Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “VIRUSES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed1991

Vaccinia virus recombinants expressing either the measles virus fusion or hemagglutinin glycoprotein protect dogs against canine distemper virus challenge.

cDNA clones of the genes encoding either the hemagglutinin (HA) or fusion (F) proteins of the Edmonston strain of measles virus (MV) were expressed in vaccinia virus recombinants. Immunofluorescence analysis detected both proteins on the plasma membranes of unfixed cells as well as internally in fixed cells. Immunoprecipitation of metabolically radiolabeled infected-cell extracts by using specific sera demonstrated a 76-kDa HA polypeptide and gene products of 60, 44, and 23 kDa which correspond to a MV F precursor and cleavage products F0, F1, and F2, respectively. Neither recombinant induced cell fusion of Vero cells when inoculated individually, but efficient cell fusion was readily observed upon coinfection of cells with both recombinants. Inoculation of dogs with the vaccinia virus-MV F recombinant (VV-MVF) did not give rise to detectable MV-neutralizing antibody. Inoculation of dogs with the vaccinia virus-MV HA recombinant (VV-MVHA) or coinoculation with both recombinants (VV-MVF and VV-MVHA) induced significant MV-neutralizing titers that were increased following a booster inoculation. Inoculation of dogs with the vaccinia virus recombinants or with MV failed to induce canine distemper virus (CDV)-neutralizing antibodies. Upon challenge with a lethal dose of virulent CDV, signs of infection were observed in dogs inoculated with (VV-MVF). No symptoms of disease were observed in dogs that had been vaccinated with VV-MVHA or with VV-MVHA and VV-MVF and then challenged with CDV. All dogs vaccinated with the recombinant viruses as well as those inoculated with MV or a vaccine strain of CDV survived CDV challenge.

Animals↗
PubMed1995

Quantitative measurement of paramyxovirus fusion: differences in requirements of glycoproteins between simian virus 5 and human parainfluenza virus 3 or Newcastle disease virus.

To compare the requirements for paramyxovirus-mediated cell fusion, the fusion (F) and hemagglutinin-neuraminidase (HN) glycoproteins of simian virus 5 (SV5), human parainfluenza virus 3 (HPIV-3), and Newcastle disease virus (NDV) were expressed individually or coexpressed in either homologous or heterologous combinations in CV-1 or HeLa-T4 cells, using the vaccinia virus-T7 polymerase transient expression system. The contribution of individual glycoproteins in virus-induced membrane fusion was examined by using a quantitative assay for lipid mixing based on the relief of self-quenching (dequenching) of fluorescence of the lipid probe octadecyl rhodamine (R18) and a quantitative assay for content mixing based on the cytoplasmic activation of a reporter gene, beta-galactosidase. In these assays, expression of the individual F glycoproteins did not induce significant levels of cell fusion and no cell fusion was observed in experiments when cells individually expressing homologous F or HN proteins were mixed. However, coexpression of homologous F and HN glycoproteins resulted in extensive cell fusion. The kinetics of fusion were found to be very similar for all three paramyxoviruses studied. With NDV and HPIV-3, no cell fusion was detected when F proteins were coexpressed with heterologous HN proteins or influenza virus hemagglutinin (HA). In contrast, SV5 F protein exhibited a considerable degree of fusion activity when coexpressed with either NDV or HPIV-3 HN or with influenza virus HA, although the kinetics of fusion were two- to threefold higher when the homologous SV5 F and HN proteins were coexpressed. Thus, these data indicate that among the paramyxoviruses tested, SV5 has different requirements for cell fusion.

Animals↗
PubMed1995

Mokola virus glycoprotein and chimeric proteins can replace rabies virus glycoprotein in the rescue of infectious defective rabies virus particles.

