tissue tropism of coronavirus

冠状病毒的组织向性

• 批准号: 10692256
• 负责人: Yasmine Belkaid
• 金额: $ 2.65万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10692256
• 关键词: Acetates; Acute; Adipose tissue; Age; Ampicillin; Antibiotics; Binding; Bladder; Brain; Butyrates; CEACAM1a; Colon; Confocal Microscopy; Coronavirus; Data; Diet; Dietary Fiber; Distal; Duodenum; Enteral; Epithelial; Esophagus; Esterase Gene; Family; Fermentation; Fiber; Food; Gastrointestinal tract structure; Genes; Germ-Free; Goals; Greater sac of peritoneum; Home; Immunity; Infection; Intestines; Intranasal Administration; Kidney; Laboratory mice; Liver; Lung; Mammalian Cell; Mammalian Oviducts; Mesentery; Modeling; Mucous Membrane; Murine hepatitis virus; Mus; Neuroglia; Nutritional status; Oral; Organ; Ovary; Pancreas; Pathogenicity; Pathology; Peyer' s Patches; Play; Polysaccharides; Process; Propionates; Pulmonary Inflammation; RNA; RNA Viruses; Research Personnel; Respiratory Signs and Symptoms; Role; Salivary Glands; Sialic Acids; Site; Spleen; Starch; Stomach; Tissues; Tongue; Tropism; Upper respiratory tract; Viral; Virus; Volatile Fatty Acids; betacoronavirus; commensal bacteria; env Gene Products; genome sequencing; hemagglutinin esterase; human disease; jejunum; member; mesenteric lymph node; microbiome; microbiome composition; microbiota; neural; nutrition; particle; pathogen; prevent; receptor; tissue tropism; viral RNA; virus host interaction; virus tropism; whole genome

Murine hepatitis virus is a positive sense single-stranded RNA virus within the Coronaviridae family and Betacoronavirus genus. As a natural pathogen of laboratory mice, MHV isolates are highly diverse, and each isolate has a specific range of organ tropisms. Broadly, these viruses can be divided into two groups. The polytropic viruses, such as MHV-A59, can replicate in the upper respiratory tract and then disseminate to more distal organs, such as the liver or brain. In contrast, enterotropic viruses replicate in the gastrointestinal tract and are largely do not disseminate systemically. This diversity in tissue tropism is remarkable considering that every MHV strain appears to use the same receptor, CEACAM1a. This suggests that the ability of enterotropic MHV to infect the intestine is determined by host-virus interactions that prevent polytropic viruses. Therefore, we sought to understand the host and viral mechanisms that enable enterotropic MHV-Y to infect the gastrointestinal tract. After acquiring MHV-Y as an isolate, we first comprehensibly compared the tropism of oral MHV-Y to the polytropic MHV-A59. We found that MHV-Y could efficiently infect peyers patches, mesenteric lymph nodes and the colon, while MHV-A59 primarily was restricted, in lower titers, to the peyers patches and mLN. After oral inoculation, neither virus strain was able to efficiently infect other parts of the gastrointestinal tract, including the duodenum, jejunum and ileal epithelium, stomach, esophagus, salivary glands or tongue. Additionally, more distal tissues in the peritoneal cavity, including the liver, spleen, kidney, bladder, ovaries, fallopian tubes did not produce high epithelium, liver, spleen, pancreas, mesenteric adipose tissue, gonadal adipose tissue and kidneys. Additionally, neither virus appeared in other classic barrier sites such as the upper respiratory tract and lungs, or in neural tissues. As the commensal bacteria have historically been shown to play a role in colonic tropism of viruses, we assessed the role of the microbiome in tissue tropism of MHV-Y. Surprisingly, while viral RNA levels in the peyers patches and mLN were similar between control and ampicillin treated mice, no infectious virus was present in the colons of antibiotic treated mice. These findings were recapitulated when we infected mice that completely lack a microbiome, also known as germ free mice, also did not have infectious viral particles in their colon. Together, this suggests that the microbiome is critical to enable colonic infection. One of the major functions of the microbiome is to process food into metabolites that are then used by mammalian cells. A major class of metabolites used are the short chain fatty acids, such as acetate, propionate, and butyrate. Therefore, we assessed whether the microbiome enable colonic infection of MHV-Y. We found that ampicillin treated mice that had acetate delivered to the colon, either through gavage of acetylated starch or a diet that contained acetylated starch, had higher levels MHV-Y RNA in the colon than mice that were not delivered acetate colonically; these data suggest that acetate, and perhaps other SCFAs, in part control colonic titers of MHV-Y. SCFAs are produced largely from the fermentation of fiber by the microbiome. Therefore, we assessed whether dietary fiber enabled colonic infection. We found that MHV-Y was not able to infect the colons mice on a highly defined diet that did not contain fiber, but on was able to infect the colons of mice on high fiber diet. Whole genome sequencing MHV-Y revealed that in contrast to the non-enterotropic MHV strains, MHV-Y encodes both a functional hemagglutinin esterase (HE) and NS4 gene. The HE gene was particularly intriguing as this gene is an envelope protein that is known to bind and hydrolyze 4-O acetylated sialic acid, which has previously been demonstrated to be highly enriched in the colon. Confocal microscopy revealed that 4-O acetylated sialic acid was highly prevalent in the colon and expressed on the enteric glia within the mucosa. Interestingly, ampicillin treatment reduced levels of 4-O acetylated sialic acid in the colon, suggesting that the microbiota is necessary for maintaining this modified glycan. Taken together, a model is emerging where colonic tropism of enteric coronaviruses is controlled by the nutritional status and microbiome composition of mice. These metabolites are substrates for modified sialic acids that serve as attachment factors for the virus to bind and home to the colon.

