非结构蛋白在非洲猪瘟病毒感染中作用

非洲猪瘟(African swine fever,ASF)是由非洲猪瘟病毒(African swine fever virus,ASFV)感染引起的一种急性、出血性猪传染病,给疫情发生国家(地区)的养猪业造成重大经济损失.ASFV为双股DNA病毒,基因组含有150～167个开放阅读框(ORFs),可编码150～200种蛋白质,其中非结构蛋白有100余种.ASFV编码的酶、转录因子、调节宿主细胞功能蛋白和病毒免疫逃逸相关蛋白等作为重要的非结构蛋白,在病毒核苷酸代谢、DNA复制、修复、转录、蛋白修饰以及病毒与宿主细胞相互作用等过程中发挥重要作用,但仍有许多非结构蛋白的功能尚不明晰.因此,本文综述了 ASFV非结构蛋白在病毒感染中的作用,以期为ASFV非结构蛋白的进一步研究提供参考.     

Antiviral Role of IFITM Proteins in African Swine Fever Virus Infection

The interferon-induced transmembrane (IFITM) protein family is a group of antiviral restriction factors that impair flexibility and inhibit membrane fusion at the plasma or the endosomal membrane, restricting viral progression at entry. While IFITMs are widely known to inhibit several single-stranded RNA viruses, there are limited reports available regarding their effect in double-stranded DNA viruses. In this work, we have analyzed a possible antiviral function of IFITMs against a double stranded DNA virus, the African swine fever virus (ASFV). Infection with cell-adapted ASFV isolate Ba71V is IFN sensitive and it induces IFITMs expression. Interestingly, high levels of IFITMs caused a collapse of the endosomal pathway to the perinuclear area. Given that ASFV entry is strongly dependent on endocytosis, we investigated whether IFITM expression could impair viral infection. Expression of IFITM1, 2 and 3 reduced virus infectivity in Vero cells, with IFITM2 and IFITM3 having an impact on viral entry/uncoating. The role of IFITM2 in the inhibition of ASFV in Vero cells could be related to impaired endocytosis-mediated viral entry and alterations in the cholesterol efflux, suggesting that IFITM2 is acting at the late endosome, preventing the decapsidation stage of ASFV.     

人免疫缺陷病毒1型Rev单链抗体细胞内免疫抗病毒基因治疗研究

应用抗ＨＩＶ－１Ｒｅｖ单链抗体细胞内免疫方法,研究在人Ｔ细胞和周围血淋巴单核细胞内抗病毒复制的效果,探讨细胞内免疫抗ＨＩＶ－１基因治疗的可行性。克隆抗ＨＩＶ－１Ｒｅｖ单链抗抗体（ｓＦｖ）基因,以逆转录病毒为基因载体,将名装后的含靶基因的逆转录病毒转导至人ＣＤ４阳性Ｔ－细胞株ＣＥＭ和ＳｕｐＴ１,以及ＨＩＶ－１阴性自愿者的周围血淋巴单核细胞（ＰＢＭＣ）,再分别用不同剂量（ＭＯＩ）的ＨＩＶ－１病毒株ＰＮ     

The Coronavirus Transmissible Gastroenteritis Virus Causes Infection after Receptor-Mediated Endocytosis and Acid-Dependent Fusion with an Intracellular Compartment

Aminopeptidase N is a species-specific receptor for transmissible gastroenteritis virus (TGEV), which infects piglets, and for the 229E virus, which infects humans. It is not known whether these coronaviruses are endocytosed before fusion with a membrane of the target cell, causing a productive infection, or whether they fuse directly with the plasma membrane. We have studied the interaction between TGEV and a cell line (MDCK) stably expressing recombinant pig aminopeptidase N (pAPN). By electron microscopy and flow cytometry, TGEV was found to be associated with the plasma membrane after adsorption to the pAPN-MDCK cells. TGEV was also observed in endocytic pits and apical vesicles after 3 to 10 min of incubation at 38°C. The number of pits and apical vesicles was increased by the TGEV incubation, indicating an increase in endocytosis. After 10 min of incubation, a distinct TGEV-pAPN-containing population of large intracellular vesicles, morphologically compatible with endosomes, was found. A higher density of pAPN receptors was observed in the pits beneath the virus particles than in the surrounding plasma membrane, indicating that TGEV recruits pAPN receptors before endocytosis. Ammonium chloride and bafilomycin A₁ markedly inhibited the TGEV infection as judged from virus production and protein biosynthesis analyses but did so only when added early in the course of the infection, i.e., about 1 h after the start of endocytosis. Together our results point to an acid intracellular compartment as the site of fusion for TGEV.     

