He X S, Chen H S, Chu K, Rivkina M, Robinson W S
Division of Infectious Diseases, Stanford University School of Medicine, Stanford, CA 94305, USA.
Proc Natl Acad Sci U S A. 1996 Jul 9;93(14):7274-8. doi: 10.1073/pnas.93.14.7274.
There is a need for more effective therapy for chronic virus infections. A principle natural mechanism for elimination of virus-infected host cells is activation of viral antigen-specific cytotoxic T lymphocytes (CTL). In an effort to develop methods of inducing virus-specific CTL responses that might be utilized in therapy of virus infections, we have investigated the effect of B7, a costimulatory factor for T-cell activation. In this study we show that delivery of genes encoding human B7-1 and a viral antigen in the same recombinant viral vector to cells of mice induces a greater viral antigen-specific CTL response than does similar delivery of the viral antigen gene alone. Two recombinant adenovirus vectors were constructed with the foreign genes inserted in the early region 3. One of them (Ad1312) directed expression of the surface antigen gene of hepatitis B virus (HBS); the other (Ad1310) directed coexpression of HBS and human B7-1 (CD80) by means of an internal ribosomal entry site placed between the two coding sequences. When inoculated into BALB/c mice, both vectors induced a viral surface antigen-specific CTL response. The response induced by Ad1310 was stronger than that by Adl312 as measured by a chromium release assay for CTL activity and limiting dilution analysis for CTL precursor frequency, indicating that the B7-1 gene co-delivered with the HBS gene had an enhancing effect on the CTL response against surface antigen. Ad1310 also induced a higher titer of antibody against surface antigen than did Ad1312. This result suggests that expression of a costimulatory protein and a viral antigen in the same cells in vivo induces stronger immune responses than expression of the antigen alone. This could be a novel strategy for development of both preventive and therapeutic vaccines against infectious agents.
对于慢性病毒感染，需要更有效的治疗方法。清除病毒感染宿主细胞的一种主要自然机制是激活病毒抗原特异性细胞毒性T淋巴细胞（CTL）。为了开发可能用于病毒感染治疗的诱导病毒特异性CTL反应的方法，我们研究了T细胞激活的共刺激因子B7的作用。在本研究中，我们表明，将编码人B7-1和病毒抗原的基因以相同的重组病毒载体递送至小鼠细胞，比单独递送病毒抗原基因能诱导更强的病毒抗原特异性CTL反应。构建了两种重组腺病毒载体，外源基因插入早期区域3。其中一种（Ad1312）指导乙型肝炎病毒表面抗原基因（HBS）的表达；另一种（Ad1310）通过置于两个编码序列之间的内部核糖体进入位点指导HBS和人B7-1（CD80）的共表达。当接种到BALB/c小鼠中时，两种载体均诱导了病毒表面抗原特异性CTL反应。通过CTL活性的铬释放试验和CTL前体频率的有限稀释分析测量，Ad1310诱导的反应比Adl312更强，表明与HBS基因共同递送的B7-1基因对针对表面抗原的CTL反应有增强作用。Ad1310还比Ad1312诱导了更高滴度的针对表面抗原的抗体。该结果表明，体内同一细胞中共刺激蛋白和病毒抗原的表达比单独抗原的表达诱导更强的免疫反应。这可能是开发针对感染因子的预防性和治疗性疫苗的一种新策略。
