Molecular and Immunological Studies on Feline Immunodeficiency Virus

本项目的目的是从分子生物学和免疫学方面进行综合研究，阐明猫免疫缺陷病毒（FIV）的遗传特性，了解该病毒在体内的致病机制。研究仍在继续，但我们得到了以下结果：1）我们从台湾和阿根廷的猫中分别分离出四种和五种FIV株。对它们的env V3-V5区的序列分析显示，台湾分离株属于C亚型，而五个阿根廷分离株中的四个形成了一个新的簇，被命名为E亚型。2）我们建立了新的方法来测量外周血单个核细胞中的病毒负荷和抗FIV的中和抗体滴度。3）获得了识别猫CD 4和CD 8 α分子的单克隆抗体（mAb）。此外，我们克隆了猫CD 8 α和β链的cDNA，并在COS-7细胞中表达 ...更多信息 4）克隆了猫Fas抗原和Fas配体基因。Fas基因全长942 bp，与人和鼠的同源性分别为55.6%和47.9%。Fas配体基因长840 bp，与人和鼠的同源性分别为88.7%和78.2%。Fas抗原和配体在多种组织和几种细胞系中表达。5）构建了FIV AP-1结合位点、vif和ORF-A基因缺失的FIV突变株，并将其接种SPF猫。我们发现vif基因对病毒的感染性和体内生长能力有重要作用。另一方面，我们还发现AP-1结合位点对病毒的生长能力影响不大，而ORF-A基因对病毒的生长能力影响不大，但对病毒的生长能力影响显著。少

The purpose of the project is to clarify the genetic properties of feline immunodeficiency virus (FIV) and to know the pathogenetic mechanism of the virus in vivo by studying comprehensively from the molecular biological and immunological aspects. The study is still continuing but we obtained the following results.1) We isolated four and five FIV strains from cats in Taiwan and Argentina, respectively. Sequence analyzes of their env V3-V5 region revealed that Taiwanese isolates belonged to subtype C and four of the five Argentine isolates formad a new cluster designated as subtype E.2) We established novel methods to measure both the viral burden in the peripheral blood mononuclear cells and the neutralizing antibody titer against FIV.And then, we applied the methods to analyzes of FIV-infected cats.3) We obtained monoclonal antibodies (mAbs) recognizing feline CD4 and CD8 alpha molecules. Further, we cloned the cDNA of feline CD8 alpha and beta chains and expressed them in COS-7 cells … More , and analyzed the sequences of the cDNA and the mAbs.4) We cloned genes of feline Fas antigen and Fas ligand. The Fas gene was 942 bp long and has a homology with human and murine homologues at 55.6 and 47.9% at amino acid level, respectively. The Fas ligand gene was 840 bp long and has a homology with human and murine homologues at 88.7 and 78.2% at amino acid level, respectively. The Fas antigen and the ligand were expressed in various tissues and several cell lines. Further we obtained some evidence that the Fas antigen-ligand system was associated with the apoptosis observed in FIV-infected cats.5) We constructed FIV mutants which deleted AP-1 binding site, vif and ORF-A genes, and inoculated them into SPF cats. We found that vif gene is quite important for the viral infectivity and growth ability in vivo. On the other hand, we also found that the AP-1 binding site has a little responsibility for the viral growth ability, and ORF-A gene is dispensable but responsible for the viral growth ability significantly in vivo. Less