Vaccination against δ?Retroviruses: The Bovine Leukemia Virus Paradigm

Bovine leukemia virus (BLV) and human T-lymphotropic virus type 1 (HTLV-1) are closely related δ-retroviruses that induce hematological diseases. HTLV-1 infects about 15 million people worldwide, mainly in subtropical areas. HTLV-1 induces a wide spectrum of diseases (e.g., HTLV-associated myelopathy/tropical spastic paraparesis) and leukemia/lymphoma (adult T-cell leukemia). Bovine leukemia virus is a major pathogen of cattle, causing important economic losses due to a reduction in production, export limitations and lymphoma-associated death. In the absence of satisfactory treatment for these diseases and besides the prevention of transmission, the best option to reduce the prevalence of δ-retroviruses is vaccination. Here, we provide an overview of the different vaccination strategies in the BLV model and outline key parameters required for vaccine efficacy.     

表达胃癌MG7-Ag模拟表位的减毒鼠伤寒杆菌疫苗的研制和初步鉴定

目的 研制可表达胃癌MG7－Ag模拟表位的减毒鼠伤寒杆菌疫苗。方法 将NcoI位点和MG7－Ag模拟表位编码序列的互补序列设计到上游引物的5′端。以含有HBcAg全序列的质粒p1.2Ⅱ为模板，通过PCR扩增，获得MG7－Ag模拟表位与HBcAg的融合基因。将目的基因插入载体pUCm-T，经酶切鉴定和序列测定证实后，再亚克隆至与减毒鼠伤寒杆菌X4550互补的质粒pYA3341中，再以此重组质粒转化减毒鼠伤寒杆菌X4550。结果 序列测定证实，PCR产物为胃癌MG7－Ag模拟表位与HBcAg的融合基因片段；最终得到含有目的基因片段的重组表达载体pYA3341。重组质粒在X4550中的表达产物，经Western blot表明，在相对分子质量（Mr)约在22000处有1条可与抗MG7 mAb特异性结合的多肽表位。结论 成功地研制可表达胃癌MG7－Ag模拟表位减毒鼠伤寒杆菌疫苗，为进一步研究其在胃癌免疫治疗中的作用奠定了基础。     

随机肽库筛选赭曲霉毒素A模拟表位及其应用

目的从噬菌体随机肽库中筛选模拟赭曲霉毒素A表位的噬菌体粒子,并以其替代毒素建立免疫学检测方法。方法以抗赭曲霉毒素A的单克隆抗体为配基,免疫亲和筛选以融合蛋白形式表达在丝状噬菌体M13外壳蛋白Ⅲ上的随机七肽库,以ELISA方法鉴定阳性克隆,同时进行DNA测序确定插入七肽的氨基酸序列。结果经过4轮淘选,共筛选到11株能与该抗体特异性结合的阳性克隆,且该结合能被赭曲霉毒素A阴断,模拟表位的共有序列为:异亮氨酸—精氨酸—脯氨酸—蛋氨酸—缬氨酸—X—X,X为任意氨基酸。以其中阻亲和力最强的克隆(P2)建立了竞争ELISA检测方法,线性范围为200~8000pg/ml,检测下限为150pg/ml。结论噬菌体展示技术可成功筛选到赭曲霉毒素A模拟表位,筛选到的噬菌体粒子可作为毒素的替代品建立免疫学分析方法。