A vaccine for genital herpes that achieves sterilizing immunity

摘要 预防生殖器疱疹的疫苗是高度公共卫生优先事项。表现良好的疱疹疫苗 在啮齿动物身上并没有保护人类；因此，需要新的方法。我们提出以下建议： 1)在动物模型中设置比以前更高的疫苗效力门槛。一个国家的“黄金标准” 疱疹疫苗是一种无菌免疫，定义为没有生殖器损害和亚临床证据 感染后第2天阴道滴度为阴性的感染，没有复发的阴道发作 背根神经节有HSV-2 DNA脱落，无HSV-2 DNA脱落。之前的疱疹候选疫苗有 防止了死亡并减少了生殖器损害，但没有一种方法能接近于通过 预防亚临床感染。我们已经将95%的动物的绝育免疫作为我们的目标。 2)制定策略，防止病毒逃避疫苗诱导的免疫。抗体与 为我们绝大多数有效的人类疫苗提供保护。单纯疱疹病毒编码糖蛋白C(GC)和E(GE) 它们是免疫逃逸分子，能抑制抗体和补体。我们的疫苗战略建立在 由GD提供的免疫力，并阻止病毒逃避抗体和补体攻击的能力。 3)改进抗原递送方式。我们使用核苷修饰的信使核糖核酸，而不是亚单位蛋白质 免疫原。我们报告了在小鼠身上使用含有修饰的mRNA的三价疫苗的初步结果 编码糖蛋白C、D和E(GC2/GD2/gE2)的脂类纳米粒。修饰后的mRNA 用1-甲基假尿苷残基取代尿苷核苷。我们在63年实现了无菌免疫/ 小鼠(98%)与亚单位抗原免疫的14/20(70%)相比。我们将延长这一令人兴奋的时间 结果包括对幼稚和HSV-1阳性豚鼠的研究，作为对疫苗有效性的更严格测试， 评估雄性和雌性动物，并确定对生殖器HSV-1的交叉保护。 4)确定实现灭菌免疫所需的免疫相关因素。我们将评估血清中的ELISA值， 中和效价，阻止细胞间传播的抗体，阻止GC和GE免疫逃避的抗体， 抗体依赖的细胞毒性滴度，粘膜ELISA和中和抗体作为免疫 保护的关联性。这些研究将有助于为未来的人体试验建立免疫原性目标。 5)确定mRNA免疫是否产生针对关键表位的抗体。关键表位 包括中和病毒GC和GD，抑制补体和抗体的GC和GE，以及GD和 通用电气参与了细胞间的传播。我们将使用一种新型的高通量生物传感器平台来确定 免疫会产生针对这些关键表位的抗体。测定表位特异性抗体反应 将确定免疫原性方面的差距，并指导我们对这些表位进行修改，以加强疫苗保护。 这四个实验室拥有联合开发生殖器疱疹疫苗的专业知识，可以实现绝育 动物的免疫力，随后在人类的免疫力。

Abstract A vaccine for prevention of genital herpes is a high public health priority. Herpes vaccines that performed well in rodents have not protected humans; therefore, novel approaches are needed. We propose the following: 1) Set a much higher bar for vaccine efficacy in animal models than used previously. The “gold standard” for a herpes vaccine is sterilizing immunity, defined as no genital lesions and no evidence of subclinical infection as measured by negative day 2 vaginal titers post-infection, no recurrent episodes of vaginal shedding of HSV-2 DNA and no HSV-2 DNA in dorsal root ganglia. Prior herpes candidate vaccines have prevented death and reduced genital lesions, but none has come close to achieving sterilizing immunity by preventing subclinical infection. We have set sterilizing immunity in >95% of animals as our goal. 2) Devise strategies to prevent the virus from evading vaccine-induced immunity. Antibodies correlate with protection for the vast majority of our effective human vaccines. HSV encodes glycoproteins C (gC) and E (gE) that are immune evasion molecules that inhibit antibody and complement. Our vaccine strategy builds upon the immunity provided by gD and blocks the ability of the virus to evade antibody and complement attack. 3) Modify antigen delivery methods. We use nucleoside-modified mRNA, rather than subunit proteins as immunogens. We report preliminary results in mice using a trivalent vaccine that contains modified mRNA encoding glycoproteins C, D and E (gC2/gD2/gE2) administered in lipid nanoparticles. The modified mRNA replaces uridine nucleosides with 1-methylpseudouridine residues. We achieve sterilizing immunity in 63/64 (98%) mice compared with 14/20 (70%) immunized with subunit antigens. We will extend this exciting result to include studies in naïve and HSV-1 positive guinea pigs as a more stringent test of vaccine efficacy, evaluate male and female animals, and determine cross-protection against genital HSV-1. 4) Define the immune correlates required to achieve sterilizing immunity. We will assess serum ELISA titers, neutralizing titers, antibodies that block cell-to-cell spread, antibodies that block gC and gE immune evasion, antibody-dependent cellular cytotoxicity titers, and mucosal ELISA and neutralizing antibodies as immune correlates of protection. These studies will help establish immunogenicity targets for future human trials. 5) Determine whether mRNA immunization produces antibodies to crucial epitopes. The crucial epitopes include those on gC and gD that neutralize virus, gC and gE that inhibit complement and antibody, and gD and gE involved in cell-to-cell spread. We will use a novel high throughput biosensor platform to determine whether immunization produces antibodies to these crucial epitopes. Measuring epitope specific antibody responses will identify gaps in immunogenicity and guide us on those epitopes to modify to enhance vaccine protection. The four labs have the combined expertise to develop a genital herpes vaccine that achieves sterilizing immunity in animals and subsequently in humans.