A reverse genetics approach which allows the generation of infectious defective rabies virus (RV) particles entirely from plasmid-encoded genomes and proteins (K.-K. Conzelmann and M. Schnell, J. Virol. 68:713-719, 1994) was used to investigate the ability of a heterologous lyssavirus glycoprotein (G) and chimeric G constructs to function in the formation of infectious RV-like particles. Virions containing a chloramphenicol acetyltransferase (CAT) reporter gene (SDI-CAT) were generated in cells simultaneously expressing the genomic RNA analog, the RV N, P, M, and L proteins, and engineered G constructs from transfected plasmids. The infectivity of particles was determined by a CAT assay after passage to helper virus-infected cells. The heterologous G protein from Eth-16 virus (Mokola virus, lyssavirus serotype 3) as well as a construct in which the ectodomain of RV G was fused to the cytoplasmic and transmembrane domains of the Eth-16 virus G rescued infectious SDI-CAT particles. In contrast, a chimeric protein composed of the amino-terminal half of the Eth-16 virus G and the carboxy-terminal half of RV G failed to produce infectious particles. Site-directed mutagenesis was used to convert the antigenic site III of RV G to the corresponding sequence of Eth-16 G. This chimeric protein rescued infectious SDI-CAT particles as efficiently as RV G. Virions containing the chimeric protein were specifically neutralized by an anti-Eth-16 virus serum and escaped neutralization by a monoclonal antibody directed against RV antigenic site III. The results show that entire structural domains as well as short surface epitopes of lyssavirus G proteins may be exchanged without affecting the structure required to mediate infection of cells.

Antigens, Viral↗
PubMed1992

Virus-induced loss of class I MHC antigens from the surface of cells infected with myxoma virus and malignant rabbit fibroma virus.

Shope fibroma virus (SFV) is a leporipoxvirus that causes localized benign fibromas in immunocompetent adult rabbits that spontaneously regress due, in part, to a cell-mediated immune response. Myxoma virus (MYX) and malignant rabbit fibroma virus (MRV) are related leporipoxviruses that induce rapidly lethal generalized infections accompanied by tumors and immunosuppression. Because only these latter two viruses are known to compromise cell-mediated antiviral responses, cell surface levels of class I MHC molecules in SFV-, MRV-, and MYX-infected cells were investigated by fluorescent activated cell sorting analysis using a variety of different anti-HLA mAb. After infection with MYX or MRV there is a rapid decrease in the levels of detectable surface class I epitopes as detected by each antibody and by 24 h postinfection class I MHC Ag levels at the cell surface approach the level of background fluorescence observed with control antibodies. In contrast, only a moderate class I decrease is seen during infection with either SFV or vaccinia virus, an orthopoxvirus that is neither tumorigenic nor immunosuppressive. Surface class I marker loss induced by MYX and MRV is not simply due to nonspecific inhibition of total cellular protein synthesis by the viruses because class I levels decrease much further than the extent measured by estimating surface marker turnover in the presence of the protein synthesis inhibitor cycloheximide. Thus the loss of cellular surface class I molecules greatly exceeds the drop in level caused by complete blockage of host cell gene expression, and must involve removal or masking of preexisting class I epitopes from the cell surface by MRV/MYX. Cell surface levels of the transferrin receptor are unaffected by MYX and MRV infection, suggesting the observed class I decrease is not a nonspecific effect on total cell surface glycoproteins. Analysis of cells infected with MRV/MYX in the presence of cycloheximide or of cytosine arabinoside, an inhibitor of poxviral DNA replication, indicates that the class I marker loss is mediated in part by one or more viral late gene products. A probable explanation is that MRV/MYX late protein(s) interact with the class I MHC complex to either physically sequester these away from the cell surface and inhibit their recycling or else induce a conformational change that precludes recognition by all class I antibodies tested. In either event, we propose that such a major perturbation of the class I MHC complex would likely downregulate the class I-mediated presentation of viral Ag required to initiate cell-mediated immunity to these viruses.

Animals↗
PubMed1987

Infection of the central nervous system of mice by standard Sendai virus, defective interfering Sendai virus and the mixture of both: comparison of virus multiplication and pathogenicity.

