-dependent RNA polymerase (RdRp) region of ORF1 was employed to detect rat HEV RNA, with positive samples further analyzed for the ORF1 and ORF2 regions. Five animals tested positive for rat HEV, including four R. norvegicus and one M. musculus, resulting in a positive rate of 1.43% (5/350). Phylogenetic analysis revealed identities ranging from 91.76% to 93.55% when compared to reference sequences in GenBank, highlighting both genetic similarities to known strains and unique variations. A near-full-length genome (6662 nucleotides) was successfully assembled from R. norvegicus (R2023-484). The amplification of large segments of the genomes in other R. norvegicus samples further supports the role of this species as a primary host. While amplification challenges encountered with M. musculus samples indicated greater strain variability, necessitating the use of alternative primers and optimized PCR conditions. Geographically, positive samples were detected in both northern and southern Taiwan, indicating a widespread distribution. The observed liver positive rate lower than the positive rates reported by the Taiwan CDC, possibly due to methodological or environmental differences. These findings underscore the zoonotic potential of rat HEV and highlight the importance of continued surveillance and genetic research to enhance our understanding of its epidemiology, improve detection methods, and assess public health implications.