Pepperl S, Münster J, Mach M, Harris J R, Plachter B
Institute for Virology, University of Mainz, Germany.
J Virol. 2000 Jul;74(13):6132-46. doi: 10.1128/jvi.74.13.6132-6146.2000.
Infection of fibroblast cell cultures with human cytomegalovirus (HCMV) leads to the production of significant amounts of defective enveloped particles, termed dense bodies (DB). These noninfectious structures contain major antigenic determinants which are responsible for induction of both the humoral and the cellular immune response against HCMV. We tested the hypothesis that, by virtue of their unique antigenic and structural properties, DB could induce a significant immune response in the absence of infectious virus. Mice were immunized with gradient-purified DB, which were either left untreated or subjected to sequential rounds of sonication and freeze-thawing to prevent cellular entry. Titers of neutralizing antibodies induced by DB were in a range comparable to levels present in convalescent human sera. The virus-neutralizing antibody response was surprisingly durable, with neutralizing antibodies detected 12 months following primary immunization. The HCMV-specific major histocompatibility complex class I-restricted cytolytic T-cell (CTL) response was assayed using mice transgenic for the human HLA-A2 molecule. Immunization with DB led to high levels of HCMV-specific CTL in the absence of de novo viral protein synthesis. Maximal total cytolytic activity in mice immunized with DB was nearly as efficient as the cytolytic activity induced by a standard immunization with murine cytomegalovirus. Furthermore, DB induced a typical T-helper 1 (Th1)-dominated immune response in mice, as determined by cytokine and immunoglobulin G isotype analysis. Induction of humoral and cellular immune responses was achieved without the concomitant use of adjuvant. We thus propose that DB can serve as a basis for the future development of a recombinant nonreplicating vaccine against HCMV. Finally, such particles could be engineered for efficient delivery of antigens from other pathogens to the immune system.
用人巨细胞病毒（HCMV）感染成纤维细胞培养物会导致产生大量有缺陷的包膜颗粒，即致密体（DB）。这些无感染性的结构含有主要抗原决定簇，它们负责诱导针对HCMV的体液免疫和细胞免疫反应。我们检验了这样一个假设，即由于其独特的抗原和结构特性，致密体在无感染性病毒的情况下可诱导显著的免疫反应。用梯度纯化的致密体免疫小鼠，这些致密体要么未经处理，要么经过连续几轮超声处理和冻融以防止细胞进入。致密体诱导的中和抗体滴度与恢复期人血清中的水平相当。病毒中和抗体反应惊人地持久，初次免疫后12个月仍能检测到中和抗体。使用转染了人HLA - A2分子的小鼠来检测HCMV特异性主要组织相容性复合体I类限制性细胞溶解T细胞（CTL）反应。用致密体免疫可在无新生病毒蛋白合成的情况下导致高水平的HCMV特异性CTL。用致密体免疫的小鼠中的最大总细胞溶解活性几乎与用鼠巨细胞病毒标准免疫诱导的细胞溶解活性一样有效。此外，通过细胞因子和免疫球蛋白G同种型分析确定，致密体在小鼠中诱导了典型的以T辅助1（Th1）为主的免疫反应。在不使用佐剂的情况下实现了体液免疫和细胞免疫反应的诱导。因此，我们提出致密体可作为未来开发针对HCMV的重组非复制疫苗的基础。最后，这种颗粒可被设计用于将来自其他病原体的抗原有效递送至免疫系统。
