Fusion-Related Host Proteins Are Actively Regulated by NA during Influenza Infection as Revealed by Quantitative Proteomics Analysis

Three recombinant influenza A viruses with different neuraminidases (NAs) in the background of A/PR/8/34 (PR8), named rPR8-H5N1NA, rPR8-H9N2NA, and rPR8-H1N1NA, derived from H5N1, H9N2, H1N1 (swine) viruses, respectively, were constructed. We performed a quantitative proteomics analysis to investigate differential protein expression in Madin-Darby canine kidney (MDCK) cells infected with recombinant and wild-type influenza viruses to determine whether NA replacement would alter host cell gene expression. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-TOF MS) and two-dimensional gel electrophoresis (2-DE), we identified 12 up-regulated and 49 down-regulated protein spots, including cytoskeletal proteins, molecular biosynthesis proteins, ubiquitin-proteasome pathway proteins, and heat shock proteins. The most significant changes in infected cells were observed for molecular biosynthesis proteins. We found more differentially expressed protein spots in cells infected with rPR8-H5N1NA or rPR8-H9N2NA viruses than cells infected with wild-type virus. Many of those proteins are postulated to be involved in cell-cell fusion, but the full mechanism remains to be explored. Meanwhile, our data demonstrate that the wild-type virus has evolutionary advantages over recombinant viruses.     

siRNA Screen Identifies Trafficking Host Factors that Modulate Alphavirus Infection

Little is known about the repertoire of cellular factors involved in the replication of pathogenic alphaviruses. To uncover molecular regulators of alphavirus infection, and to identify candidate drug targets, we performed a high-content imaging-based siRNA screen. We revealed an actin-remodeling pathway involving Rac1, PIP5K1- α, and Arp3, as essential for infection by pathogenic alphaviruses. Infection causes cellular actin rearrangements into large bundles of actin filaments termed actin foci. Actin foci are generated late in infection concomitantly with alphavirus envelope (E2) expression and are dependent on the activities of Rac1 and Arp3. E2 associates with actin in alphavirus-infected cells and co-localizes with Rac1–PIP5K1-α along actin filaments in the context of actin foci. Finally, Rac1, Arp3, and actin polymerization inhibitors interfere with E2 trafficking from the trans-Golgi network to the cell surface, suggesting a plausible model in which transport of E2 to the cell surface is mediated via Rac1- and Arp3-dependent actin remodeling.     

敲除pckA基因的结核杆菌引起的免疫反应的研究

研究结核杆菌pckA基因编码的磷酸烯醇型丙酮酸羧激酶(PEPCK)诱导机体产生的保护性免疫反应。用敲除pckA基因的牛结核杆菌BCG和野生型BCG分别感染小鼠,取肝、肺、脾进行病理分析,并进行脾细胞培养,检测CD4 、CD4 /CD8 、细胞因子IFNI-γI、L-12和TNF等。用敲除pckA基因的BCG感染的小鼠比野生型BCG感染的小鼠体内产生的结核结节少且不典型,炎性程度低。野生型BCG感染的小鼠脾脏内的CD4 T细胞和CD4 /CD8 、细胞因子IFN-γ、IL-12、TNF均明显高于敲除pckA基因BCG感染的小鼠。pckA基因为结核杆菌生长所必需,其编码产物PEPCK能够刺激机体产生免疫反应,是一种很好的疫苗候选分子。     

Genome-Wide RNAi Screen Identifies Novel Host Proteins Required for Alphavirus Entry

The enveloped alphaviruses include important and emerging human pathogens such as Chikungunya virus and Eastern equine encephalitis virus. Alphaviruses enter cells by clathrin-mediated endocytosis, and exit by budding from the plasma membrane. While there has been considerable progress in defining the structure and function of the viral proteins, relatively little is known about the host factors involved in alphavirus infection. We used a genome-wide siRNA screen to identify host factors that promote or inhibit alphavirus infection in human cells. Fuzzy homologue (FUZ), a protein with reported roles in planar cell polarity and cilia biogenesis, was required for the clathrin-dependent internalization of both alphaviruses and the classical endocytic ligand transferrin. The tetraspanin membrane protein TSPAN9 was critical for the efficient fusion of low pH-triggered virus with the endosome membrane. FUZ and TSPAN9 were broadly required for infection by the alphaviruses Sindbis virus, Semliki Forest virus, and Chikungunya virus, but were not required by the structurally-related flavivirus Dengue virus. Our results highlight the unanticipated functions of FUZ and TSPAN9 in distinct steps of alphavirus entry and suggest novel host proteins that may serve as targets for antiviral therapy.     

