RNA-DEPENDENT RNA POLYMERASE ASSOCIATED WITH WHEAT ROSETTE STUNT VIRIONS

Wheat rosette stunt virus (WRSV) contains an RNA-dependent RNA polymerase. The RNA polymerase activity is associated with the viral nucleocapsid (NP).In vitro transcription of purified NP required all of the four nucleoside triphosphates and Mg^(2+).There was a need of a proper salt concentration and some reducing reagents in the system for increasing the RNA polymerase activity.The optimum temperature for in vitro transcription was around 25℃.Within the first 90 min of in vitro reaction, incorporation rose linearly with the time course of incubation. The experiments of ribonuclease and deoxyribonuclease treatments showed that single-stranded RNAs were synthesized in vitro by the RNA polymerase.Two fractions of WRSV-NP could be separated by SDS-dissociation and ultracentrifugation.The supernatant fraction contained three structural proteins of NP: L, N and NS;and the pellet fraction contained the viral RNA.When the supernatant proteins and the viral RNA were mixed together, RNA polymerase activity could be reconstituted.When the ratio between the amounts of the supernatant proteins and the viral RNA in the mixture was about 100:7.7, the reconstituted RNA polymerase activity reached the maximum.

Avian hepatitis B viruses： Molecular and cellular biology, phylogenesis, and host tropism

The human hepatitis B virus （HBV） and the duck hepatitis B virus （DHBV） share several fundamental features. Both viruses have a partially double-stranded DNA genome that is replicated via a RNA intermediate and the coding open reading frames （ORFs） overlap extensively. In addition, the genomic and structural organization, as well as replication and biological characteristics, are very similar in both viruses. Host of the key features of hepadnaviral infection were first discovered in the DHBV model system and subsequently confirmed for HBV. There are, however, several differences between human HBV and DHBV. This review will focus on the molecular and cellular biology, evolution, and host adaptation of the avian hepatitis B viruses with particular emphasis on DHBV as a model system.

Observation of Ultrastructure in Lesions of Condyloma Acuminatum

Objective: To explore the effect of morphological changes in the development of condyloma acuminatum (CA) Materials and Methods: Lesions in five patients with CA were observed . Results: Upon electron microscopy, the most characteristic feature of the lesions important for diagnosis, was the presence of distinct perinuclear vacuolizations, or so-called koilocytes, among some epithelial cells. These cells possessed hyperchromatic nuclei, swollen mitochondria, dilated endoplasmic reticulum and dissolved glycogen. There were interchromatin granules and perichromatin granules in some nuclei. Moreover some virus particles were also seen in the nuclei of some infected cells. Conclusions: The ultrastructural findings may be used to histopathologically explain the pathogenesis and mechanism of this disease, and it is helpful for diagnosis of CA .

Vif基因体外表达载体构建及其在无细胞系统中的表达

随着-omics(组学)时代的到来,无细胞蛋白质合成系统以具有快速、方便、易于高通量等优点,正在被广泛地研究和应用。本文选取HIV病毒感染因子Vif作为目标蛋白,构建了适宜体外表达的Vif表达载体pIVEX2.4c-Vif,并将其在大肠杆菌无细胞蛋白质合成系统中进行表达,为下一步进行高通量药物筛选奠定了一定的基础。

Analysis of hepatitis B virus preS1 variability and prevalence of the rs2296651 polymorphism in a Spanish population

