- 學位論文
臺灣鋏蠓攜帶病原體潛在性與吸血源之研究
Pathogen-vector potentials and blood-meal sources of Forcipomyia taiwana
摘要
臺灣鋏蠓（Forcipomyia taiwana）俗稱為小黑蚊，是一種體型細小之蠓科昆蟲，其雌成蟲會叮咬人體裸露之部位來吸食血液。近年來臺灣鋏蠓之危害問題日益嚴重，臺灣本島目前除屏東與臺東地區外，其餘各地山邊村落皆有肆虐記錄。因臺灣鋏蠓雌成蟲具吸血行為，有傳播疾病的可能性，且部份人畜共通傳染病可藉昆蟲在人與動物間傳播，為此有探討臺灣鋏蠓攜帶病原體與吸血對象的必要性。在臺灣鋏蠓猖獗區域採集雌成蟲，萃取樣品核酸後進行病原體檢測與吸血源分析。病原體攜帶潛在性研究部份，目前以病毒類病原體為主要偵測對象，尤其針對節肢動物媒介病毒。檢體利用各病毒屬專一性引子進行PCR，執行人類致病性病毒之監測。在臺灣鋏蠓吸血源研究部份，利用PCR-RFLP技術分析臺灣鋏蠓野外吸食血液後體內所含之細胞色素b基因體，依據預期之片段多型性圖譜進行物種鑑別。臺灣中南部縣市樣品之病毒監測結果中，目前只檢出HBV陽性訊號，且經序列分析後證實為HBV基因體。由此推測野外採集之臺灣鋏蠓檢體內的確含有HBV基因體，但病毒是否會在雌成蟲體內繁殖甚至藉此進行傳播則尚待研究。臺灣鋏蠓檢體分離之HBV基因體序列經遺傳演化樹分析後，顯示此分離株為基因型B與C，和臺灣流行株結果一致。利用半定量PCR分析HBV存於臺灣鋏蠓體內時間與數量變化之相關性的結果顯示，病毒量在樣品吸食HBV血液後一天有增加現象，但隨即逐日降低。在利用PCR-RFLP分析臺灣鋏蠓吸血源之結果中，多次分析結果皆以人的圖譜為主，只出現一次預期豬的圖譜，顯示可能仍以人類為主要吸血對象。由於呈現豬圖譜的樣品採集地為臺灣野豬活動範圍，其產物進行序列分析後證實為野豬的cytb基因體，因此推論臺灣野豬為臺灣鋏蠓之吸血對象。
並列摘要
The Forcipomyia taiwana (Diptera: Ceratopogonidae) are a kind of diurnal midges. The female midges could engorge human blood to influence daily life of human. In recent years, the population of F. taiwana expanded quickly in Taiwan, except Pingtung and Taitung Country. Because of blood-sucking nature, diseases can probably be transmitted by female midges during bit. Some zoonoses could transmit by insects between human and other animal, the blood-sucking target of F. taiwana is an important subject. Thus, the pathogen-vector potentials and blood-meal sources of F. taiwana are our research issues. Female midges were collected from various areas infested with F. taiwana in Taiwan. After nucleic acids extraction, the samples were used to analyze the pathogen-vector potentials and blood-meal sources of F. taiwana. The detection of viral pathogen was performed by PCR using genus-specific primer. In order to analyze the blood-meal sources of F. taiwana, PCR-RFLP of cytochrome b gene was used to identify the source of the blood in sample. In the study of pathogen-vector potentials, the Hepatitis B virus carried by F. taiwana was confirmed for the first time in our study. We detected HBV positive signal in the sample collected from different seasons and areas in Taiwan. According to the phylogenetic analysis, the HBV isolated from F. taiwana were genotype B and C, it was the same as the prevalent strain in Taiwan. The results of semi-quantitative PCR show that the copy number of HBV genome within F. taiwana was increased at one day post blood-feeding. These resuls imply the correlation between HBV and F. taiwana is very important. In the blood-meal source analysis, the PCR-RFLP pattern of human is the predominance, it implys human could be the main blood-meal source of F. taiwana. The swine’s pattern in the PCR-RFLP analysis was also obtained and confiemed by sequecncing. According to the result, we suggest that swine could be the blood-meal source of F. taiwana.