Affinity Proteomics Exploration of Melanoma Identifies Proteins in Serum with Associations to T-Stage and Recurrence

BACKGROUND: Blood-based proteomic profiling may aid and expand our understanding of diseases and their different phenotypes. The aim of the presented study was to profile serum samples from patients with malignant melanoma using affinity proteomic assays to describe proteins in the blood stream that are associated to stage or recurrence of melanoma. MATERIAL AND METHODS: Multiplexed protein analysis was conducted using antibody suspension bead arrays. A total of 232 antibodies against 132 proteins were selected from (i) a screening with 4595 antibodies and 32 serum samples from melanoma patients and controls, (ii) antibodies used for immunohistochemistry, (iii) protein targets previously related with melanoma. The analysis was performed with 149 serum samples from patients with malignant melanoma. Antibody selectivity was then assessed by Western blot, immunocapture mass spectrometry, and epitope mapping. Lastly, indicative antibodies were applied for IHC analysis of melanoma tissues. RESULTS: Serum levels of regucalcin (RGN) and syntaxin 7 (STX7) were found to be lower in patients with both recurring tumors and a high Breslow's thickness (T-stage 3/4) compared to low thickness (T-stage 1/2) without disease recurrence. Serum levels of methylenetetrahydrofolate dehydrogenase 1-like (MTHFD1L) were instead elevated in sera of T3/4 patients with recurrence. The analysis of tissue sections with S100A6 and MTHFD1L showed positive staining in a majority of patients with melanoma, and S100A6 was significantly associated to T-stage. CONCLUSIONS: Our findings provide a starting point to further study RGN, STX7, MTHFD1L and S100A6 in serum to elucidate their involvement in melanoma progression and to assess a possible contribution to support clinical indications.     

宿主感染马红球菌的免疫机制

马红球菌(Rhodococcus equi)作为一种人兽共患病原菌,主要引起3～6月龄马和免疫缺陷患者肺部相关疾病,病死率为50%～80%;此外还可以感染猪、羊、猫、狗、骆驼等动物。该菌不仅对马业造成严重经济损失,还危害免疫缺陷患者的健康,因此在世界范围内受到公共卫生学的重视。马红球菌感染宿主后,其通过抑制吞噬体/自噬体与溶酶体的融合抵抗巨噬细胞杀伤从而进行免疫逃逸;此外,由于马驹固有免疫和适应性免疫存在功能缺陷使其不能有效抵抗马红球菌感染。目前关于宿主感染马红球菌的免疫机制尚未阐述清楚,从马红球菌与宿主免疫细胞相互作用的角度出发,就宿主感染马红球菌的免疫机制进行综述,以期更好地了解马红球菌感染的免疫机制,同时为该菌所引发疾病的防治策略提供参考。     

猫爪草提取物对结核分枝杆菌临床分离株的可能作用靶标

利用双向电泳技术, 对猫爪草提取物作用前后的结核分枝杆菌临床分离株的全细胞蛋白表达图谱进行差异比较和分析, 发现其中22个蛋白质斑点的浓度具有差异,利用基质辅助激光解吸/电离飞行时间质谱技术, 对其中4个表达明显下调和1个明显上调的蛋白质斑点进行分析鉴定, 获得5个明确的肽质量指纹图谱.通过数据库检索, 确定这5个蛋白质分别为S-腺苷甲硫氨酸合成酶、吲哚-3-甘油磷酸合酶、烯酰-CoA水合酶、琥珀酰辅酶A合成酶和60 kD的分子伴侣2.其中前4个分子是首次报道参与结核分枝杆菌的重要生理活动.该结果有助于了解猫爪草提取物对结核分枝杆菌生理的影响, 为进一步确定中药猫爪草提取物对结核分枝杆菌的作用靶标和机理提供了基础.     