AIM To determine the variability/conservation of the domain of hepatitis B virus(HBV) pre S1 region that interacts with sodium-taurocholate cotransporting polypeptide(hereafter, NTCP-interacting domain) and the prevalence of the rs2296651 polymorphism(S267 F, NTCP variant) in a Spanish population. METHODS Serum samples from 246 individuals were included and divided into 3 groups: patients with chronic HBV infection(CHB)(n = 41, 73% Caucasians), patients with resolved HBV infection(n = 100, 100% Caucasians) and an HBV-uninfected control group(n = 105, 100% Caucasians). Variability/conservation of the amino acid(aa) sequences of the NTCPinteracting domain,(aa 2-48 in viral genotype D) and a highly conserved pre S1 domain associated with virion morphogenesis(aa 92-103 in viral genotype D) were analyzed by next-generation sequencing and compared in 18 CHB patients with viremia > 4 log IU/mL. The rs2296651 polymorphism was determined in all individuals in all 3 groups using an in-house real-time PCR melting curve analysis.RESULTS The HBV pre S1 NTCP-interacting domain showed a high degree of conservation among the examined viral genomes especially between aa 9 and 21(in the genotype D consensus sequence). As compared with the virion morphogenesis domain, the NTCPinteracting domain had a smaller proportion of HBV genotype-unrelated changes comprising > 1% of the quasispecies(25.5% vs 31.8%), but a larger proportion of genotype-associated viral polymorphisms(34% vs 27.3%), according to consensus sequences from Gen Bank patterns of HBV genotypes A to H. Variation/conservation in both domains depended on viral genotype, with genotype C being the most highly conserved and genotype E the most variable(limited finding, only 2 genotype E included). Of note, proline residues were highly conserved in both domains, and serine residues showed changes only to threonine or tyrosine in the virion morphogenesis domain. The rs2296651 polymorphism was not detected in any participant.CONCLUSION In our CHB population, the NTCP-interacting domain was highly conserved, particularly the proline residues and essential amino acids related with the NTCP interaction, and the prevalence of rs2296651 was low/null.

Open reading frame 3 protein of hepatitis E virus:Multi-function protein with endless potential

Hepatitis E virus (HEV), a fecal-orally transmitted foodborne viral pathogen,causes acute hepatitis in humans and is responsible for hepatitis E outbreaksworldwide. Since the identification of HEV as a zoonotic agent, this virus has beenisolated from a variety of hosts with an ever-expanding host range. HEV-openreading frame (ORF) 3, the smallest ORF in HEV genomes, initially had beenperceived as an unremarkable HEV accessory protein. However, as novel HEVORF3function has been discovered that is related to the existence of a putativethird virion structural form, referred to as “quasi-enveloped” HEV particles, HEVis challenging the conventional virion structure-based classification scheme,which assigns all viruses to two groups, “enveloped” or “non-enveloped”. In thisreview, we systematically describe recent progress that has identified multiplepathogenic roles of HEV-ORF3, including roles in HEV virion release, biogenesisof quasi-enveloped virus, regulation of the host innate immune response, andinterference with host signaling pathways. In addition, implications of HEVORF3-associated quasi-enveloped virions are discussed to guide futuredevelopment of improved vaccines against zoonotic HEV infection.

Role of the virion host shutoff protein in neurovirulence of monkey B virus(Macacine herpesvirus 1)

Monkey B virus(Macacine herpesvirus 1; BV) is noted for its extreme neurovirulence in humans. Since the vhs protein encoded by the UL41 gene has been shown to be a neurovirulence factor in the related human herpes simplex viruses, the role of the UL41 gene in BV neurovirulence was investigated. BV mutants were constructed that lacked the entire UL41 ORF(Δ41) or had the RNase active site mutated(Δ41A). Neither mutant shut off host protein synthesis, degraded β-actin mRNA, or prevented an IFN-β response, indicating that the vhs protein and its RNase activity are both necessary for these activities. Replication of both mutants in primary mouse cells was impaired and they exhibited a prolonged disease course in mice. Whereas Δ41 infected mice were euthanized for symptoms related to central nervous system(CNS) infection, Δ41A infected mice were euthanized primarily for symptoms of autonomic nervous system dysfunction. While neuroinvasiveness was not affected, lesions in the CNS were more limited in size, anatomical distribution, and severity than for wild-type virus. These results indicate that the vhs protein affects the general replicative efficiency of BV in vivo rather than being a specific neurovirulence factor critical for invasion of or preferential replication in the CNS.

The Dicistroviridae: An Emerging Family of Invertebrate Viruses

Dicistroviruses comprise a newly characterized and rapidly expanding family of small RNA viruses of invertebrates. Several features of this virus group have attracted considerable research interest in recent years. In this review I provide an overview of the Dicistroviridae and describe progress made toward the understanding and practical application of dicistroviruses, including (i) construction of the first infectious clone of a dicistrovirus, (ii) use of the baculovirus expression system for production of an infectious dicistrovirus, (iii) the use of Drosophila C virus for analysis of host response to virus infection, and (iv) correlation of the presence of Israeli acute paralysis virus with honey bee colony collapse disorder. The potential use of dicistroviruses for insect pest management is also discussed. The structure, mechanism and practical use of the internal ribosome entry site (IRES) elements has recently been reviewed elsewhere.

