EB病毒在SCID小鼠体内诱发人B淋巴细胞肿瘤

目的:通过动物体内试验研究EB病毒(EBV)对人正常细胞的致瘤性,并检测我国正常人群对EBV的易感性,试图建立EBV诱发人淋巴细胞肿瘤模型。方法:在严重联合免疫缺陷动物即SCID小鼠体内移植健康成人外周血淋巴细胞(PBL),每鼠腹腔接种1×108个PBL。对接种VCA/IgA阴性献血员PBL的动物,移植后1周内经腹腔注射B95-8标准株EBV悬液作为实验感染,而接种VCA/IgA阳性献血员PBL的动物不再进行实验感染。结果:在接受12名健康成人PBL移植并感染EBV的19只SCID小鼠中,肿瘤诱发率分别为91.7%(11/12名)和84.2%(16/19只鼠)。诱发瘤常见于小鼠腹腔后壁和纵隔,具有侵袭性和致死性,患瘤小鼠平均存活时间65.5天。EBV诱发瘤是结节状实体瘤,显微镜下观察肿瘤细胞呈大裂—无裂混合细胞。组织病理学和免疫病理学研究表明,肿瘤类型是人源B细胞性恶性淋巴瘤。诱发瘤原位分子杂交显示肿瘤细胞核内存在EB病毒小核酸分子EBER-1和人类基因组Alu序列。电子显微镜观察肿瘤细胞核内存在EB病毒颗粒。肿瘤细胞表达EB病毒BZLF1蛋白阳性。结论:SCID/人淋巴细胞嵌合体是研究EBV感染和致瘤性的敏感动物模型,且获得了EBV引起人类正常细胞在体内发生肿瘤的直接依据。因而证实了EBV对人类细胞的致瘤作用,进一步明确机体免疫缺陷因素在肿瘤发生中起重要作

Development of Human B-Cell Lymphomas Induced by Epstein-Barr Virus in SCID Mouse

Objective:In order to confirm the tumorigenecity of Epstein-Barr virus(EBV)to human normal cells by the test in animal body and to detect the Chinese susceptibility to E-BV in fection,the animal model of EBV-induced tumor has been established.Methods:Human peripheral blood lymphocytes(PBLs)were trasplantesd intraperitoneally into severely combined im-munodeficient (SCID)mice by1x10PBLs per mouse.The mice with hu-PBL engraftment from healthy IgA/VCA negative donors were injected intraperitoneally in a week with EBV-containing supernatant from B95-8cell suspension culture(active infection),whereas the mice receiving hu-PBL engraftment from healthy IgA/VCA positive donors were not injected with B95-8supernatant (latent infection).Results:In19hu-PBL/SCID chimerical recipients derived from12donors,the tumor incidences were91.7%for12cases of donor(11/12)and84.2%for19survival SCID mice(16/19)respectively.Another12animals died because of graft-versus-host disease and their average life span was17.5days.EBV-induced tumors were often found in the abdominal cavity or mediastinum which possessed aggressive and fatal features.The average survival time of tumor-bearing mice was65.5days.The EBV-induced neoplasms in SCID mice were nodular tumors.Microscopic observation of tumors showed diffuse arrangement.Histologically the tumors were dominatedy by large-cleaved and non-cleaved mixed cells.Im munohistochemical analysis of tu mors in mice re vealed that LCA(CD45)and L26(human B-cell marker CD20)were positive,but both PS1and UCHL-1(T-cell marker,CD3and CD4RD)were negative.Observation of histopathology and im munopatholo gy demonstrated that the induced tu mors were human B-cell lym phomas.In situ hybridization revealed that the tumor cells contained the EBV encoded small RNA-1,i.e.E-BER-1and Alu sequence of human genome.There were EBV particles in Nuclei of tumor cells ob served by electron mi croscopy.Immunohistochemistry showed positive stain ing of BZLF-1protein in almost all tumor cells.Conclusion:Human PBL/SCID chimeras is a sensitive animal model to study infection and oncogenesis of EB vitrus.This experiment has ob tained the direct causative evidence dealing with EBV associated tumor derived from human normal cells.In the present work,the findings confirmed the oncogenecity of EB virus to human normal cells and defined sig nificant role of the immunodeficiency in the process of tumor develop ment.The re sults suggest the high susceptibility of South Chinese to EBV infection.