Cryptococcal Interactions with the Host Immune System

Opportunistic pathogens have become of increasing medical importance over the last decade due to the AIDS pandemic. Not only is cryptococcosis the fourth-most-common fatal infectious disease in sub-Saharan Africa, but also Cryptococcus is an emerging pathogen of immunocompetent individuals. The interaction between Cryptococcus and the host''s immune system is a major determinant for the outcome of disease. Despite initial infection in early childhood with Cryptococcus neoformans and frequent exposure to C. neoformans within the environment, immunocompetent individuals are generally able to contain the fungus or maintain the yeast in a latent state. However, immune deficiencies lead to disseminating infections that are uniformly fatal without rapid clinical intervention. This review will discuss the innate and adaptive immune responses to Cryptococcus and cryptococcal strategies to evade the host''s defense mechanisms. It will also address the importance of these strategies in pathogenesis and the potential of immunotherapy in cryptococcosis treatment.The basidiomycetous yeast genus Cryptococcus includes the two medically important pathogens C. neoformans and C. gattii. These two species are further divided into C. neoformans serotypes A (C. neoformans var. grubii), D (C. neoformans var. neoformans), and A/D and C. gattii serotypes B and C (formerly C. neoformans var. gattii) based on differential antibody recognition of the polysaccharide capsule (135). The two pathogenic species show different geographical distributions. C. neoformans is globally distributed and has been isolated from various natural sources, with particularly high concentrations occurring in avian guano, rotting vegetables, and soil. In contrast, C. gattii is geographically restricted to tropical and subtropical regions, with the notable exception of British Columbia. In tropical and subtropical regions, it has been found to be associated with the eucalyptus species Eucalyptus camaldulensis, Eucalyptus tereticornis, Eucalyptus rudis, and Eucalyptus gomphocephala (64, 172). C. neoformans causes mainly opportunistic infections in immunocompromised patients with underlying conditions, such as HIV, leukemia, and other cancers, or in those taking corticosteroid medication (135). Serotype A is responsible for the majority of cryptococcosis cases in immunocompromised hosts (135). In contrast, C. gattii affects mainly immunocompetent individuals. The recent and spreading cryptococcosis outbreak in healthy individuals in British Columbia has highlighted the potential of C. gattii to act as an emerging pathogen (84, 85, 121). In addition, other non-C. neoformans/non-C. gattii species, such as Cryptococcus laurentii and Cryptococcus albidus, have recently started to emerge as potential human pathogens (83).Cryptococcal infection can be asymptomatic, chronic, or acute. Typically, an initial pulmonary infection can spread systemically, with a particular predilection for the central nervous system. Pulmonary infections are in most cases asymptomatic. However, they can involve coughing, pleuritic chest pain, fever, dyspnoea, weight loss, and malaise. Pneumonia and acute respiratory distress syndrome have been reported mainly for immunocompromised patients (17, 141). Cryptococcosis of the central nervous system is life threatening and presents as meningitis or meningoencephalitis, with symptoms such as headache, increased intracranial pressure, fever, lethargy, coma, personality changes, and memory loss. Less common are secondary infections of the skin, lungs, prostate, and eye (135). A recent publication estimated 957,900 cases of cryptococcal meningitis resulting in 624,700 deaths globally each year (150). It is the leading cause of death in HIV-infected individuals, with an incidence of 30% and a mortality of 30 to 60%. The mortality rate in transplant patients is even higher (20 to 100%) (Centers for Disease Control and Prevention) (135).The dramatic course of Cryptococcus infections in immunocompromised individuals shows the importance of an intact immune response to the pathogen. This review will consider both the host''s innate and adaptive immune responses to C. neoformans and C. gattii together with the pathogens'' strategy to undermine these defense mechanisms and how current knowledge might be applied to improve anticryptococcal therapy.     