抗胞内菌感染免疫及其治疗

胞内菌感染因其胞内寄生的特点 ,而使得天然免疫、抗体免疫应答和体液抗菌物质等难以对其起作用 ,抗胞内菌感染以细胞免疫为主。CD4+ Th1细胞通过分泌IFN γ激活巨噬细胞 ,杀伤被吞噬的胞内菌 ,亦可通过Th1表达的CD40L与巨噬细胞表面CD40结合而激活巨噬细胞 ;Tc细胞主要经胞毒作用溶解感染的靶细胞 ,裂解所释出的病菌经抗体或补体调理后 ,由吞噬细胞清除。细胞毒T淋巴细胞 (CTL)通过分泌Th1细胞毒细胞因子 ,激活被感染的宿主细胞去杀伤病原体 ,或通过颗粒胞吐途径和Fas/FasL途径介导细胞毒性 ,直接溶解靶细胞和杀伤病原体 ,从而在宿主抗细胞内感染的免疫中充当重要角色。氟喹诺酮类药物因其在胞内的弥散和蓄积作用以及纳米粒药物因其对MPS的被动靶向性 ,成为目前抗胞内菌感染治疗的主要方式 ,而细胞疫苗的研制开发是抗胞内菌感染的最终手段。     

中医药治疗疱疹病毒引发的炎性皮肤病

疱疹病毒引起的炎性皮肤病 ,如带状疱疹常在发疹前或出疹时 ,出现患者难以忍受的痛疼 ,常呈阵发性加剧 ,且在皮损消退后仍可持续数月。生殖器疱疹久治不愈给患者带来难言之隐。我们在进行民间药用资源调查时 ,发现民间利用鲜草药治疗疱疹性疾病具有特色。我院自 1998年 5月～ 2     

Infection of Zebrafish Embryos with Intracellular Bacterial Pathogens

Zebrafish (Danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen interactions ¹. The major cell types of the innate immune system, macrophages and neutrophils, develop during the first days of embryogenesis prior to the maturation of lymphocytes that are required for adaptive immune responses. The ease of obtaining large numbers of embryos, their accessibility due to external development, the optical transparency of embryonic and larval stages, a wide range of genetic tools, extensive mutant resources and collections of transgenic reporter lines, all add to the versatility of the zebrafish model. Salmonella enterica serovar Typhimurium (S. typhimurium) and Mycobacterium marinum can reside intracellularly in macrophages and are frequently used to study host-pathogen interactions in zebrafish embryos. The infection processes of these two bacterial pathogens are interesting to compare because S. typhimurium infection is acute and lethal within one day, whereas M. marinum infection is chronic and can be imaged up to the larval stage ^{2, 3}. The site of micro-injection of bacteria into the embryo (Figure 1) determines whether the infection will rapidly become systemic or will initially remain localized. A rapid systemic infection can be established by micro-injecting bacteria directly into the blood circulation via the caudal vein at the posterior blood island or via the Duct of Cuvier, a wide circulation channel on the yolk sac connecting the heart to the trunk vasculature. At 1 dpf, when embryos at this stage have phagocytically active macrophages but neutrophils have not yet matured, injecting into the blood island is preferred. For injections at 2-3 dpf, when embryos also have developed functional (myeloperoxidase-producing) neutrophils, the Duct of Cuvier is preferred as the injection site. To study directed migration of myeloid cells towards local infections, bacteria can be injected into the tail muscle, otic vesicle, or hindbrain ventricle ^4-6. In addition, the notochord, a structure that appears to be normally inaccessible to myeloid cells, is highly susceptible to local infection ⁷. A useful alternative for high-throughput applications is the injection of bacteria into the yolk of embryos within the first hours after fertilization ⁸. Combining fluorescent bacteria and transgenic zebrafish lines with fluorescent macrophages or neutrophils creates ideal circumstances for multi-color imaging of host-pathogen interactions. This video article will describe detailed protocols for intravenous and local infection of zebrafish embryos with S. typhimurium or M. marinum bacteria and for subsequent fluorescence imaging of the interaction with cells of the innate immune system.     

