Bovine virus diarrhea virus in free-living deer from Denmark

Free-living deer are suggested as a possible source of infection of cattle with bovine virus diarrhea (BVD) virus. To examine this hypothesis blood samples from 476 free-living deer were collected during two different periods and tested for BVD virus and antibody in Denmark. In 1995-96, 207 animals were tested. These included 149 roe deer (Capreolus capreolus), 29 fallow deer (Dama dama), 20 red deer (Cervus elaphus) and one sika deer (Cervus sika). For the remaining eight animals no species information was available. In 1998-99, 269 animals were tested including 212 roe deer and 57 red deer. The animals were selected from areas with a relatively high prevalence of cattle herds with a BVD persistent infection status in 1997 and 1998. All 207 samples from 1995-96 were found antibody-negative except two samples from red deer. Only 158 of the 207 samples were tested for virus and were all found negative. Of the 269 samples from 1998-99 all but one were antibody negative. The positive sample was from a red deer. All samples were virus-negative. It appears that BVD infection does not occur in roe deer in Denmark. The presence of antibody in a few red deer from various districts in Jutland probably results from cattle to deer transmission, rather than spread among deer. Hence, the possibility of free-living deer as a source of infection for cattle in Denmark seems to be remote.     

埃博拉病毒/埃博拉病—2014

2014年2月,死亡率极高的埃博拉病(EVD)开始在西部非洲的几内亚暴发流行,接下来,暴发流行出现在塞拉利昂、利比里亚、尼日利亚和塞内加尔另四个西部非洲的国家。现在,几内亚、利比里亚和塞拉利昂的疫情最重。迄今为止,已有4 784人患EVD,且人数仍在倍增,这次暴发流行已成为自40年前EVD被发现以来规模最大的一次,已形成了波及其他地区和国家的巨大危险。在此,综述2014年EVD暴发流行的起因,埃博拉病毒(EBOV)及其传播,EVD的诊断治疗,EBOV疫苗的研制以及EBOV感染的防控。     

Homologous recombination in GB virus C/hepatitis G virus

Analysis of 33 GB virus C/hepatitis G virus (GBV-C/HGV) full or nearly full genome sequences revealed several putative inter- and intrasubtype recombinants. The breakpoints of the recombinant regions were mapped using a maximum-likelihood method, and the statistical significance for each region was tested using Monte Carlo simulation. The results were highly significant and provided evidence for the existence of complex mosaic genomes showing as many as nine recombination events, with breakpoints in the 5' UTR and in all of the coding regions except the short NS4b gene. Recombination was confirmed by separate phylogenetic analysis of the various recombinant regions and by Sawyer's runs test. Taken together, these findings demonstrate for the first time that recombination is common in natural populations of GBV-C and that it takes place both within and between subtypes. The wide-ranging implications of such nonclonal history for reconstructing the spread and timescale of GBV-C evolution are discussed.     

A single amino acid change in rabies virus glycoprotein increases virus spread and enhances virus pathogenicity

Several rabies virus (RV) vaccine strains containing an aspartic acid (Asp) or glutamic acid (Glu) instead of an arginine (Arg) at position 333 of the RV glycoprotein (G) are apathogenic for immunocompetent mice even after intracranial inoculation. However, we previously showed that the nonpathogenic phenotype of the highly attenuated RV strain SPBNGA, which contains a Glu at position 333 of G, is unstable when this virus is passaged in newborn mice. While the Glu(333) remained unchanged after five mouse passages, an Asn(194)-->Lys(194) mutation occurred in RV G. This mutation was associated with increased pathogenicity for adult mice. Using site-directed mutagenesis to exchange Asn(194) with Lys(194) in the G protein of SPBNGA, resulting in SPBNGA-K, we show here that this mutation is solely responsible for the increase in pathogenicity and that the Asn(194)-->Lys(194) mutation does not arise when Asn(194) is exchanged with Ser(194) (SPBNGA-S). Our data presented indicate that the increased pathogenicity of SPBNGA-K is due to increased viral spread in vivo and in vitro, faster internalization of the pathogenic virus into cells, and a shift in the pH threshold for membrane fusion. These results are consistent with the notion that the RV G protein is a major contributor to RV pathogenesis and that the more pathogenic RVs escape the host responses by a faster spread than that of less pathogenic RVs.     

Ectromelia virus RING finger protein is localized in virus factories and is required for virus replication in macrophages.

