Discovering new host-pathogen interactions to develop antivirals and vaccine strategies against PRRSV

猪繁殖与呼吸综合征（PRRS）是猪的一种病毒性疾病，造成重大经济损失。该病的病原体是PRRS病毒（PRRSV），一种快速进化的小包膜阳性RNA病毒。改良活疫苗在交叉保护方面往往被证明是无效的，有些疫苗已被证明会引起传播性感染。因此，PRRS仍然对动物健康和福利产生重大影响，导致所有PRRSV感染猪的妊娠减少或丧失、仔猪死亡和生长率下降。PRRSV是宿主免疫反应的主要调节剂。这种病毒感染先天免疫应答细胞，特别是巨噬细胞和树突状细胞的某些亚群。PRRSV感染后，细胞因子分泌和先天宿主细胞反应被病毒感染主动下调，从而导致先天和适应性免疫反应的调节。I型干扰素（IFN）反应受到多种非结构蛋白和结构蛋白的积极干扰，目前尚不完全清楚(1)。PRRSV对免疫系统的干扰影响超出了PRRSV感染本身。由于缺乏免疫反应，与其他病原体的合并感染会增加。因此，了解PRRSV如何干扰宿主免疫系统并确定参与这一过程的病毒因子是很重要的。这将为我们提供合理减毒PRRSV的工具，以产生更有效和更安全的疫苗。病毒是细胞内的强制性寄生虫，利用细胞机制侵入和操纵宿主复制病毒粒子。因此，了解病毒与宿主的相互作用对于设计抗病毒策略至关重要，例如抗病毒药物、疫苗、遗传选择或基因组编辑靶点。fda批准的药物都针对细胞通路，因此是一个理想的起点，用于原代巨噬细胞，以识别PRRSV感染期间利用的宿主机制。被确定为抗病毒药物的药物不仅可以进一步研究宿主-病原体相互作用，而且这些药物和类似的化合物可能被开发用于抗病毒治疗。在这个项目中，我们的目标是确定参与IFN反应下调的病毒基因，并设计合理的疫苗衰减策略。我们还将研究干扰素诱导鸟苷酸结合蛋白（GBP）家族中已知抗病毒基因的作用，该家族的多态性最近被证明在抗PRRSV感染方面发挥作用(2)。与Jason Mercer博士（MRC LMCB, London）的实验室合作，将通过fda批准的药物筛选来研究原代肺泡巨噬细胞中的宿主-病原体相互作用机制，并对已确定的化合物进行跟踪研究，以确定它们在病毒复制周期中的作用。这个为期4年的CASE学生项目将在生物学的各个领域提供优秀的培训，涵盖基因组学和遗传学、系统生物学、病毒学、细胞生物学、先天免疫学、生物化学和分子生物学等方面。成功的候选人将学习和应用各种各样的技术，例如病毒学技术（滴定，纯化），原代细胞和永生化细胞系的细胞培养，荧光激活细胞分选，western blotting，荧光显微镜等等。References1。孙勇，韩明，金翀，刘东。2012。干扰素介导的先天免疫与猪繁殖与呼吸综合征病毒的相互作用。病毒4:424 - 446.2。张建军，张建军，张建军。2017。苗猪对猪繁殖与呼吸综合征反应的宿主遗传学。兽医微生物学209:107-113。

Porcine Reproductive and Respiratory Syndrome (PRRS) is a viral disease of pigs leading to major economic losses. The causative agent of the disease is PRRS virus (PRRSV), a rapidly evolving, small, enveloped positive-sense RNA virus. Modified live vaccines often prove ineffective in cross-protection and some have been shown to cause spreading infections. Thus, PRRS still has major impacts on animal health and welfare, resulting in reduction or loss of pregnancies, death in young piglets, and decreased growth rates in all PRRSV infected pigs. PRRSV is a master modulator of the host immune response. The virus infects cells of the innate immune response, specifically certain subsets of macrophages and dendritic cells. Upon PRRSV infection cytokine secretion and the innate host cell response are actively downregulated by the viral infection resulting in modulation of both the innate and adaptive immune response. The type I interferon (IFN) response is actively interfered with by multiple non-structural and structural proteins and is far from being fully understood (1). The interference of PRRSV with the immune system has impacts beyond PRRSV infection itself. Co-infections with other pathogens are enhanced due to the lack of immune response. Therefore, it is important to understand how PRRSV interferes with the host immune system and to identify viral factors involved in this process. This will give us tools to rationally attenuate PRRSV to generate more effective and safer vaccines.Viruses are mandatory intracellular parasites and use the cellular machinery to invade and manipulate the host to replicate the virions. Therefore, understanding the virus-host interaction is crucial to devising antiviral strategies, such as antiviral drugs, vaccines, genetic selection, or genome editing targets. FDA-approved drugs all target cellular pathways and are therefore an ideal starting point to use on primary macrophage cells to identify host machinery exploited by PRRSV during infection. Not only will the drugs identified as being antiviral allow further investigation into the host-pathogen interaction but the drugs and similar compounds may be developed for use in antiviral treatment.In this project we aim to identify viral genes involved in the downregulation of the IFN response and devise rational attenuation strategies for vaccines. We will also investigate the role of known antiviral genes of the interferon-inducible guanylate-binding protein (GBP) family, polymorphisms in which recently were shown to play a role in resilience towards PRRSV infection (2). Host-pathogen interaction mechanisms in primary alveolar macrophage cells will be investigated by performing an FDA-approved drug screen in collaboration with the lab of Dr Jason Mercer (MRC LMCB, London) and identified compounds followed up to identify their role in the viral replication cycle. This 4-year CASE studentship will provide excellent training in a variety of fields of biology, covering aspects of genomics and genetics, systems biology, virology, cell biology, innate immunology, biochemistry, and molecular biology. The successful candidate will learn and apply a wide variety of techniques, e.g. virological techniques (titration, purification), cell culture of primary cells and immortalized cell lines, fluorescence-activated cell sorting, western blotting, fluorescence microscopy, and many more. References1. Sun Y, Han M, Kim C, Calvert JG, Yoo D. 2012. Interplay between interferon-mediated innate immunity and porcine reproductive and respiratory syndrome virus. Viruses 4:424-446.2. Dekkers J, Rowland RRR, Lunney JK, Plastow G. 2017. Host genetics of response to porcine reproductive and respiratory syndrome in nursery pigs. Veterinary microbiology 209:107-113.