CFTR Protects against Mycobacterium abscessus Infection by Fine-Tuning Host Oxidative Defenses

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Genome-Wide RNAi Screen Identifies Broadly-Acting Host Factors That Inhibit Arbovirus Infection

Vector-borne viruses are an important class of emerging and re-emerging pathogens; thus, an improved understanding of the cellular factors that modulate infection in their respective vertebrate and insect hosts may aid control efforts. In particular, cell-intrinsic antiviral pathways restrict vector-borne viruses including the type I interferon response in vertebrates and the RNA interference (RNAi) pathway in insects. However, it is likely that additional cell-intrinsic mechanisms exist to limit these viruses. Since insects rely on innate immune mechanisms to inhibit virus infections, we used Drosophila as a model insect to identify cellular factors that restrict West Nile virus (WNV), a flavivirus with a broad and expanding geographical host range. Our genome-wide RNAi screen identified 50 genes that inhibited WNV infection. Further screening revealed that 17 of these genes were antiviral against additional flaviviruses, and seven of these were antiviral against other vector-borne viruses, expanding our knowledge of invertebrate cell-intrinsic immunity. Investigation of two newly identified factors that restrict diverse viruses, dXPO1 and dRUVBL1, in the Tip60 complex, demonstrated they contributed to antiviral defense at the organismal level in adult flies, in mosquito cells, and in mammalian cells. These data suggest the existence of broadly acting and functionally conserved antiviral genes and pathways that restrict virus infections in evolutionarily divergent hosts.     

Infection of Acanthamoeba castellanii with Mycobacterium bovis and M. bovis BCG and Survival of M. bovis within the Amoebae

Survival of Mycobacterium bovis after ingestion by protozoa would provide an environmental reservoir for infection of cattle. We have shown that M. bovis survived ingestion by Acanthamoeba castellanii. In contrast, two strains of M. bovis BCG did not survive well within Acanthamoeba.     

Infection of Acanthamoeba castellanii with Mycobacterium bovis and M. bovis BCG and survival of M. bovis within the amoebae

Survival of Mycobacterium bovis after ingestion by protozoa would provide an environmental reservoir for infection of cattle. We have shown that M. bovis survived ingestion by Acanthamoeba castellanii. In contrast, two strains of M. bovis BCG did not survive well within Acanthamoeba.     

Proteins of Mycobacterium bovis BCG induced in the Wayne dormancy model

Oxygen starvation triggers the shiftdown of the obligate aerobe Mycobacterium bovis BCG to a state of dormancy. Two-dimensional electrophoresis showed a drastic up-regulation of the alpha-crystallin homolog, the putative response regulator Rv3133c, and the two conserved hypothetical proteins Rv2623 and Rv2626c in dormant bacilli.     

结核杆菌感染T细胞介导免疫应答研究的新进展

结核病对免疫学家构成了巨大的挑战,因为它是一种慢性传染性疾病,病原体具有持久性特点.在对人和动物进行实验时,检测到结核分枝杆菌适应性免疫应答的特点之一为感染早期T细胞免疫应答延迟.新近研究揭示了此种延迟应答的机制:通过结核杆菌抑制免疫细胞(CD4+和CD8+T细胞及DC)凋亡延迟应答,通过特异性Treg细胞抑制作用延迟应答.结核杆菌慢性感染期间存在IFNγ信号调节网络和ESAT-6抗原的慢性刺激作用,抗原特异性PD-1+ CD4+T细胞具有高度增殖分化为更多终末效应性T细胞的潜能,以此可调节和维持免疫应答.深入了解抗原特异性T细胞调节与维持适应性免疫应答的机制,有益于抗结核疫苗的设计和研制.     

Enterovirus71 (EV71) Utilise Host microRNAs to Mediate Host Immune System Enhancing Survival during Infection

Hand, Foot and Mouth Disease (HFMD) is a self-limiting viral disease that mainly affects infants and children. In contrast with other HFMD causing enteroviruses, Enterovirus71 (EV71) has commonly been associated with severe clinical manifestation leading to death. Currently, due to a lack in understanding of EV71 pathogenesis, there is no antiviral therapeutics for the treatment of HFMD patients. Therefore the need to better understand the mechanism of EV71 pathogenesis is warranted. We have previously reported a human colorectal adenocarcinoma cell line (HT29) based model to study the pathogenesis of EV71. Using this system, we showed that knockdown of DGCR8, an essential cofactor for microRNAs biogenesis resulted in a reduction of EV71 replication. We also demonstrated that there are miRNAs changes during EV71 pathogenesis and EV71 utilise host miRNAs to attenuate antiviral pathways during infection. Together, data from this study provide critical information on the role of miRNAs during EV71 infection.