Rous sarcoma virus is a retrovirus and is the first oncovirus to have been described: it causes sarcoma in chickens.

As with all retroviruses, it reverse transcribes its RNA genome into cDNA before integration into the host DNA.

VZV IS HERPESVIRIDAE

81 當抗體由膜固著（membrane-bound）型式轉變為分泌（secreted）型式時，其原理為：

 DNA 重組（recombination）  RNA 剪接（splicing）

蛋白質裂解（degradation） 新的基因表現（expression of a new gene）

Splicing = Secreted

86 Hereditary angioneurotic edema 的成因是：

因缺乏補體C1 之inhibitor，引起過多bradykinin 及C2 kinin 生成

因缺乏purine nucleoside phosphorylase，因此增加vascular leakage

過高的IgG1 活化引起C2, C4 活性過高，而增加血管通透性

過高的properdin 及factor D 引起過高的血管通透性

ANS a

87 Hyper-IgM syndrome 為何有免疫缺失？

因初級免疫反應製造過多IgM 以致有自體免疫反應發生

因遺傳性的IgM 基因過度活化

因缺乏T cell help 以致B cell 的antibody isotype switching 缺乏

因缺乏NADPH oxidase

ANS C

88 HLA typing 相吻合的陌生人之間的器官移植仍會發生排斥反應，這是因為：

 HLA typing 之判讀不良

兩者之histocompatibility minor antigens 不同

 Clq 造成的細胞性免疫力（Clq-mediated cellular immunity）

趨化激素引起的組織傷害（chemokine-mediated tissue damage）

ANS B

陰道滴蟲: TRICHOMONAS

Scrub typhus is a form of typhus caused by Orientia tsutsugamushi.^[1]

Although it is similar in presentation to other forms of typhus, it is caused by an agent in a different genus, and is frequently classified separately from the other typhi.

ESCHAR