以即時定量聚合酶鏈反應、巢氏反轉錄酶聚合酶鏈反應與間接免疫螢光法調查臺灣地區野鼠感染漢他病毒的盛行率

Abstract

漢他病毒屬於布尼亞病毒科之漢他病毒屬，人類感染後依據病毒種類不同會有出血熱腎症候群或漢他病毒肺症候群。嚙齒類動物為漢他病毒的自然保毒宿主，且每種漢他病毒有其專一性宿主。而人類則為意外宿主，是藉由吸入、食入或接觸到來自於嚙齒類動物的唾液、尿液或糞便之病毒懸浮氣膠而感染。本研究藉巢式反轉錄酶聚合酶鏈反應與間接免疫螢光法調查鼠類感染漢他病毒的盛行率，以窺探台灣各地區鼠類漢他病毒感染的情況，提供防疫之參考。另外，由於鼠類感染漢他病毒後會持續性帶原，本論文亦藉由即時定量聚合酶鏈反應檢測鼠隻各臟器中的病毒量高低，以及比較在自然宿主與過剩宿主 (spillover host) 間是否有差異。盛行率調查結果得知台灣鼠類感染病毒株為首爾型漢他病毒，彼此之核酸序列之相似性達 95.8-100 %，總盛行率為 24.69 % (79/320)，以溝鼠為主要宿主，但是亦有錢鼠、黃胸鼠、鬼鼠等過剩宿主的發現。季節分佈為全年皆有，但多集中於春天、秋天與冬天 (但未達統計學上顯著差異，P>0.05)。台灣南部與外島地區的帶原率高於東部地區 (但未達統計學上顯著差異，P>0.05)。病毒於臟器的分布以肺臟為主要儲存場所，平均病毒量為 6.308 x 103 ± 4.110 x 101 copies/mg，但低於前人以人工感染漢他病毒肺症候群無名病毒實驗的病毒量。且過剩宿主體內的病毒量少於專一性宿主，符合漢他病毒感染專一性宿主可能為長期共同演化而來，非常適應於其宿主體內之推測。

Hantaviruses, which belonged to the family Bunyaviridae and genus Hantavirus, cause two serious and often fatal human diseases, namely hemorrhagic fever with renal syndrome (HFRS) in Eurasia and hantavirus pulmonary syndrome (HPS) in Americas. In nature, hantaviruses are exclusively maintained in the populations of their specific rodent hosts and cause a persistent, asymptomatic infection. Humans, as accidental hosts, become infected by inhaling or ingesting or contacting with virus contaminated aerosol generated from urine, feces, and/or saliva shedded by infected rodents. To provide the basic epidemiological information for the disease control, we use nested reverse transcription polymerase chain reaction (RT-PCR) and immunoflurescence assay to investigate the hantavirus infection rate in rodent population in Taiwan. Since rodents are persistent infected with hantavirus, we used the real-time quantitative polymerase chain reaction to evaluate the virus load in various tissues, and compared the viral load between the nature hosts and spillover hosts. The hantavirus strains prevalent in Taiwan were Seoul virus (SEOV), and the sequence homology among the SEOV strains were found to be 95.8-100 %. There were a total of 320 rodents captured and the virus prevalence was 24.69 %. Rattus norvegicus was the most common carrier and other spillover hosts included Suncus murinus or Rattus flavipectus or Bandicota indica. The hantavirus could be detected all the year round but especially common in the spring, fall and winter, although such a difference was not statistically significant (P＞0.05). The hantavirus prevalence in rodent in Southern Taiwan and offshore islets was much higher than in Eastern Taiwan, although such a difference was not statistically significant (P＞0.05). By real time RT-PCR, lungs of the carrier rodent had the highest mean viral load (6.308 x 103 ± 4.110 x 101 copies/mg), however, it was lower than the virus load of previous study using Sin Nombre virus (SNV) in experimentally infected rodents. It is suggested that the virus load in the experimental infection model is different from the nature infection. The viral load in the spillover host is lower than that in the nature host, suggesting further support on the notion that hantavirus co-evolved with their specific hosts over a very long time.