Cell culture-adaptive mutations in hepatitis C virus promote viral production by enhancing viral replication and release

AIM To explore hepatitis C virus(HCV) adaptive mutations or combinations thereof responsible for enhanced viral production and investigate the underlying mechanisms.METHODS A series of plasmids with adaptive mutations were constructed. After the plasmids were transfected into Huh7.5 cells, we determined the infectious HCV particle titers by NS5 A immunofluorescence assays, and detected HCV RNA replication by real-time PCR and protein expression by Western blot. Then we carried out immunoblotting of supernatants and celllysates with anti-NS3 to analyze the virus release level. In addition, co-localization of lipid droplets(LDs) with NS5 A was measured using confocal laser scanning microscopy. The ratio between the p56 and p58 phosphoforms of NS5 A was analyzed further.RESULTS The plasmids named JFH1-m E2, JFH1-mp7, JFH1-m NS4 B, JFH1-m NS5 A, JFH1-m E2/NS5 A, JFH1-mp7/NS5 A, JFH1-m NS4 B/NS5 A, JFH1-m E2/p7/NS5 A, and m JFH1 were constructed successfully. This study generated infectious HCV particles with a robust titer of 1.61 × 106 focus-forming units(FFUs)/m L. All of the six adaptive mutations increased the HCV particle production at varying levels. The NS5 A(C2274 R, I2340 T, and V2440 L) and p7(H781 Y) were critical adaptive mutations. The effect of NS5 A(C2274 R, I2340 T, and V2440 L), p7(H781 Y), and NS4 B(N1931 S) on infectious HCV titers was investigated by measuring the HCV RNA replication, protein expression, and virion release. However, the six adaptive mutations were not required for the LD localization of NS5 A proteins or the phosphorylation of NS5 A.CONCLUSION In this study, we generated infectious HCV particles with a robust titer of 1.61 × 106 FFUs/m L, and found that the viral replication and release levels could be enhanced by some of the adaptive mutations.

Virion Proteomics of Large DNA Viruses

Large DNA viruses normally have complex structures with many of protein components derived from both viral and host origins. The development in proteomics, especially mass spectrometry identification techniques provide powerful tools for analyzing large viruses. In this review, we have summarized the recent achievements on proteomic studies of large DNA viruses, such as herpesvirus, poxvirus, nimavirus and baculoviruse. The proteomics of baculovirus occlusion-derived virions (ODV) were emphasized. Different mass spectrometry techniques used on various baculoviruses were introduced, and the identified structurally associated proteins of baculoviruses are summarized.

Possibility of Evolution in Culture of the <i>Oryctes</i>Nudivirus of the Coconut Rhinoceros Beetle <i>Oryctes rhinoceros</i>(Coleoptera: Scarabaeidae: Dynastinae)

It is suggested that the isolates of Oryctes Nudivirus (OrNV), cultured for decades in cells of Heteronychus arator (F.) (HA), be checked to verify genomic changes have not occurred which adapt them to culture but reduce or cancel their ability to infect the target pest, the coconut rhinoceros beetle (CRB), Oryctes rhinoceros (L.). Full genomes of field-caught OrNV isolates, and their infectivity against larvae and adults, could be compared with those of HA-cultured isolates. Further data to correlate OrNV dosage indices with doses in number of virions/ml could be advantageous so as to explore if CRB larvae or adults may resist infection by a sub-threshold dose. Also the possibility of changes in the HA culture cells which alter the outer coat of the resulting virion, hence perhaps its infectivity towards CRB cells, could be checked. Might it be possible to move beyond HA-culture and develop tissue culture of Oryctes rhinoceros cells for mass production of OrNV as this beetle species is the target? Nuclear genomes of OrNV-resistant and OrNV-susceptible strains of the CRB could be examined for changes perhaps correlated with resistance. The possibility of endosymbiotic bacteria affecting CRB susceptibility to OrNV might be checked.

