Development of an effective genital herpes vaccine

描述（由申请人提供）：30年来，一直在寻找一种有效的疫苗来预防由单纯疱疹病毒2型（HSV-2）引起的生殖器疱疹。大多数研究集中在非复制型HSV-2疫苗剂如糖蛋白D亚单位或复制缺陷型HSV-2病毒的开发上。这些办法值得考虑。然而，目前尚不清楚非复制型HSV-2疫苗是否能引发所寻求的针对生殖器疱疹的终身免疫力。在没有有效疫苗的情况下，每年又有1000万至2000万人感染HSV-2。考虑到问题的范围，也许是时候考虑第二种可能性了：一种活的、复制的HSV-2疫苗株可能更有效。我们在控制人类病毒性疾病方面取得的大多数成功都是基于活的、复制的病毒。活牛痘病毒（最初的疫苗）被用来结束天花的流行。小儿麻痹症、腮腺炎、麻疹、风疹和水痘可以通过儿童疫苗来预防，这些疫苗含有自然界中存在的活的、复制的病毒，但其致病潜力被减弱。这是我们最成功的疫苗接种方式，尚未充分考虑其控制生殖器疱疹的潜力。在很大程度上，这是由于错误地认为HSV-2活疫苗株是危险的。私家侦探已发表的研究和初步数据表明，基因工程结合HSV生物学的现有知识，可用于获得安全且具有免疫原性的活的、复制的HSV-1和HSV-2病毒疫苗。原则上，HSV的减毒很容易实现，因为75个HSV基因中的约30个对于病毒复制不是必需的。这些基因中的许多基因，如ICP 0基因，是HSV抵抗宿主免疫反应抑制所必需的。私家侦探已经研究干扰素敏感的HSV-1 ICP 0病毒10年。ICP 0基因的破坏使HSV-1和HSV-2对干扰素-1/2的抑制高度敏感，在动物中无毒，但这些病毒可作为强有力的免疫原。用活的复制型HSV-1 ICP 0病毒免疫的小鼠对1000倍LD 50剂量的HSV-1（McKrae株）或HSV-2（MS株）的致死攻击具有免疫力。同样，在免疫部位HSV-2 ICP 0病毒复制的小鼠对HSV-2 MS致死性攻击具有免疫力。尚未进行系统性努力以开发可在免疫部位建立不明显感染的活的且适当减毒的HSV-2病毒。私家侦探的数据表明，只有当病毒在宿主中复制时，HSV-1或HSV-2的全部免疫原性潜力才能实现。如果这一假设是正确的，那么活的复制型HSV疫苗株可能比迄今为止认为的任何非复制型HSV疫苗都更具保护性。需要两年的R21资金来验证这一假设，并开始开发HSV-2 ICP 0病毒，如果HSV-2活疫苗株被证明安全有效地保护小鼠、豚鼠、兔子和仓鼠免受生殖器疱疹的感染，这些病毒以后可能用于人体临床试验。公共卫生相关性：干扰素敏感性单纯疱疹病毒-2（HSV-2）ICP 0-病毒拟定作为一种活的复制型HSV-2疫苗株。这种HSV-2活疫苗株可能能够预防生殖器疱疹的传播，生殖器疱疹是一种目前困扰全球约5000万人的疾病。本文提出的工作将检验一种假设，即相对于30年来一直是研究焦点的非复制型HSV-2疫苗，活的复制型HSV-2 ICP 0-病毒提供针对外源性HSV-2感染的上级保护。预计这些研究将产生一种新的HSV-2 ICP 0活疫苗株，从而保证其进入人体临床试验。

DESCRIPTION (provided by applicant): For 30 years, an effective vaccine has been sought to prevent genital herpes caused by herpes simplex virus 2 (HSV-2). Most of the research has focused on the development of non-replicating HSV-2 vaccine agents such as the glycoprotein D subunit or replication-defective HSV-2 viruses. Such approaches merit consideration. However, it is unclear that non-replicating HSV-2 vaccines elicit the type of life-long immunity against genital herpes that is sought. For each year that elapses without an effective vaccine, another 10 to 20 million people contract HSV-2 infections. Given the scope of the problem, perhaps it is time to consider a second possibility: a live, replicating HSV-2 vaccine strain may be more effective. Most of our successes in controlling viral disease in the human population have been based upon live, replicating viruses. Live vaccinia virus (the original vaccine) was used to end smallpox epidemics. Poliomyelitis, mumps, measles, rubella, and chickenpox are prevented with childhood vaccines that contain live, replicating viruses that occur in nature, but are attenuated in their disease-causing potential. This, our most successful vaccination modality, has not been adequately considered for its potential to control genital herpes. In large part, this is due to the misconception that a live HSV-2 vaccine strain would be dangerous. The P.I.'s published studies and preliminary data establish that genetic engineering combined with current knowledge of HSV biology may be applied to derive live, replicating HSV-1 and HSV-2 viral vaccines that are safe and immunogenic. In principle, attenuation of HSV is readily achieved because ~30 of 75 HSV genes are not essential for viral replication. Many of these genes, such as the ICP0 gene, are required for HSV to resist repression by the host immune response. The P.I. has worked with interferon-sensitive HSV-1 ICP0- viruses for 10 years. Disruption of the ICP0 gene renders HSV-1 and HSV-2 hypersensitive to repression by interferon-1/2, avirulent in animals, and yet these viruses may serve as powerful immunogens. Mice immunized with a live, replicating HSV-1 ICP0- virus are immune to lethal challenge with 1000 times the LD50 dose of HSV-1 (McKrae strain) or HSV-2 (MS strain). Likewise, mice in which an HSV-2 ICP0- virus replicates at the site of immunization are immune to lethal challenge with HSV-2 MS. A systematic effort has not been made to develop a live and appropriately attenuated HSV-2 virus that may establish an inapparent infection at the site of immunization. The P.I.'s data indicate that HSV-1 or HSV-2's full immunogenic potential is only realized when viral replication occurs in the host. If this hypothesis is correct, then live, replicating HSV vaccine strains may be far more protective than any non-replicating HSV vaccine considered to date. Two years of R21 funding is requested to test this hypothesis, and to begin developing HSV-2 ICP0- viruses that may later be used in human clinical trials if a live HSV-2 vaccine strain proves to be safe and effective in protecting mice, guinea pigs, rabbits, and hamsters against genital herpes. PUBLIC HEALTH RELEVANCE: Interferon-sensitive herpes simplex virus-2 (HSV-2) ICP0- viruses are proposed as a live, replicating HSV-2 vaccine strain. Such live HSV-2 vaccine strains may be capable of preventing the spread of genital herpes, a disease that currently afflicts ~50 million people worldwide. The work proposed herein will test a hypothesis that live, replicating HSV-2 ICP0- viruses provide superior protection against exogenous HSV-2 infections relative to non-replicating HSV-2 vaccines that have been the focus of research for 30 years. It is anticipated that a new live HSV-2 ICP0- vaccine strain will emerge from these studies that warrants advancement to human clinical trials.