Establishment of the gene therapy model for protecting retroviral infection

为建立逆转录病毒诱导的疾病的基因治疗模型，利用小鼠Friend白血病病毒（FLV）系统进行了实验研究。我们转导了野生小鼠中发现的嗜亲性小鼠白血病病毒的宿主抗性基因Fv-4^r基因。该基因编码截短形式的ENV蛋白，该截短形式的ENV蛋白能够与病毒的受体结合，阻断病毒对同一受体特异性的感染。首先，我们寻找产生具有良好表达效率的基因转移系统的条件。转导的Fv-4^r基因在造血细胞中表达良好，因此，我们可以通过移植转导Fv-4^r的骨髓细胞来产生骨髓嵌合体小鼠。在小鼠体内，转导了Fv-4^r基因的小鼠对FLV感染具有抵抗力。接下来，在骨髓嵌合体小鼠中，研究了转导的Fv-4^r基因的抵抗机制。利用FLV-ENV-GFP系统，阐明了Fv-4^r基因产物在骨髓嵌合体小鼠中的受体干扰效应，并分析了Fv-4^r基因在免疫抑制宿主中的治疗效果。Fv-4^r基因治疗在胸腺切除小鼠中也有效，综上所述，我们的基因治疗模型对抗FLV诱导的疾病是有效的，并且疗效是通过基因产物的受体干扰机制传递的。由于这种疗法即使在宿主免疫抑制的情况下也有效，因此艾滋病等逆转录病毒引起的人类疾病也将成为这种基因疗法的目标。

To establish the gene therapy model for retrovirus-induced disease, experiments using murine Friend leukemia virus (FLV) system were performed. We transduced the Fv-4^r gene that was the host resistant gene against ecotropic murine leukemia virus found in wild mouse. This gene encodes a truncated form of ENV protein which would bind to the receptor of the virus to block viral infection of the same receptor-specificity.First of all, we searched for the condition to produce gene transfer system with good expression efficacy. Transduced Fv-4^r gene was well expressed in the hematopoietic cells and thus we could generate the bone marrow chimera mice by transplantation of Fv-4^r transduced bone marrow cells. Mice transduced with Fv-4^r gene were resistant to FLV-infection.Next, mechanisms for the resistance by transduced Fv-4^r gene in bone marrow chimera mice were examined. By using FLV-ENV-GFP system, we clarified the receptor interference effect of Fv-4^r gene product in bone marrow chimera mice.Finally, we analyzed the Fv-4^r gene therapy effect in immunosuppressed hosts. Fv-4^r gene therapy was also effective in thymectomized mice.In summary, our gene therapy model was effective for resisting FLV-induced disease and the efficacy was transferred through receptor interference mechanism by the gene product. Because the therapy was effective even under the immunosuppressed condition of the hosts, human diseases by retrovirus such as AIDS would also be the target of this kind of gene therapy.