The intracerebral (i.c.) infection of newborn mice with standard Sendai virus (SV), defective interfering Sendai virus (DV) and their mixture (SV + DV) has been used as a model for the possible role of defective interfering particles of paramyxoviruses in several chronic degenerative diseases of central nervous system (CNS). The dynamics of Sendai virus multiplication and virus distribution in CNS of mice, as well as the histological changes and the clinical symptoms were evaluated for up to 112 days post-infection (p.i.). The infectious virus was detected in the brains of animals inoculated i.c. either with SV, or DV, or SV + DV as soon as by 5 hr p.i., with maximum infectivity titre at 24 hr p.i. In brains of animals inoculated with SV, the virus was detected until 5th day p.i.; nevertheless in those, inoculated with SV + DV or DV, low infectious titres could be detected even at later intervals. In mice inoculated i.c. with DV, traces of Sendai virus were detected in subpassages, as late as 3 months p.i.

Animals↗
PubMed1984

Prevalence of antibodies to bovine respiratory syncytial virus, bovine viral diarrhea virus, bovine herpesvirus-1, and bovine parainfluenza-3 virus in sheep and goats in Quebec.

Serum samples were collected from 1,075 clinically normal sheep and goats from 77 flocks in 7 agricultural regions of Quebec from June to August 1982. Sheep and goats were tested for antibodies to bovine respiratory syncytial virus, bovine viral diarrhea virus, and bovine herpes-virus-1 by the indirect fluorescent antibody technique and for parainfluenza-3 virus by the hemagglutination inhibition test. The prevalence of antibodies in animals to respiratory syncytial virus was 31%; to bovine viral diarrhea virus, 22.2%; to bovine herpesvirus-1, 10.8%; and to parainfluenza-3 virus, 23.2%. Antibodies prevailed in similar proportions in young (less than 1 year) and adult (greater than 1 year) animals.

Animals↗
PubMed2002

Mucosal immunization of rhesus monkeys against respiratory syncytial virus subgroups A and B and human parainfluenza virus type 3 by using a live cDNA-derived vaccine based on a host range-attenuated bovine parainfluenza virus type 3 vector backbone.

Reverse genetics was used to develop a two-component, trivalent live attenuated vaccine against human parainfluenza virus type 3 (HPIV3) and respiratory syncytial virus (RSV) subgroups A and B. The backbone for each of the two components of this vaccine was the attenuated recombinant bovine/human PIV3 (rB/HPIV3), a recombinant BPIV3 in which the bovine HN and F protective antigens are replaced by their HPIV3 counterparts (48). This chimera retains the well-characterized host range attenuation phenotype of BPIV3, which appears to be appropriate for immunization of young infants. The open reading frames (ORFs) for the G and F major protective antigens of RSV subgroup A and B were each placed under the control of PIV3 transcription signals and inserted individually or in homologous pairs as supernumerary genes in the promoter proximal position of rB/HPIV3. The level of replication of rB/HPIV3-RSV chimeric viruses in the respiratory tract of rhesus monkeys was similar to that of their parent virus rB/HPIV3, and each of the chimeras induced a robust immune response to both RSV and HPIV3. RSV-neutralizing antibody titers induced by rB/HPIV3-RSV chimeric viruses were equivalent to those induced by infection with wild-type RSV, and HPIV3-specific antibody responses were similar to, or slightly less than, after infection with the rB/HPIV3 vector itself. This study describes a novel vaccine strategy against RSV in which vaccine viruses with a common attenuated backbone, specifically rB/HPIV3 derivatives expressing the G and/or F major protective antigens of RSV subgroup A and of RSV subgroup B, are used to immunize by the intranasal route against RSV and HPIV3, which are the first and second most important viral agents of pediatric respiratory tract disease worldwide.

Animals↗
PubMed1995

Quantification of whole virus particles (146S) of foot-and-mouth disease virus in the presence of virus subunits (12S), using monoclonal antibodies in a sandwich ELISA.

This paper describes a method for the specific quantification of whole virions of foot-and-mouth disease (146S) in the presence of virus subunits (12S). The method involves the use of virus neutralising monoclonal antibodies directed against a linear epitope of the VP1 loop region of a type O virus. The monoclonal antibodies were used as both capture and detecting reagents (labelled with horse radish peroxidase) in a sandwich ELISA. Such monoclonal antibodies also have the advantage that they do not detect viruses containing proteolytically cleaved VP1, thus the assay system is ideal for estimation of whole particles in vaccine manufacture where the immunogenicity of the vaccine depends on virus integrity (whole virions being present) and uncleaved capsid protein. VP1. Other combinations of different anti-type O FMD virus monoclonal antibodies used as capture and detecting reagents were also examined. The system could be adapted to on-line continuous testing of virus being produced during a manufacturing run allowing maximisation of virus yield and quality control.

