Development of an effective DISC vaccine strategy against congenital CMV

描述（由申请人提供）：由于存在先天性感染的风险，巨细胞病毒（CMV）疫苗的开发是一项重要的公共卫生优先事项。临床致病性巨细胞病毒株与实验室适应株的不同之处在于，它们保留了感染上皮细胞和内皮细胞的能力。基于胎盘的结构，内皮细胞可能是病毒通过胎盘向胎儿转移的一个潜在的重要部位。病毒进入内皮细胞/内皮细胞的机制与进入成纤维细胞的gB途径不同，因为它需要病毒蛋白gH/gL/UL128-131形成内吞复合物才能使病毒进入细胞。豚鼠是唯一一种允许使用种特异性豚鼠CMV （GPCMV）研究先天性巨细胞病毒的小动物模型。我们最近研究了一种复制受损的GPCMV活疫苗的使用，这种疫苗需要一种补充细胞系来生产感染性病毒。这种失活的传染性单循环（DISC）疫苗策略产生的病毒可以感染细胞表达一系列病毒抗原并诱导免疫反应，但不产生感染性病毒。这种疫苗策略在豚鼠中具有高度的免疫原性，对重要的病毒抗原产生抗体和T细胞反应。然而，我们最初的DISC疫苗缺乏新发现的与人类CMV UL128-131 （GP128-131）同源的基因座。因此，这种疫苗策略缺乏对潜在的GPCMV内吞复合物产生免疫应答的能力。在本申请中，我们建议确定GPCMV进入内皮细胞的条件，并进一步开发第二代DISC疫苗，该疫苗携带必要的抗原，以诱导有效的中和免疫反应，抵抗内皮细胞的病毒感染。作为第二代DISC疫苗策略的一部分，该病毒将进一步减毒，以增加免疫原性，并通过敲除pp71同源物来降低病毒建立潜伏期的能力。将研究第二代DISC疫苗预防先天性GPCMV的能力，并将其与该模型中先前研究的重组gB疫苗策略进行比较，以确定其有效性。

DESCRIPTION (provided by applicant: Development of a cytomegalovirus (CMV) vaccine is a major public health priority due to the risk of congenital infection. Pathogenic clinical strains o CMV differ from lab adapted strains in that they retain the ability to infect epithelial and endothelial cells. Based on the structure of the placenta endothelial cells could be a potentially important site for initiation of virus transfer across the placenta to the fetus. The mechanism of virus entry into epi/endothelial cells is different from the gB pathway of entry into fibroblast cels as it requires viral proteins gH/gL/UL128-131 forming an endocytic complex to enable viral cell entry. The guinea pig is the only small animal model that allows the study of congenital CMV by using species specific guinea pig CMV (GPCMV). We recently investigated the use of a replication-impaired live GPCMV vaccine that requires a complementing cell line for production of infectious virus. This disabled infectious single cycle (DISC) vaccine strategy results in a virs that can infect cells to express an array of viral antigens and induce an immune response but does not produce infectious virus. This vaccine strategy was highly immunogenic in guinea pigs producing antibody and T cell responses to important viral antigens. However, our original DISC vaccine lacked a newly identified homolog locus to human CMV UL128-131 (GP128-131). Consequently, this vaccine strategy lacks the ability to generate an immune response against a potential GPCMV endocytic complex. In this application we propose to define requirements for GPCMV entry into endothelial cells and additionally develop a 2nd generation DISC vaccine carrying the essential antigens necessary to induce an effective neutralizing immune response against viral infection of epi/endothelial cells. As part of this 2nd generation DISC vaccine strategy the virus will be further attenuated to increase immunogenicity and decrease the ability of the virus to establish latency by the knockout of the pp71 homolog. The ability of second generation DISC vaccines to protect against congenital GPCMV will be investigated and efficacy determined by comparing it with a recombinant gB vaccine strategy previously investigated in this model. PUBLIC HEALTH RELEVANCE: Cytomegalovirus (CMV) is a ubiquitous pathogen that causes significant mortality and morbidity in immunocompromised populations including transplant and AIDS patients and the fetus in utero. Congenital CMV infection causes mental retardation and deafness in surviving newborn. CMV is the most common AIDS related secondary infection. There is no vaccine to CMV. Although current antivirals are available for transplant and AIDS patients these result in the emergence of resistant strains that cause disease. Additionally, antiviral drug toxic side effects preclude their use in the prevention of congenital CMV.