RNA-Induced Interference with Animal Virus Infection

Some RNAs, including both single- and double-stranded RNAs, when incubated with chick embryo cell culture induce cellular resistance against viruses. Evidence was now obtained indicating that the induction of cellular resistance by RNA depends on the cellular metabolic activity, especially on the synthesis of cellular RNA and protein. Thus, inhibitors of RNA and protein synthesis, actinomycin D and cycloheximide, were found to inhibit the development of an antiviral state when added before, or during the relatively early period of, incubation of the cells with RNA. In the course of induction of cellular resistance, three stages may be distinguished, the priming stage, the developing stage, and the established resistant stage.     

Early Virological and Immunological Events in Asymptomatic Epstein-Barr Virus Infection in African Children

Epstein-Barr virus (EBV) infection often occurs in early childhood and is asymptomatic. However, if delayed until adolescence, primary infection may manifest as acute infectious mononucleosis (AIM), a febrile illness characterised by global CD8+ T-cell lymphocytosis, much of it reflecting a huge expansion of activated EBV-specific CD8+ T-cells. While the events of AIM have been intensely studied, little is known about how these relate to asymptomatic primary infection. Here Gambian children (14–18 months old, an age at which many acquire the virus) were followed for the ensuing six months, monitoring circulating EBV loads, antibody status against virus capsid antigen (VCA) and both total and virus-specific CD8+ T-cell numbers. Many children were IgG anti-VCA-positive and, though no longer IgM-positive, still retained high virus loads comparable to AIM patients and had detectable EBV-specific T-cells, some still expressing activation markers. Virus loads and the frequency/activation status of specific T-cells decreased over time, consistent with resolution of a relatively recent primary infection. Six children with similarly high EBV loads were IgM anti-VCA-positive, indicating very recent infection. In three of these donors with HLA types allowing MHC-tetramer analysis, highly activated EBV-specific T-cells were detectable in the blood with one individual epitope response reaching 15% of all CD8+ T-cells. That response was culled and the cells lost activation markers over time, just as seen in AIM. However, unlike AIM, these events occurred without marked expansion of total CD8+ numbers. Thus asymptomatic EBV infection in children elicits a virus-specific CD8+ T-cell response that can control the infection without over-expansion; conversely, in AIM it appears the CD8 over-expansion, rather than virus load per se, is the cause of disease symptoms.     

Oral Administration of Lactococcus lactis Subsp. lactis JCM5805 Enhances Lung Immune Response Resulting in Protection from Murine Parainfluenza Virus Infection

When activated by viral infection, plasmacytoid dendritic cells (pDCs) play a primary role in the immune response through secretion of IFN-α. Lactococcus lactis subsp. lactis JCM5805 (JCM5805) is a strain of lactic acid bacteria (LAB) that activates murine and human pDCs to express type I and type III interferons (IFNs). JCM5805 has also been shown to activate pDCs via a Toll-like receptor 9 (TLR9) dependent pathway. In this study, we investigated the anti-viral effects of oral administration of JCM5805 using a mouse model of murine parainfluenza virus (mPIV1) infection. JCM5805-fed mice showed a drastic improvement in survival rate, prevention of weight loss, and reduction in lung histopathology scores compared to control mice. We further examined the mechanism of anti-viral effects elicited by JCM5805 administration using naive mice. Microscopic observations showed that JCM5805 was incorporated into CD11c⁺ immune cells in Peyer’s patches (PP) and PP pDCs were significantly activated and the expression levels of IFNs were significantly increased. Interestingly, nevertheless resident pDCs at lung were not activated and expressions levels of IFNs at whole lung tissue were not influenced, the expressions of anti-viral factors induced by IFNs, such as Isg15, Oasl2, and Viperin, at lung were up-regulated in JCM5805-fed mice compared to control mice. Therefore expressed IFNs from intestine might be delivered to lung and IFN stimulated genes might be induced. Furthermore, elevated expressions of type I IFNs from lung lymphocytes were observed in response to mPIV1 ex vivo stimulation in JCM5805-fed mice compared to control. This might be due to increased ratio of pDCs located in lung were significantly increased in JCM5805 group. Taken together, a specific LAB strain might be able to affect anti-viral immunological profile in lung via activation of intestinal pDC leading to enhanced anti-viral phenotype in vivo.     