Animals↗
PubMed1985

Virus myocarditis: molecular hybridization allows the detection of virus-RNA in heart muscle after virus infection.

In most patients with virus myocarditis, the diagnosis is still based on clinical data alone. Endomyocardial biopsies subjected to electron microscopy, immunofluorescence techniques and virus isolation procedures provide additional, but only occasionally conclusive information. In this communication we describe a new method which could possibly be used to improve the diagnostic possibilities in patients with suspected virus myocarditis. The method is based on the hybridization of radioactive complementary nucleotide sequences to virus-RNA. It is shown that in an experimental model (reovirus infected baby mice) this method can be used to demonstrate the virus infection of cardiac muscle. It is suggested that the method could be adapted to other viruses (e.g. coxsackie virus) and to endomyocardial biopsies derived from patients with suspected virus myocarditis.

Animals↗
PubMed1995

Vertical transmission of human immunodeficiency virus type 1: autologous neutralizing antibody, virus load, and virus phenotype.

OBJECTIVE: To evaluate immunologic and virologic correlates of vertical transmission of human immunodeficiency virus type 1 (HIV-1). DESIGN: Case-control study. PATIENTS: Women who were prospectively enrolled in a natural history study of HIV-1 infection in women and infants. Sixteen HIV-1-infected women whose infants became infected were matched by CD4+ cell percentage and use of zidovudine during pregnancy with women whose infants did not become infected. MEASUREMENTS: Maternal autologous neutralizing antibody, virus load determined by RNA-polymerase chain reaction (RNA-PCR), and virus phenotype. RESULTS: Most women in both groups had low titers of autologous neutralizing antibody, and no difference in neutralizing titers was observed (range, < 4 to 181 in both groups). The HIV-1 copy number in maternal plasma was not significantly different in the two groups but was inversely correlated with maternal CD4+ cell percentage (p < 0.005). Five women in the transmitting group and four in the non-transmitting group had syncytium-inducing (SI) phenotype virus. Two infected infants had SI phenotype virus. The SI phenotype virus was associated with a greater HIV-1 copy number in maternal plasma (p < 0.05) and an increase in the mortality rate for the infants (p < 0.01). CONCLUSIONS: In women matched for CD4+ cell percentage, low titers of autologous neutralizing antibody, high virus load, and SI phenotype virus were not associated with an increased risk of transmission of HIV-1 to their infants.

Acquired Immunodeficiency Syndrome↗
PubMed1956

Studies on host-virus interactions in the chick embryo-influenza virus system. XIV. The relation between tissue-bound and liberated virus materials under various conditions of infection.