Purification of <i>Dengue Virus</i>Particles by One-Step Ceramic Hydroxyapatite Chromatography

Dengue virus type 2 ThNH7/93 retained infectious activity after purification by ceramic hydroxyapatite chromatogra-phy. Dengue virus type 2 culture fluid was loaded onto the ceramic hydroxyapatite column and eluted with a linear gradient of sodium phosphate buffer. Culture fluid and protein contaminants derived from host cells were eluted initially, followed by elutions of dsDNA, and then dengue virus type 2. The recoveries of dengue virus type 2 were 64 ± 14% (n = 11) in the hemagglutination (HA) test and 60% (n = 2) determined by focus assay for viral infectivity. This protocol was highly reproducible, simple, rapid, and appears applicable to other virus species such as influenza virus, Japanese encephalitis virus and adenovirus.

Geometric architecture of viruses

In the current SARS-CoV-2 disease(COVID-19)pandemic,the structural understanding of new emerging viruses in relation to developing effective treatment and interventions are very necessary.Viruses present remarkable differences in geometric shapes,sizes,molecular compositions and organizations.A detailed structural knowledge of a virion is essential for understanding the mechanisms of capsid assembly/disassembly,antigenicity,cell-receptor interaction,and designing therapeutic strategies.X-ray crystallography,cryoelectron microscopy and molecular simulations have elucidated atomic-level structure of several viruses.In view of this,a recently determined crystal structure of SARS-CoV-2 nucleocapsid has revealed its architecture and self-assembly very similar to that of the SARS-CoV-1 and the Middle-East respiratory syndrome virus(MERS-CoV).In structure determination,capsid symmetry is an important factor greatly contributing to its stability and balance between the packaged genome and envelope.Since the capsid protein subunits are asymmetrical,the maximum number of inter-subunit interactions can be established only when they are arranged symmetrically.Therefore,a stable capsid must be in a perfect symmetry and lowest possible free-energy.Isometric virions are spherical but geometrically icosahedrons as compared to complex virions that are both isometric and helical.Enveloped icosahedral or helical viruses are very common in animals but rare in plants and bacteria.Icosahedral capsids are defined by triangulation number(T=1,3,4,13,etc.),i.e.,the identical equilateral-triangles formed of subunits.Biologically significant defective capsids with or without nucleic acids are common in enveloped alpha-,flavi-and hepadnaviruses.The self-assembling,stable and non-infectious virus-like particles have been widely exploited as vaccine candidates and therapeutic molecules delivery vehicles.

Genetic analysis of structural proteins in the adsorption apparatus of bacteriophage epsilon 15

AIM: To probe the organizational structure of the adsorption apparatus of bacteriophage epsilon 15(E15) using genetic and biochemical methodology METHODS: Hydroxylamine was used to create nonsense mutants of bacteriophage E15. The mutants were then screened for defects in their adsorption apparatus proteins, initially by measuring the concentrations of free tail spike proteins in lysates of cells that had been infected by the phage mutants under nonpermissive growth conditions. Phage strains whose infected cell lysates contained above-average levels of free tail spike protein under non-permissive growth conditions were assumed to contain nonsense mutations in genes coding for adsorption apparatus proteins.These mutants were characterized by classical genetic mapping methods as well as automated sequencing of several of their genes. Finally, sodium dodecyl sulfatepolyacrylamide gel electrophoresis and autoradiography were used to examine the protein compositions of the radioactive particles produced when the various mutants were grown on a non-permissive host cell in the presence of 35S-methionine and co-purified along with E15 wt phage on Cs Cl block gradients.RESULTS: Our results are consistent with gp4 forming the portal ring structure of E15. In addition, they show that proteins gp15 and gp17 likely comprise the central tube portion of the E15 adsorption apparatus, with gp17 being more distally positioned than gp15 and dependent upon both gp15 and gp16 for its attachment. Finally, our data indicates that tail spike proteins comprised of gp20 can assemble onto nascent virions that contain gp7, gp10, gp4 and packaged DNA, but which lack both gp15 and gp17, thereby forming particles that are of sufficient stability to survive Cs Cl buoyant density centrifugation.CONCLUSION: The portal ring(gp4) of E15 is bound to tail spikes(gp20) and the tail tube(gp15 and gp17); gp17's attachment requires both gp15 and gp16.

