VIRAL ETIOLOGY OF SYSTEMIC LUPUS ERYTHEMATOSUS

系统性红斑狼疮(SLE)是一种以产生抗dsDNA抗体为特征的慢性自身免疫性疾病。系统性红斑狼疮的病因尚不清楚，但已推测病毒可能起一定作用。一种经常与SLE有关的病毒是Epstein-Barr病毒(EBV)，一种能够建立潜伏感染的B细胞营养病毒。在年轻SLE患者的血清中发现了高滴度的EBV抗体。DNA本身不具有免疫原性，但对多瘤病毒T抗原的研究表明，这种病毒DNA结合蛋白与宿主DNA的结合可以使其产生免疫原性，并引发抗双链DNA反应。这个项目的目的是确定EBV，DNA结合蛋白，如EBNA-1，在与宿主DNA结合后是否能诱导产生抗双链DNA抗体。由于小鼠不允许EBV感染，表达EBNA-1的一种方式将是用可以在小鼠细胞中表达EBNA-1的EBV载体肌肉免疫小鼠。这些小鼠的血清将被检测是否存在EBNA1抗体。随后将对携带EBNA-1抗体的小鼠进行dsDNA抗体检测。EBNA-1与dsDNA的结合是产生抗dsDNA抗体的关键。为了证明这一点，我们将构建缺乏结合DNA能力的突变体。将用这些突变体对小鼠进行免疫，以确定它们是否失去了诱导抗dsDNA抗体的能力。转EBNA-1序列的小鼠也将接受抗dsDNA抗体的检测。如果转基因小鼠对EBNA-1和EBNA-1-DNA复合体具有耐受性，则表达转基因的B细胞将被转移到野生型小鼠中，并将检测来自受体的血清以产生抗dsDNA抗体。

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease characterized by the production of anti-dsDNA antibodies. The etiology of SLE is unknown but it has been postulated that viruses may play a role. One virus that has frequently been implicated in SLE is Epstein-Barr virus (EBV), a B-cell trophic virus capable of establishing a latent infection. High titers of antibody to EBV are found in the sera of young SLE patients. DNA by itself is not immunogenic, but studies with the polyoma virus T antigen have shown that the binding of this viral DNA binding protein to host DNA can render it immunogenic, and trigger an anti-dsDNA response. The aim of this project is to determine whether an EBV, DNA binding protein such as EBNA-1 can elicit the production of anti-dsDNA antibodies after binding to host DNA. Since mice are not permissive for EBV infection, one way to express EBNA-1 will be to immunize mice intramuscularly with EBV based vectors that can express EBNA-1 in mouse cells. Sera from these mice will be assayed for the presence of antibodies to EBNA1. Mice with antibodies to EBNA-1 will be subsequently tested for antibodies to dsDNA. It is proposed that the binding of EBNA-1 to dsDNA is critical for anti-dsDNA antibody production. To demonstrate this, mutants will be constructed that lack the ability to bind DNA. Mice will be immunized with these mutants to determine if they loose their capacity to elicit anti-dsDNA antibodies. Mice transgenic for the EBNA-1 sequence will also be tested for the presence of anti-dsDNA antibodies. If transgenic mice are tolerant to EBNA-1 and EBNA-1-DNA complexes, then B-cells expressing the transgene will be transferred into wild type mice and sera from the recipients will be assayed for the production of anti-dsDNA antibodies.