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Results for “Viral Structures”

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PubMed1991

NS2 protein of influenza virus is found in purified virus and phosphorylated in infected cells.

Purified viral preparations of influenza A virus were examined for the presence of NS2 protein hitherto considered as a viral nonstructural protein that is present only in infected cells. Analysis of purified virus by radioimmunoprecipitation with monospecific antisera to NS2 revealed its presence in the virus particle suggesting that it is a viral structural protein. NS2 protein was also shown to be phosphorylated in infected cells in this study. This brings the number of influenza virus phosphoproteins to three which include NP, NS1, and NS2. These observations raise important questions about the role of NS2 in the replication of influenza virus.

Capsid↗

PubMed2006

Filovirus assembly and budding.

Filoviruses belong to the order of negative-stranded non-segmented RNA viruses and are classified into two genera, Ebola and Marburg viruses. They have a characteristic filamentous shape, which is largely determined by the matrix protein VP40. Although VP40 is the main driving force for assembly and budding from the host cell, the production of infectious virus involves an intricate interplay between all viral structural proteins in addition to cellular factors, e.g., those that normally function in multi-vesicular body biogenesis. As a consequence, assembly and budding steps are defined to specific cellular compartments, and the recent progress in understanding how the different components are assembled into stable enveloped virus particles is reviewed.

Animals↗

PubMed1983

The human T-cell leukemia/lymphoma virus, lymphoma, lytic bone lesions, and hypercalcemia.

The human T-cell lymphoma (HTL) virus is a type C RNA tumor virus isolated from patients with malignancies of mature T cells. We report three patients with peripheral T-cell lymphoma, hypercalcemia, and antibodies to HTL virus. One patient presented with idiopathic hypercalcemia of 6 months' duration, two with striking lytic bone lesions, and two with circulating malignant lymphocytes. Malignant cells from all patients had surface markers characteristic of thymic-derived lymphocytes (T cells), and all patients had natural serum antibodies to disrupted HTL virus and to one or both viral structural proteins p19 and p24. Patients with adult peripheral T-cell lymphomas, particularly those that present with hypercalcemia and lytic bone lesions, may have antibodies to the type C RNA human tumor virus, HTL virus.

Adult↗

PubMed2003

The structure analysis and antigenicity study of the N protein of SARS-CoV.

The Coronaviridae family is characterized by a nucleocapsid that is composed of the genome RNA molecule in combination with the nucleoprotein (N protein) within a virion. The most striking physiochemical feature of the N protein of SARS-CoV is that it is a typical basic protein with a high predicted pI and high hydrophilicity, which is consistent with its function of binding to the ribophosphate backbone of the RNA molecule. The predicted high extent of phosphorylation of the N protein on multiple candidate phosphorylation sites demonstrates that it would be related to important functions, such as RNA-binding and localization to the nucleolus of host cells. Subsequent study shows that there is an SR-rich region in the N protein and this region might be involved in the protein-protein interaction. The abundant antigenic sites predicted in the N protein, as well as experimental evidence with synthesized polypeptides, indicate that the N protein is one of the major antigens of the SARS-CoV. Compared with other viral structural proteins, the low variation rate of the N protein with regards to its size suggests its importance to the survival of the virus.

Amino Acid Motifs↗

PubMed1988

Functional replacement of the HIV-1 rev protein by the HTLV-1 rex protein.

Two evolutionarily distinct families of human retroviruses, the human immunodeficiency viruses (HIV) and the human T-cell leukaemia viruses (HTLV), have been defined (reviewed in ref. 1). Although these virus groups share tropism for human CD4+ T cells, they differ markedly in primary sequence, genetic organization and disease association (AIDS versus adult T-cell leukaemia), but show similar general strategies for the regulation of viral gene expression. Each encodes a protein able to trans-activate transcription from the homologous viral long terminal repeat (tat in HIV, tax in HTLV), although these proteins act by different mechanisms and do not appear to be interchangeable. Each virus also produces a second trans-acting protein that induces the expression of the unspliced messenger RNAs encoding the viral structural proteins (rev in HIV and rex in HTLV). Here we show that the rex protein of HTLV-I can functionally replace the rev protein of HIV-1 in transient expression assays. This genetic complementation by rex is adequate for the rescue of a replication-defective rev mutant of HIV-1. This unexpected shared function between the structurally distinct rex and rev proteins emphasizes the importance of this highly conserved pathway for the regulation of human retrovirus gene expression.

Gene Expression Regulation↗

PubMed1995

New isolates of pneumonia virus of mice (PVM) from Japanese rat colonies and their characterization.