Intracellular Dynamics of HIV Infection

Early studies of HIV infection dynamics suggested that virus-producing HIV-infected cells had an average half-life of approximately 1 day. However, whether this average behavior is reflective of the dynamics of individual infected cells is unclear. Here, we use HIV-enhanced green fluorescent protein (EGFP) constructs and flow cytometry sorting to explore the dynamics of cell infection, viral protein production, and cell death in vitro. By following the numbers of productively infected cells expressing EGFP over time, we show that infected cell death slows down over time. Although infected cell death in vivo could be very different, our results suggest that the constant decay of cell numbers observed in vivo during antiretroviral treatment could reflect a balance of cell death and delayed viral protein production. We observe no correlation between viral protein production and death rate of productively infected cells, showing that viral protein production is not likely to be the sole determinant of the death of HIV-infected cells. Finally, we show that all observed features can be reproduced by a simple model in which infected cells have broad distributions of productive life spans, times to start viral protein production, and viral protein production rates. This broad spectrum of the level and timing of viral protein production provides new insights into the behavior and characteristics of HIV-infected cells.     

Microwave Enhanced Staining for Plant Virus Inclusions

Plant virus inclusion bodies can be stained specifically with established staining methods for light microscopy. The procedure can be augmented by a short microwave treatment to provide better staining intensity and reduced staining time. The method is useful for preliminary sampling prior to collection for electron microscopy and for plant pathologists, plant breeders, and diagnosticians as a rapid means of plant virus characterization.     

Association of Ribosomes with Intracellular Vesicular Stomatitis Virus Particles

Ribosomes are observed intimately associated with nucleocapsids of vesicular, stomatitis virus, especially those that line structures that are either cytoplasmic vesicles or invaginations of the plasma membrane.     

African Swine Fever Virus Infection Induces Tumor Necrosis Factor Alpha Production: Implications in Pathogenesis

We have analyzed the production of tumor necrosis factor alpha (TNF-α) induced by in vitro infection with African swine fever (ASF) virus (ASFV) and the systemic and local release of this inflammatory cytokine upon in vivo infection. An early increase in TNF-α mRNA expression was detected in ASFV-infected alveolar macrophages, and high levels of TNF-α protein were detected by ELISA in culture supernatants from these cells. When animals were experimentally infected with a virulent isolate (E-75), enhanced TNF-α expression in mainly affected organs correlated with viral protein expression. Finally, elevated levels of TNF-α were detected in serum, corresponding to the onset of clinical signs. TNF-α has been reported to be critically involved in the pathogenesis of major clinical events in ASF, such as intravascular coagulation, tissue injury, apoptosis, and shock. In the present study, TNF-α containing supernatants from ASFV-infected cultures induced apoptosis in uninfected lymphocytes; this effect was partially abrogated by preincubation with an anti-TNF-α specific antibody. These results suggest a relevant role for TNF-α in the pathogenesis of ASF.     

Infection of Cattle with Parainfluenza 3 Virus with Special Reference to Udder Infection

Thirty-seven strains of parainfluenza 3 virus were isolated on bovine kidney cell cultures from Japanese cattle in herds suffering from acute respiratory illness. This finding, together with the clinical and epidemiologic observations and the results of a serologic survey, indicates that in Japan, as in the United States and other countries, this virus is one of the important causes of acute respiratory disease in cattle. A significant finding in the present study is that virus was recovered from milk as well as from nasal secretions. This finding suggests an important role for milk, along with nasal discharges, in disseminating the virus among cattle. In addition, the recovery of virus from milk presents a new problem concerning this infection in cattle, in particular, the potential role of this virus in the pathogenesis of mastitis.     

Latent Herpes Simplex Virus from Trigeminal Ganglia of Rabbits with Recurrent Eye Infection

LATENTLY infected sensory ganglia have been thought to be the source of virus for various clinical manifestations of recurrent herpetic disease in man^1,2. In direct support of this concept, we recently showed that herpes simplex virus can induce a latent infection in the spinal ganglia of mice³. This murine infection has not, however, been shown to be accompanied by recurrent disease. Recurrent herpetic eye infection can be produced in the rabbit⁴. If sensory ganglia are involved in recurrent disease, then trigeminal ganglia from rabbits undergoing such recurrent infection would be expected to harbour latent virus. We now report that herpes simplex virus does indeed induce latent infection in trigeminal ganglia of rabbits presenting recurrent eye infection. As in the experiments with mice, infectious virus could not be recovered directly; it was only found when ganglia were established as organ cultures in vitro.