中 文 摘 要

登革(Dengue)是一經種由埃及斑蚊或白線斑蚊媒介的病毒，感染登革病毒的病人表現出不同程度的臨床症狀，從輕微可自然痊癒的登革熱(Dengue fever)，到發展成嚴重性可能威脅生命的登革出血熱 (Dengue hemorrhagic fever)或登革休克症(Dengue shock syndrome)，但是對於登革病毒的致病機轉至今尚不明確。因此在本篇論文中，我們探討登革病毒和人類B細胞的相互關係, 藉以了解病毒可能的致病機轉。首先利用B細胞株 (Raji)感染病毒，確認病毒可在B細胞內生長。再者我們發現自人類分離的B細胞, 經病毒感染後，可偵測到病毒的生長，以RT-PCR的方法，偵測病毒負股RNA，以螢光免疫染色法偵測到病毒的envelope、core及nonstructural 抗原, 以上實驗結果證實病毒可在B細胞複製繁殖的現象。此外，登革病毒的免疫血清對病毒再B細胞的生長有增強作用 (antibody-dependent enhancement)。另外，實驗結果顯示受病毒感染後的B細胞會產生較高量的IL-6與TNF-a。由於先前的研究顯示, 登革病毒主要是感染單核球細胞, 但當我們比較人類B細胞及單核球細胞發現時，B細胞在支持病毒生長、抗體增強作用現象與細胞激素表現的情況和單核球受感染的情況類似。
綜合以上結果發現登革病毒確實可以感染B細胞並且在細胞內複製，此外，在比較人類B細胞及單核球細胞在登革病毒感染後的現象，顯示人類B細胞也許是登革病毒的另一主要感染的標的細胞，在登革病毒的致病機轉上可能扮演一個重要的角色。

ABSTRACT
Dengue virus (DV) infection is a major problem in public health because it can cause fatal diseases such as dengue hemorrhagic fever and dengue shock syndrome. Unfortunately, there is no specific antiviral treatment or prophylaxis vaccine because the lack of understanding of pathogenesis. Even the most important question, which cells are infected by virus in humans remains to be determined. Monocytes have long been assumed to be the major virus producer, however, recent reports demonstrated that most DV was found in B cells but not in monocytes of peripheral blood mononuclear cells of infected patients. Using B cell line, my research established that DV2 (PL 046) replicated in Raji cells from 4 to 120 hours post infection at a multiplicity of infection (MOI) of 10 and that a 1:60,000 dilution of human DV3 immune serum (5 fold beyond the neutralizing titer) yielded antibody dependent enhancement effect. Meanwhile, I investigated DV infection, antibody-enhanced virus infection, and cytokines responses of human primary B cells and compared them with those of monocytes. The presence of replication template (negative strand RNA intermediate), virus antigens (envelope, core and nonstructural proteins), and increasing amount of viruses in infected B cells indicated the DV actively replicated in B cells. Additionally, the levels of virus replication, antibody-enhanced virus replication, and cytokine response observed in B cells are comparable to those in monocytes. The results indicated cells support DV growth and may play an important role in the pathogenesis of DV-induced disease.

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