We have previously described a gene of ectromelia virus (EV) that codes for a 28-kDa RING zinc finger-containing protein (p28) that is nonessential for virus growth in cell culture but is critical for EV pathogenicity in mice (T. G. Senkevich, E. V. Koonin, and R. M. L. Buller, Virology 198:118-128; 1994). Here, we show that, unlike all tested cell cultures, the expression of p28 is required for in vitro replication of EV in murine resident peritoneal macrophages. In macrophages infected with the p28- mutant, viral DNA replication was not detected, whereas the synthesis of at least two early proteins was observed. Immunofluorescence and biochemical analyses showed that in EV-infected macrophages or BSC-1 cells, p28 is associated with virus factories. By use of a vaccinia virus expression system to examine different truncated versions of p28, it was shown that the disruption of the specific structure of the RING domain had no influence on the intracellular localization of this protein. When viral DNA replication was inhibited with cytosine arabinoside, p28 was found in distinct, focal structures that may be precursors to the factories. We hypothesize that in macrophages, which are highly specialized, nondividing cells, p28 substitutes for an unknown cellular factor(s) that may be required for viral DNA replication or a stage of virus reproduction between the expression of early genes and the onset of DNA synthesis. In the absence of p28, the attenuation of EV pathogenicity can be explained by a failure of the virus to replicate in macrophage lineage cells at all successive steps in the spread of virus from the skin to its target organ, the liver.     

Inflammation in virus infections

This review addresses general aspects of the nature of the cellular response in sites of viral pathology. The virus-induced inflammatory process reflects the operation of a broad spectrum of host defence mechanisms ranging, in the phylogenetic sense, from the most primitive (e.g. simple phagocytosis) to the specific immunity characteristic of the higher vertebrates. The pattern of cellular extravasation is also determined by the nature of the particular pathogen, being influenced by such factors as the extent of viral cytopathology and the spectrum of cytokine production. The presence of substantial numbers of activated T cells and macrophages in a particular tissue may have both beneficial and deleterious consequences. We now have a relatively clear concept of the factors governing the specificity of the CD4⁺ and CD8⁺ T lymphocytes that are a central component of the cellular immune response to viruses. Much remains to be learned about the biological events that influence and characterize the effector phase of these T cells in the in vivo situation, and the interactions between various host cell populations in the target organ.     

Rabies virus antinucleoprotein antibody protects against rabies virus challenge in vivo and inhibits rabies virus replication in vitro.

We previously reported that A/WySnJ mice vaccinated via a tail scratch with a recombinant raccoon poxvirus (RCN) expressing the rabies virus internal structural nucleoprotein (N) (RCN-N) were protected against a street rabies virus (D. L. Lodmell, J. W. Sumner, J.J. Esposito, W.J. Bellini, and L. C. Ewalt, J. Virol. 65:3400-3405, 1991). To improve our understanding of the mechanism(s) of this protection, we investigated whether sera of A/WySnJ mice that had been vaccinated with RCN-N but not challenged with street rabies virus had anti-rabies virus activity. In vivo studies illustrated that mice inoculated in the footpad with preincubated mixtures of anti-N sera and virus were protected. In addition, anti-N sera inoculated into the site of virus challenge protected mice. The antiviral activity of anti-N sera was also demonstrated in vitro. Infectious virus was not detected in cultures 24 h following infection with virus that had been preincubated with anti-N sera. At later time points, infectious virus was detected, but inhibition of viral production was consistently > or = 99% compared with control cultures. The protective and antiviral inhibitory activity of the anti-N sera was identified as anti-N antibody by several methods. First, absorption of anti-N sera with goat anti-mouse immunoglobulin serum, but not normal goat serum, removed the activity. Second, radioimmuno-precipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of sucrose density gradient-fractionated anti-N sera showed that antiviral activity was present only in the fraction containing anti-N antibody. Finally, absorption of anti-N sera with insect cells infected with a baculovirus expressing the N protein removed the protective activity. These data indicate that anti-N antibody is a component of the resistance to rabies virus infections.     

Mutations in the E1 hydrophobic domain of rubella virus impair virus infectivity but not virus assembly

Rubella virus (RV) virions contain three structural proteins, a capsid protein that interacts with viral genomic RNA to form a nucleocapsid and two membrane glycoproteins, E2 and E1. We found that substitution of either an aspartic acid residue at Gly93 (G93D) or a glycine residue at Pro104 (P104G) in the internal hydrophobic domain of E1 affected virus infectivity but not virus assembly. Viruses carrying G93D and P104G mutations had impaired infectivity, reduced 1,000-fold and 10-fold, respectively. A revertant was isolated from the G93D mutant. Sequencing analysis showed that the substituted aspartic acid residue in G93D mutant had reverted to the original glycine residue, suggesting the involvement of Gly93 in membrane fusion during viral entry.     

