Treatment of Leukocyte Adhesion Deficiency by Foamy Virus Vectors

描述（由申请人提供）： 本提案将开发泡沫病毒（FV）载体用于治疗白细胞粘附缺陷症（LAD）。在LAD中，CD 18基因突变阻止了白色血细胞（白细胞）迁移到组织中，导致危及生命的细菌感染。自体造血干细胞（HSCs）经CD18表达载体转导后移植可治愈该疾病。然而，人类和大型动物HSC难以有效地扩增，并且已经显示基于鼠白血病病毒（MLV）的整合载体通过激活附近的细胞原癌基因而引起白血病。FV是逆转录病毒，基于它们的载体能够有效地将基因递送到HSC。它们不是致病性的，因此FV载体可能比其他类型的逆转录病毒载体更安全。在此，FV载体将用于将犬CD 18基因递送至患有犬LAD（CLAD）的犬的HSC。然后，这些HSC将被移植到CLAD犬中，在那里它们将分化成表达CD18的成熟血细胞。如果获得足够的CD18水平，移植犬的临床症状应有所改善，并避免因感染而过早死亡。这些数据将用于确定用FV载体将基因转移到犬HSC中的效率。整合位点分析将确定有多少不同的转导细胞克隆有助于血液形成，以及是否存在特定克隆的选择性扩增。移植的动物将被长期跟踪，以寻找潜在的副作用，包括白血病的发展。将测试用于促进移植细胞植入的不同预处理方案。将评估使用不同启动子的FV载体。将FV载体与表达CD 18的类似慢病毒载体进行比较，以确定用于LAD的HSC基因治疗的最佳载体类型。这些实验将确定FV载体是否可以有效地将基因转移到犬骨髓干细胞，以及表达CD 18的FV载体是否可以治愈CLAD。这可能会导致新的治疗方法的发展，为左前降支，以及其他遗传或获得性血液疾病，这可能会改善许多美国人的健康。如果被证明是安全和有效的，在拟议的实验中测试的FV载体可以用于人类临床试验，以治疗LAD。

DESCRIPTION (provided by applicant): This proposal will develop foamy virus (FV) vectors for the treatment of leukocyte adhesion deficiency (LAD). In LAD, mutations in the CD18 gene prevent the migration of white blood cells (leukocytes) into tissues, resulting in life-threatening bacterial infections. Transplantation of autologous hematopoietic stem cells (HSCs) transduced by CD18-expressing vectors could cure this disease. However, human and large animal HSCs are difficult to transduce efficiently, and integrating vectors based on murine leukemia virus (MLV) have been shown to cause leukemia by activating nearby cellular proto-oncogenes. FVs are retroviruses and vectors based on them are able to efficiently deliver genes to HSCs. They are not pathogenic so FV vectors may be safer than other types of retroviral vectors. Here FV vectors will be used to deliver the canine CD18 gene to the HSCs of dogs with canine LAD (CLAD). These HSCs will then be transplanted into CLAD dogs, where they will differentiate into mature blood cells that express CD18. If adequate CD18 levels are obtained, the transplanted dogs should improve clinically and avoid an early death due to infections. The data will be used to determine the efficiency of transferring genes into canine HSCs with FV vectors. Integration site analysis will establish how many different transduced cell clones contributed to blood formation, and whether there was selective expansion of particular clones. The transplanted animals will be followed long-term to look for potential side effects, including the development of leukemia. Different conditioning regimens used to promote engraftment of transplanted cells will be tested. FV vectors that use different promoters will be evaluated. FV vectors will be compared to similar lentiviral vectors that express CD18 to determine the best type of vector for HSC gene therapy of LAD. These experiments will determine if FV vectors can efficiently transfer genes to canine bone marrow stem cells, and if FV vectors expressing CD 18 can cure CLAD. This could lead to the development of new treatments for LAD, as well as other genetic or acquired blood diseases, which could improve the health of many Americans. If shown to be safe and effective, the FV vectors tested in the proposed experiments could then be used in human clinical trials to treat LAD.