The enhanced efficacy of herpes simplex virus by lentivirus mediated VP22 and cytosine deaminase gene therapy against glioma

Despite the comprehensive treatment of surgery following by concurrent radiochemotherapy, the prognosis of malignant glioma remains unsatisfactory with an awful median survival time of only 12-18 months. This might be improved by the development of oncolytic herpes simplex virus. However, the biggest challenge of recombinant herpes simplex virus (rHSV) lies in their limited therapeutic efficiency in clinical trials. This study aims to enhance the efficacy of rHSV against glioma by a HSV-1 tegument protein VP22 modified cytosine deaminase/5-flurocytosine (CD/5-FC) suicide gene system. Stable glioma cell lines carrying CD or VP22-CD fusion gene were successfully obtained by lentiviral infection following Fluorescence-activated cell sorting. The lethal effect of the prodrug 5-FC was significantly increased in the transduced VP22-CD glioma cells compared to the transduced CD glioma cells. Interestingly, VP22 was found to elicit the enhanced efficacy of rHSV-1 against glioma. Furthermore, we detected a synergistic efficacy of rHSV-1 combined with lentivirus mediated VP22 and CD suicide gene therapy in the orthotopic glioma xenograft models. In conclusion, we successfully established the stable cell lines carrying VP22-CD fusion genes. The incorporation of VP22 further induced an enhanced efficacy of rHSV-1 as well as CD suicide gene therapy respectively and synthetically in vitro. Also, we demonstrated an increased therapeutic benefit of rHAV-1 by VP22 modified CD gene therapy against glioma in vivo.