Novel Strategy for Animal Model Testing of HCMV Vaccines

描述（由申请人提供）：预防先天性人巨细胞病毒（HCMV）感染的疫苗是一项紧迫的公共卫生优先事项。基于纯化重组糖蛋白B （gB）的亚单位疫苗，在中国仓鼠卵巢（CHO）细胞中表达，目前正在临床试验中进行测试。这种疫苗的基本原理是基于在人类恢复期血清中发现的大多数病毒中和抗体对这种蛋白质具有特异性的观察。在豚鼠先天性巨细胞病毒感染模型中，纯化的重组形式的豚鼠巨细胞病毒（GPCMV） gB对感染和疾病具有保护作用，这一观察结果证实了HCMV gB疫苗可能对先天性感染有效的假设。然而，不幸的是，迄今为止还不可能在动物模型（如GPCMV模型）中测试HCMV gB疫苗的效力。这是因为，尽管人类gB疫苗在豚鼠中具有免疫原性，但由于各自的cmv具有严格的物种特异性，因此不可能在豚鼠中进行HCMV病毒攻击实验。然而，最近，基于在大肠杆菌中成功地将巨细胞病毒基因组作为细菌人工染色体（BACs）的病毒诱变策略的发展，代表了在产生重组嵌合病毒方面的重大进展。现在，通过将异源HCMV基因靶向插入病毒基因组，产生具有复制能力的gpcmv是可行的。在此背景下，本研究旨在验证以下假设：1)在GPCMV基因组中表达HCMV gB蛋白的新型重组“swap”突变体将在体内保持复制能力和引起先天性感染和疾病的能力；2)纯化的重组HCMV gB，与MF59佐剂一起使用，将保护“人源化”病毒攻击的怀孕动物免受先天性感染和疾病。这些研究将代表人类巨细胞病毒亚单位疫苗在先天性巨细胞病毒感染的小动物模型中的首次有效性试验。

DESCRIPTION (provided by applicant): A vaccine for prevention of congenital infection with human cytomegalovirus (HCMV) is an urgent public health priority. A subunit vaccine based on purified recombinant glycoprotein B (gB), expressed in Chinese hamster ovary (CHO) cells, is currently being tested in clinical trials. The rationale for this vaccine is based on observations that the majority of virus-neutralizing antibodies found in human convalescent sera are specific for this protein. The observation that purified, recombinant forms of guinea pig cytomegalovirus (GPCMV) gB are protective against infection and disease in the guinea pig model of congenital CMV infection lends credence to the hypothesis that HCMV gB vaccines might be efficacious against congenital infection. However, to date it has unfortunately been impossible to test the efficacy of the HCMV gB vaccine in an animal model, such as the GPCMV model. This is because the strict species-specificity of the respective CMVs makes it impossible to perform HCMV viral challenge experiments in guinea pigs, even though the human gB vaccine is immunogenic in these animals. Recently, however, the development of viral mutagenesis strategies based on the successful doing of CMV genomes as bacterial artificial chromosomes (BACs) in E. coli has represented a major advance in generating recombinant, chimeric viruses. It is now feasible to generate replication-competent GPCMVs with targeted insertions of heterologous HCMV genes into the viral genome. Against this backdrop, this proposal seeks to test the hypotheses that: 1) a novel, recombinant 'swap' mutant, expressing the HCMV gB protein in the context of the GPCMV genome, will retain replication competence and the ability to cause congenital infection and disease in vivo; and, 2) that purified, recombinant HCMV gB, administered with MF59 adjuvant, will protect against congenital infection and disease in pregnant animals challenged with the 'humanized' virus. These studies will represent the first efficacy test of a human CMV subunit vaccine in a small animal model of congenital CMV infection.