季节性流感裂解疫苗安尔来福（R）的安全性、免疫原性及与H7N9禽流感病毒的交叉免疫研究

目的 评价季节性流感裂解疫苗（安尔来福（R））的免疫原性及安全性,分析与H7N9禽流感病毒的交叉免疫反应.方法 采用临床研究开放式设计,选择6 ～ 35月龄婴幼儿（免疫接种方式：2针,0、28 d）、18～ 60岁成年人及＞60岁老年人（1针）接种安尔来福（R）.所有接种者免疫后均接受安全性观察,并采集成年人和老年人免疫前后21d的血清标本,利用血凝抑制试验（HI）检测疫苗3种（甲型流感2种和乙型流感1种）病毒株以及H7N9禽流感病毒抗体.采用欧盟流感疫苗临床研究标准（欧盟标准）评价疫苗免疫效果.结果 共202（婴幼儿65、成年人69及老年人68）人完成接种和安全性观察.不良反应发生率为12.4％（25/202）,以全身不良反应为主,未见严重不良反应.有124（成年人64、老年人60）人采集到免疫前后配对血清.接种疫苗后21d,成年组3个型别HI抗体阳转率为78.1％ ～ 90.6％,抗体保护率为92.2％ ～ 100.0％,GMT增长7.9～41.0倍;老年组HI抗体阳转率为66.7％ ～ 83.3％,抗体保护率为86.7％ ～ 100.0％,GMT增长5.7 ～ 20.4倍.均达到欧盟标准.而接种疫苗后,成年组和老年组抗H7N9抗体阳性率和阳转率仍保持为零,GMT增长仅1.2～1.4倍.结论 季节性灭活流感裂解疫苗的安全性和免疫原性良好,但对H7N9禽流感病毒无交叉免疫反应.

Viral proteomics: The emerging cutting-edge of virus research

Viruses replicate and proliferate in host cells while continuously adjusting to and modulating the host environment.They encode a wide spectrum of multifunctional proteins,which interplay with and modify proteins in host cells.Viral genomes were chronologically the first to be sequenced.However,the corresponding viral proteomes,the alterations of host proteomes upon viral infection,and the dynamic nature of proteins,such as post-translational modifications,enzymatic cleavage,and activation or destruction by proteolysis,remain largely unknown.Emerging high-throughput techniques,in particular quantitative or semi-quantitative mass spectrometry-based proteomics analysis of viral and cellular proteomes,have been applied to define viruses and their interactions with their hosts.Here,we review the major areas of viral proteomics,including virion proteomics,structural proteomics,viral protein interactomics,and changes to the host cell proteome upon viral infection.

Cryo-EM Studies of Virus-Antibody Immune Complexes

Antibodies play critical roles in neutralizing viral infections and are increasingly used as therapeutic drugs and diagnostic tools. Structural studies on virus-antibody immune complexes are important for better understanding the molecular mechanisms of antibody-mediated neutralization and also provide valuable information for structure-based vaccine design.Cryo-electron microscopy(cryo-EM) has recently matured as a powerful structural technique for studying bio-macromolecular complexes. When combined with X-ray crystallography, cryo-EM provides a routine approach for structurally characterizing the immune complexes formed between icosahedral viruses and their antibodies. In this review, recent advances in the structural understanding of virus-antibody interactions are outlined for whole virions with icosahedral T = pseudo 3(picornaviruses) and T = 3(flaviviruses) architectures, focusing on the dynamic nature of viral shells in different functional states. Glycoprotein complexes from pleomorphic enveloped viruses are also discussed as immune complex antigens. Improving our understanding of viral epitope structures using virus-based platforms would provide a fundamental road map for future vaccine development.

Proteomic Profiling of Purified Rabies Virus Particles

While host proteins incorporated into virions during viral budding from infected cell are known to play essential roles in multiple process of the life cycle of progeny virus,these characteristics have been largely neglected in studies on rabies virus(RABV).Here,we purified the RABV virions with good purity and integrity,and analyzed their proteome by nano LC–MS/MS,followed by the confirmation with immunoblot and immuno-electronic microscopy.In addition to the 5 viral proteins,49 cellular proteins were reproducibly identified to be incorporated into matured RABV virions.Function annotation suggested that 24 of them were likely involved in virus replication.Furthermore,cryo-EM was employed to observe the purified RABV virions,generating high-resolution pictures of the bullet-shaped virion structure of RABV.This study has provided new insights into the host proteins composition in RABV virion and shed the light for further investigation on molecular mechanisms of RABV infection,as well as the discovery of new anti-RABV therapeutics.