Studies have been reported concerning the relationships between virus materials found in the allantoic membranes and media of eggs deembryonated after injection of Standard (ST), heat-inactivated (37 degrees C.) standard (DeltaST), and undiluted passage (UP) seeds. It was found that the membranes always contained relatively more non-infectious hemagglutinins (NIHA) than the media and, correspondingly, the ratios between infectious virus and hemagglutinin units (ID(50)/HA) in the tissues were up to 1.5 log(10) units lower than in the liberated progeny. These differences were seen not only following inoculation of undiluted ST, DeltaST, and UP seeds, the progenies of which always contain considerable proportions of NIHA, but also when dilute ST inocula were employed which lead to the liberation of only infectious virus. Essentially similar differences in the ID(50)/HA ratios were observed also in the allantoic membranes and fluids obtained from growth curve experiments in the intact chick embryo employing the various types of seeds. In correlating the liberated virus materials in the media of deembryonated eggs to those in the membranes it was noted that in any given 2 hour interval during the phase of nearly constant production and release up to 10 times the quantity of infectious virus was shed as was present in the tissues at the onset of that period. In contrast, only about (1/4) of the hemagglutinins were released during the same time. The viral (V) and soluble (S) complement-fixing antigens were found in the tissues but no detectable quantities were released during any 2 hour interval. The NIHA in the membranes apparently is located within the cells since it could not be released by the action of RDE. Intracellular inhibitors of hemagglutination were readily inactivated following inoculation of undiluted ST, DeltaST, or UP seeds but not when ultraviolet-inactivated virus was used. The inhibitor activity decreased in proportion to the hemagglutinins produced. Transfer of infected deembryonated eggs to the cold room after production and liberation of progeny were well under way immediately halted further release but in the tissues the status quo was maintained and release was resumed on return to the 37 degrees C. incubator. The addition of potassium cyanide to the medium of deembryonated eggs at 37 degrees C. during the period of nearly constant production and release of virus material reduced immediately and to comparable extents the ID(50) and HA titers in the tissues and liberation decreased in proportion. On removal of the cyanide 2 hours later, both titers in the tissues gradually returned to those of the untreated control eggs with a corresponding increase in liberation. The ID(50)/HA ratios were not affected by these manipulations. It is concluded that the NIHA in the membranes forms part of a dynamic process. An attempt has been made in the discussion to integrate the present results with previous observations concerning the formation of incomplete forms of virus and their nature and role in the infectious process.

Orthomyxoviridae↗
PubMed1967

Experimental transmission of influenza virus infection in mice. IV. Relationship of transmissibility of different strains of virus and recovery of airborne virus in the environment of infector mice.

A mouse-adapted Jap. 305 strain of influenza A(2) virus was found to be much more readily transmitted from one mouse to another than the NWS strain of influenza A(0) virus although the two viruses were equally pathogenic for mice as judged by pulmonary virus titers and lung lesions. The survival of artificially created aerosols of virus and the quantity of airborne virus required to initiate infection in mice were identical for the two viruses. The difference in transmissibility was associated with the recovery of infectious airborne virus in the environment of mice infected with the Jap. 305 strain during the period of their maximum infectiousness, but not in the environment of mice infected with the NWS strain.

Air Microbiology↗
PubMed1999

Structural similarities between influenza virus matrix protein M1 and human immunodeficiency virus matrix and capsid proteins: an evolutionary link between negative-stranded RNA viruses and retroviruses.

The evolutionary relationship of retroviruses to the negative-stranded RNA virus superfamily was examined by comparing protein structures. Since protein structures are more conserved over time than primary protein sequences, three-dimensional structural comparisons permit the identification of evolutionary relationships that were previously undetected. Human immunodeficiency virus (HIV) and influenza virus were used as representatives of the virus groups, and proteins with similar functions were compared. Since M1 of influenza virus has membrane- and RNA nucleocapsid-binding activities that are functionally analogous to those of the HIV matrix and capsid proteins, the structural similarities between these proteins were determined. Sequence alignments were based on superimposition of the three-dimensional structures. Helices 2, 2', 3 and 4 of the HIV matrix protein aligned and superimposed with the four-helix bundle of the membrane-binding N domain of M1 with a root mean square (RMS) of 3.48 A. Helices A, B and C of the HIV N-terminal capsid protein aligned and superimposed with three helices of the four-helix bundle of the RNA-binding N domain of M1 with an RMS of 2.63 A. The HIV Gag protein and influenza virus matrix protein may have evolved from a common ancestor protein. The similarities between influenza virus M1 and HIV matrix and capsid proteins may indicate an evolutionary link between retroviruses and negative-sense RNA viruses.

Amino Acid Sequence↗
PubMed1999

GB virus C/hepatitis G virus infection in HIV infected patients with haemophilia despite treatment with virus inactivated clotting factor concentrates.

