假性狂犬病毒(pseudorabies virus, PrV)屬於豬隻的一種疱疹病
毒。此病毒具有廣泛性的自然宿主，包含許多的哺乳類動物，但對人類是一種非致病性的病毒。在本實驗室先前的研究中，利用簡單的同源重組的方式，將假性狂犬病毒改造成gD/gE/TK缺陷的病毒來做疫苗基因的傳送載體。在治療癌症的方法中，已經有研究指出利用抑制血管新生來抑制腫瘤的生長以及利用病毒會專一性在腫瘤細胞中複製來殺死腫瘤細胞的特性來治療腫瘤。因此在這建立好的系統中，第一部分利用同源重組的方式將會抑制血管新生的endostatin基因送入假性狂犬病毒載體中，並將此病毒命名為YP1，進一步探討抑制小鼠腦瘤發展的情形。實驗結果顯示YP1確實帶有endostatin的基因，並且可表現具有生物活性的蛋白質來抑制內皮細胞的增生。在小鼠腦瘤的動物模式中，也發現在經由YP1治療的小鼠其腫瘤的生長速度比對照組來得慢，且存活也比對照組來得好。在第二個部分中，有研究指出Her2/neu蛋白質在許多的腫瘤細胞中有過度表現的情形，這些腫瘤包含有肺癌、乳癌、口腔癌以及膀胱癌。因此我們利用具有選擇性複製的病毒來殺死這些Her2/neu過度表現的腫瘤細胞。經由同源重組的方式，我們重組出帶有Her2/neu啟動子的病毒，並將此病毒命名為YP2。在實驗的結果中得知YP2可以將Her2/neu過度表現的
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CF-1、HCDB-1以及TSGH8301腫瘤細胞殺死，但對於Her2/neu不表現的細胞則不會有任何細胞病變的產生。在膀胱癌的小鼠模式中，我們連續七次將YP2病毒打入腫瘤細胞中進一步觀察其抑制腫瘤細胞生長的情形。結果顯示YP2治療的小鼠其腫瘤明顯比對照組來得小，而且存活也有明顯的延長。因此由以上的實驗證實經由同源重組的YP1和YP2兩種病毒確實有抑制小鼠腫瘤生長的情形，而且也可以增加小鼠的存活時間。假性狂犬病毒對人類是一種非致病性的病毒，而且經由簡單的同源重組的方法我們可以植入任何有興趣的治療基因。因此或許可以將假性狂犬病毒當作是一個更具有安全性
的病毒載體來治療癌症。

Pseudorabies virus (PrV), a herpesvirus of swine, is a neurotropic herpesvirus with a wide host-range, including several mammalian species, but is non-pathogenic for humans. We have previously constructed a gD/gE/TK-negative PrV mutant, which can be used as a viral vector for gene transfer. Targeting tumor angiogenesis and replication-selective oncolytic virus have been reported to kill tumor cells. In this study, we constructed a PrV vector carrying endostatin gene, the most potent inhibitor of tumor angiogenesis, for the treatment of brain tumor. Besides, previous studies indicated that Her2/neu is overexpressed in many human cancers, including lung, breast, oral and bladder cancers. Using homologous recombination method, PrV-CD5-ES and PrV-Her2P oncolytic virus were generated, and designated YP1 and YP2. In in vitro study, the expression of endostatin was detected by RT-PCR and its biological activity was determined by endothelial cell proliferation assay after YP1 infection. In C6 glioma-bearing SCID mice, the tumor in YP1-treated mice was significant decreased and survival was also prolonged. The YP2 virus could lyse CF-1, HCDB-1 and TSGH8301 cells, which were Her2/neu-overexpressing cancer cells, but not NIH3T3 cells without Her2/neu expression. In in vivo study, the YP2 virus could effectively inhibit tumor growth in mice bearing bladder cancer and survival was significant enhanced in YP2-treated mice. Because PrV is a non-pathogenic virus for humans, these viruses may serve as safer viral vectors for cancer gene therapy.

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