鼠类肝炎病毒是冠状病毒家族和贝塔克罗纳病毒属的阳性呈阳性的单链RNA病毒。作为实验室小鼠的天然病原体，MHV分离株高度多样，每个分离株都有特定的器官向性范围。从广义上讲，这些病毒可以分为两组。多粒素病毒（例如MHV-A59）可以在上呼吸道中复制，然后传播到更远端器官，例如肝脏或脑。相反，肠道病毒在胃肠道中复制，并且在很大程度上不会全身传播。考虑到每个MHV菌株似乎都使用相同的受体CEACAM1A，组织对乳液中的这种多样性非常出色。这表明，肠性MHV感染肠道的能力取决于预防多热病毒的宿主病毒相互作用。因此，我们试图理解能够使肠型MHV-y感染胃肠道的宿主和病毒机制。 在获得MHV-Y作为分离株之后，我们首先将口服MHV-Y的对流与多粒素MHV-A59进行了比较。我们发现MHV-Y可以有效地感染Peyers斑块，肠系膜淋巴结和结肠，而MHV-A59主要限制在较低的滴度中，限制为Peyers斑块和MLN。口服接种后，两种病毒菌株都无法有效感染胃肠道的其他部位，包括十二指肠，空肠和宫颈上皮，胃，食管，唾液腺或舌头。此外，包括肝脏，脾脏，肾脏，膀胱，卵巢，输卵管在内的腹膜腔中更远端组织没有产生高上皮上皮，肝脏，脾脏，胰腺，肠系膜脂肪组织，性腺脂肪组织，性腺脂肪组织和肾脏。此外，病毒均未出现在其他经典的屏障部位，例如上呼吸道和肺部或神经组织。 由于历史上已显示出共生细菌在病毒的结肠潮流中发挥作用，因此我们评估了微生物组在MHV-Y组织端主中的作用。令人惊讶的是，虽然对照和氨苄西林处理的小鼠之间的PEYERS斑块和MLN中的病毒RNA水平相似，但在抗生素处理的小鼠的结肠中没有传染病。当我们感染完全缺乏微生物组（也称为无菌小鼠）的小鼠时，这些发现也被概括了，其结肠中也没有传染性病毒颗粒。总之，这表明微生物组对于实现结肠感染至关重要。 微生物组的主要功能之一是将食物加工成代谢物，然后由哺乳动物细胞使用。使用的主要代谢产物是短链脂肪酸，例如乙酸，丙酸酯和丁酸酯。因此，我们评估了微生物组是否能够引起MHV-Y的结肠感染。我们发现，氨苄青霉素处理的乙酸酯通过乙酰化淀粉的饲料或含有乙酰化淀粉的饮食的小鼠的MHV-Y RNA高于未殖民地盐酸盐的小鼠的MHV-Y RNA水平更高。这些数据表明，乙酸盐，甚至可能是其他SCFA，部分控制MHV-Y的结肠滴度。 SCFA在很大程度上是由微生物组对纤维发酵产生的。因此，我们评估了饮食纤维是否启用了结肠感染。我们发现，MHV-y无法以高度定义的不含纤维的饮食感染结肠小鼠，但在高纤维饮食中能够感染小鼠的结肠。 整个基因组测序MHV-Y表明，与非输入的MHV菌株相比，MHV-Y编码功能性黑凝集素酯酶（HE）和NS4基因。 He基因特别有趣，因为该基因是一种包膜蛋白，已知可以结合和水解4-O乙酰化的唾液酸，以前已证明该乳酸在结肠中高度富集。共聚焦显微镜表明，4-O乙酰化的唾液酸在结肠中高度流行，并在粘膜内的肠神经胶质上表达。有趣的是，氨苄青霉素治疗降低了结肠中4-O乙酰化的唾液酸的水平，这表明微生物群对于维持这种改良的聚糖是必要的。 综上所述，一个模型正在出现，其中肠道冠状病毒的结肠向嗜性受小鼠的营养状态和微生物组组成控制。这些代谢产物是修饰的唾液酸的底物，它们是病毒结合并与结肠结合的附着因子。