AIM: To determine the frequency of GB virus C (GBV-C)/hepatitis G virus (HGV) infection before and after switch to the use of virus inactivated concentrates in haemophiliac patients infected with human immunodeficiency virus (HIV). PATIENTS AND METHODS: Initial and follow up sera from 49 children with haemophilia were analysed for the presence of GBV-C/HGV RNA and antibodies to HGV (anti-HGV). All patients had been infected with HIV while receiving concentrates without virus inactivation before 1984 and were subsequently treated with virus inactivated concentrates. RESULTS: In the first available serum sample (1987 or later), two of 49 patients were GBV-C/HGV RNA positive and two further patients were anti-HGV positive. During follow up (mean, 6 years), 14 patients developed markers of GBV-C/HGV infection. Eleven of these had received no blood products except clotting factor concentrates that had been prepared with virus inactivation. CONCLUSIONS: Despite being treated with virus inactivated clotting factor concentrates, HIV positive patients with haemophilia are at an increased risk of manifesting GBV-C/HGV infection. We hypothesise that GBV-C/HGV is transmitted by these clotting factor concentrates. However, we cannot rule out the emergence of markers of GBV-C/HGV infection as a result of the progression of immune impairment in the course of HIV infection.

Adolescent↗
PubMedDate not supplied

Cross-protection between Tacaribe complex viruses. Presence of neutralizing antibodies against Junin virus (Argentine hemorrhagic fever) in guinea pigs infected with Tacaribe virus.

Cross-protection between Junin virus and five other Tacaribe complex viruses and the serological response of guinea pigs inoculated with Tacaribe virus are reported here. Previous infection with Tamiami or Pichinde viruses significantly delayed guinea pig deaths. A 58% survival rate was found among animals immunized with three doses of Amapari virus, while guinea pigs inoculated with one dose of Machupo or Tacaribe virus were fully protected against Junin virus. Neutralization tests performed in serum samples of guinea pigs immunized with five doses of Tacaribe virus showed that they developed monologous and heterologous neutralizing antibodies.

Animals↗
PubMed1971

Antigenic and morphological similarities of progressive pneumonia virus, a recently isolated "slow virus" of sheep, to visna and maedi viruses.

Progressive pneumonia virus, the causative agent of a slow, pulmonary disease of Montana sheep, was shown to be antigenically related to two other slow viruses of sheep, visna and maedi. Electron microscopic examination of infected cells revealed that the virus matures by a budding process and that the budding particles as well as the mature, extracellular virions bear striking resemblances to the oncogenic ribonucleic acid (RNA) viruses. Recent findings of an RNA-dependent deoxyribonucleic acid polymerase associated with the virions of this group of slow viruses lend further support to the notion that they may tentatively be classified with the oncogenic RNA tumor viruses.

Animals↗
PubMed1975

Aberrant viruses in cells infected with murine sarcoma virus-feline leukemia virus.

This study describes an unusual type of virus seen when a feline leukemia virus (FeLV) pseudotype of murine sarcoma virus (MuSV) obtained by cocentrifugation procedures infected feline embryo cells (FEF) and two Crandell cat cell lines (CrFK1, CrFK2). When all three cell cultures were infected with MuSV-FeLV, only FEF and CrFK2 were transformed and only these showed normal and aberrant virus. The CrFK1 infected with MuSV-FeLV did not transform but did replicate normal type-C virus with a 50-A intermediate coat. The virus replicated in the two transformed lines showed three particles; a normal particle with a 50-A intermediate coat, a normal particle with a 100-A intermediate coat, and an aberrant particle with a 100-A intermediate coat.

Animals↗
PubMed1983

Cell-free translation of Drosophila C virus RNA: identification of a virus protease activity involved in capsid protein synthesis and further studies on in vitro processing of cricket paralysis virus specified proteins.

Drosophila C virus RNA acted as mRNA in rabbit reticulocyte lysates and directed the synthesis of at least one capsid protein and a number of higher molecular weight proteins. Kinetic analysis by pulse-chase experiments showed that a number of high molecular weight products acted as precursors to the capsid protein(s). Various dilution experiments were performed which showed that the virus specified a protease activity essential for the correct processing of precursors to give the capsid protein(s). A similar result was obtained with Cricket paralysis virus, and mixing experiments showed that the protease activity specified by one virus could perform some of the cleavages resulting in the production of the capsid proteins of the other virus. Some of the cleavages involving the highest molecular weight precursors could not be performed by the protease activity of the other virus. We could find no evidence for intramolecular cleavage of the capsid precursors of either of the viruses.

Animals↗