Deciphering the role of telomeric repeats encoded by Marek’s disease virus-vaccines in latency, integration and protection against disease

破译马立克氏病病毒疫苗编码的端粒重复序列在潜伏、整合和预防疾病中的作用

• 批准号: 525166869
• 负责人: Professor Dr. Benedikt Bertold Kaufer, Ph.D.
• 金额: --
• 依托单位: Institut für Virologie (WE05)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/525166869?language=en
• 关键词: Deciphering; role; telomeric; repeats; encoded

Marek’s disease virus (MDV) is a highly oncogenic alphaherpesvirus that causes immunosuppression, neurological symptoms and T cell lymphomas in chickens. Vaccines are crucial to protect billions of chickens against this deadly virus every year. Three different live vaccine viruses, herpesvirus of turkey (HVT), gallid herpesvirus 3 (GaHV-3, aka. SB-1) and the attenuated MDV strain CVI988, are used to protect against MDV and also serve as vaccine vectors against other pathogens; however, hardly anything is known about the biology of these viruses. Our preliminary data revealed that theses vaccine viruses integrate into the ends of host chromosomes containing the host telomeres in latently infected cells. Intriguingly, these MDV vaccine viruses harbor telomeric repeat arrays (TMRs) identical to the host telomeres at both ends of their genomes, which could facilitate integration. We therefore hypothesize that the TMRs facilitate integration of the vaccine viruses into host telomeres, and thereby contribute to vaccine latency and vaccine protection due to prolonged exposure with the virus. We will address this hypothesis with three specific aims. Specifically, we will 1) determine the role of the TMRs in vaccine replication and integration in vitro, 2) elucidate the role of the TMRs in the establishment of vaccine latency and reactivation in the host and 3) investigate if integration and persistence of the vaccine viruses contribute to the protection against MDV. To achieve aim 1, we will generate recombinant vaccine viruses (HVT, SB-1 and CVI988) lacking TMRs (∆TMR) to assess the role of these viral telomere sequences in virus replication and integration using our recently established in vitro integration assay. Further, we will investigate the integration sites of wild type and ∆TMR vaccine viruses using our novel Bionano imaging approach. To address aim 2, we will infect chickens with wild type and ∆TMR vaccines (HVT-∆TMR already available) and monitor virus replication, dissemination and shedding into the environment over time. Beyond that, we will investigate latency and reactivation in the presence and absence of the TMRs in the lymphoid organs. In aim 3, we will vaccinate chickens with wild type and ∆TMR vaccines (HVT-∆TMR already available) and challenge them with a very virulent MDV strain. We will assess the efficacy of these vaccines in suppressing MDV replication and shedding, and determine if prolonged persistence facilitated by vaccine virus integration contributes to vaccine-protection against MDV. Taken together, this project will provide crucial insights into the biology of these important veterinary vaccine viruses including the roles of the TMRs in vaccine integration, latency and vaccine protection against this deadly pathogen.

马立克氏病病毒（MDV）是一种高度致癌的α疱疹病毒，可引起鸡的免疫抑制、神经系统症状和T细胞淋巴瘤。疫苗对于每年保护数十亿只鸡免受这种致命病毒的侵害至关重要。三种不同的活疫苗病毒，火鸡疱疹病毒（HVT），鸡疱疹病毒3（GaHV-3，又名。SB-1）和减毒MDV毒株CVI 988，用于保护免受MDV的侵害，也用作针对其他病原体的疫苗载体;然而，对这些病毒的生物学几乎一无所知。我们的初步数据表明，这些疫苗病毒整合到宿主染色体的末端，含有宿主端粒在潜伏感染细胞。有趣的是，这些MDV疫苗病毒在其基因组的两端具有与宿主端粒相同的端粒重复序列（TMR），这可能有助于整合。因此，我们假设TMR促进疫苗病毒整合到宿主端粒中，从而有助于疫苗潜伏期和由于长期暴露于病毒而产生的疫苗保护。我们将以三个具体目标来讨论这一假设。具体而言，我们将1）确定TMR在疫苗体外复制和整合中的作用，2）阐明TMR在建立疫苗潜伏期和宿主再活化中的作用，3）研究疫苗病毒的整合和持续存在是否有助于对MDV的保护。为了实现目标1，我们将产生缺乏TMR的重组疫苗病毒（HVT、SB-1和CVI 988）（TMPTMR），以使用我们最近建立的体外整合测定来评估这些病毒端粒序列在病毒复制和整合中的作用。此外，我们将使用我们的新型Bionano成像方法研究野生型和ESTTMR疫苗病毒的整合位点。为了实现目标2，我们将用野生型和HVT-10 TMR疫苗（HVT-10 TMR已经可用）感染鸡，并随着时间的推移监测病毒复制、传播和脱落到环境中。除此之外，我们将研究淋巴器官中存在和不存在TMR的潜伏期和再激活。在目标3中，我们将用野生型和HVT TMR疫苗（HVT-HVT TMR已经可用）接种鸡，并用极强毒MDV毒株攻击它们。我们将评估这些疫苗在抑制MDV复制和散毒方面的有效性，并确定疫苗病毒整合促进的持久性是否有助于疫苗对MDV的保护。总之，该项目将为这些重要的兽医疫苗病毒的生物学提供重要的见解，包括TMR在疫苗整合，潜伏期和疫苗保护中的作用。