Prevalence of GB virus C/hepatitis G virus in Hungary

In 1995 a new flavivirus, GB virus C/hepatitis G virus (GBV-C/HGV), was discovered. The aim of this study was to determine the prevalence of the virus in healthy persons and hepatitis patients in Hungary. The sera of 408 healthy persons older than 60 years were tested for the presence of GBV-C/HGV antibodies, and 113 were positive (28%). Eight of the 71 healthy persons younger than 60 years and twenty of the 51 sera (39%) taken from patients suffering from hepatitis of unknown origin proved to be positive for GBV-C/HGV antibodies. Ten of the 124 sera (8%) of healthy persons and 36 of the 247 sera (14.6%) of hepatitis patients proved to be positive for GBV-C/HGV RNA. Eleven PCR products were sequenced, and the sequences were found to be different from each other and from the previously published ones. However, three sequences taken from the same patient at different times were identical. These results show that GBV-C/HGV is present in Hungary and cannot be considered rare.     

基于流行性感冒病毒保守区域的通用流行性感冒疫苗的研究进展

流行性感冒(流感)疫情频频暴发,严重危害人类健康和公共卫生。虽然接种流感疫苗能够起到有效的预防作用,但由于流感病毒易变异,使得流感疫苗只对疫苗株或与疫苗株高度相近的病毒株具有保护效果。因此,研制一种可抵御不同型或亚型流感病毒的通用疫苗成为流感疫苗研究的热点。现就基于流感病毒保守区域的通用流感疫苗的研究进展作一综述。     

Hepatitis B virus exposure in human immunodeficiency virus seropositive Cuban patients

In order to estimate the prevalence of serological markers of exposure to Hepatitis B Virus (HBV), 295 subjects were selected at random from the National Registry of human immunodeficiency virus positive subjects. Evidence of exposure to HBV was defined as: testing Hepatitis B surface antigen (HBsAg) and anti-Hepatitis B core antigen (anti-HBc) positive or anti-HBc positive only. Overall, 133 (45.5%) were positive for anti-HBc and 15 (5.1%) resulted positive to HBsAg. Significant statistical association was found between male sex and exposure to HBV (p<0.01). Homosexual or bisexual behavior was found to be strongly associated to HBV exposure (p<0.001). In conclusion, the prevalence of HBV serological markers is higher in Cuban HIV positive subjects compared to the Cuban general population.     

嵌合病毒技术在黄热病毒属病毒研究中的应用

嵌合病毒技术是用于RNA病毒研究的一个重要技术,近十年来在黄热病毒属病毒的研究中,构建了一些型内及型间的嵌合病毒,不仅有利于该属病毒的分子机制研究,更重要的是研制出一些新型减毒活疫苗.本文简单介绍该技术的原理、构建、影响因素、应用前景等.     

Genetic analysis of Murine hepatitis virus nsp4 in virus replication

Coronavirus replicase polyproteins are translated from the genomic positive-strand RNA and are proteolytically processed by three viral proteases to yield 16 mature nonstructural proteins (nsp1 to nsp16). nsp4 contains four predicted transmembrane-spanning regions (TM1, -2, -3, and -4), demonstrates characteristics of an integral membrane protein, and is thought to be essential for the formation and function of viral replication complexes on cellular membranes. To determine the requirement of nsp4 for murine hepatitis virus (MHV) infection in culture, engineered deletions and mutations in TMs and intervening soluble regions were analyzed for effects on virus recovery, growth, RNA synthesis, protein expression, and intracellular membrane modifications. In-frame partial or complete deletions of nsp4; deletions of TM1, -2, and -3; and alanine substitutions of multiple conserved, clustered, charged residues in nsp4 resulted in viruses that were nonrecoverable, viruses highly impaired in growth and RNA synthesis, and viruses that were nearly wild type in replication. The results indicate that nsp4 is required for MHV replication and that while putative TM1, -2, and -3 and specific charged residues may be essential for productive virus infection, putative TM4 and the carboxy-terminal amino acids K(398) through T(492) of nsp4 are dispensable. Together, the experiments identify important residues and regions for studies of nsp4 topology, function, and interactions.     

Role for influenza virus envelope cholesterol in virus entry and infection

Enveloped viruses are highly dependent on their lipid envelopes for entry into and infection of host cells. Here, we have examined the role of cholesterol in the virus envelope, using methyl-beta-cyclodextrin depletion. Pretreatment of virions with methyl-beta-cyclodextrin efficiently depleted envelope cholesterol from influenza virus and significantly reduced virus infectivity in a dose-dependent manner. A nonenveloped virus, simian virus 40, was not affected by methyl-beta-cyclodextrin treatment. In the case of influenza virus, infectivity could be partially rescued by the addition of exogenous cholesterol. Influenza virus morphology, binding, and internalization were not affected by methyl-beta-cyclodextrin depletion, whereas envelope cholesterol depletion markedly affected influenza virus fusion, as measured by a specific reduction in the infectivity of viruses induced to fuse at the cell surface and by fluorescence-dequenching assays. These data suggest that envelope cholesterol is a critical factor in the fusion process of influenza virus.