Two virus strains were isolated from the lungs of athymic rats and mice used as sentinel animals in 2 colonies of laboratory rats in Japan in which antibodies to the pneumonia virus of mice (PVM) had been detected. The new isolates were identified as PVM by the following characteristics: RNA virus, susceptibility to ether treatment, long filamentous viral structure in the cytoplasm of infected cells, and hemagglutinating activity in various erythrocytes, including those of mice and rats. In addition, cross neutralization with the prototype of PVM (No. 15 strain) was observed. This is the first report of the isolation of PVM from laboratory animals in Japan.

Animals↗

PubMed1999

Filamentous intranuclear inclusion bodies in psittacine birds. A structural and ultrastructural study.

This paper concerns a disease affecting a group of African grey parrots, which involves intranuclear inclusion bodies composed of filamentous material. The disease was characterized by either sudden death or death within 2-3 days from onset of non-specific symptoms. At necropsy, gross lesions included enlarged liver, mild hepatic congestion and focal necrosis. Samples from five birds were fixed in 10% formol and routinely processed for light and electron microscopy. In four birds, numerous hepatocytes displayed an enlarged nucleus, with peripheral margination of chromatin; the nucleus was partially or wholly filled by a basophilic inclusion body. In the remaining bird, inclusion bodies were acidophilic and completely filled the nucleus; nuclear enlargement was less evident than in the other birds. At ultrastructural examination, and in both types of IIB, nuclei contained looped filaments but no evidence of viral structures. However, virion-like structures were observed in the cytoplasm of some hepatocytes.

Animals↗

PubMed1986

C-terminal region of human T cell lymphotropic virus type I (HTLVI) p19 core protein is immunogenic in humans and contains an HTLVI-specific epitope.

To study the human host response to viral structural proteins during HTLV type I infection, five synthetic peptides matching the N-terminal and C-terminal regions of HTLVI p19 core protein were used to identify antigenic sites on p19 that were immunogenic in man. In radioimmunoassay and immunoprecipitation experiments, antibodies in 16 of 18 HTLVI+ patient sera reacted with a synthetic peptide matching the C-terminal 11-amino acid sequence of p19, whereas only two sera contained antibodies that reacted with other N- or C-terminal region p19 synthetic peptides. Polyclonal rabbit antisera to N- and C-terminal peptides reacted with a native viral protein of 19,000 daltons and with gag-encoded precursors of p19. Six monoclonal antibodies against native viral p19 were screened for reactivity to the five synthetic peptides. One of six antibodies (13B12) reacted with the C-terminal synthetic peptide of p19. Antibody 13B12 did not react with HTLVII or HTLVIII proteins or with HTLVIII-infected cells, nor did it cross-react with a wide variety of HTLV-uninfected normal host tissues. Thus, the C-terminus of p19 contains an antigen that is highly immunogenic in most HTLVI-infected patients and is HTLVI specific.

Antibodies, Monoclonal↗

PubMed1986

[Contribution of modern research technics to the identification of a virus in Paget's disease of bone].

The morphological resemblance between osteoclast inclusions in Paget's bone disease and viral structures has encouraged new research with immunocytologic methods and In Situ hybridization. Paramyxovirus antigens of measles virus and respiratory syncitial virus were detected in pagetic osteoclasts using polyclonal antibodies. Paramyxovirus antigens of measles virus, simian virus (SV 5) and human parainfluenza virus (PF 3) were demonstrated using monoclonal and monospecific polyclonal antibodies. Measles virus nucleotide sequences were detected in pagetic osteoclasts by In Situ hybridization with a 3H labelled cDNA probe specific for measles nucleocapsid protein. However, the same probe also hybridized with several types of mononucleated cells suggesting a wide host range for measles virus genomic information. Apparently, this viral information is translated only in the osteoclasts. The link between the presence of viral information in pagetic bone tissue cells and Paget's disease itself still awaits elucidation.

Bone and Bones↗

PubMed1976

Adenovirus protein maturation at 42 degrees C.

Incubation of adenovirus type 2 infected cells at 42 degrees C resulted in an inhibition of assembly of virus particles although all the major viral structural polypeptides and virus-induced cellular polypeptides so far identified were detected by electrophoretic analysis. Selective high salt-acid-urea extraction of low mol. wt. polypeptides revealed the absence of protein VII at 42 degrees C whereas precursor polypeptide P-VII and core protein V were found. Pulse-chase and temperature shift experiments indicated that cleavage of P-VII into VII was a reversible thermosensitive process, requiring de novo protein synthesis after shift-down to 37 degrees C. Virus particles assembled at 37 degrees C after transfer from 42 to 37 degrees C contained both viral DNA and polypeptides pre-labelled during the eclipse phase at 42 degrees C, including core protein VII.

Adenoviridae↗

PubMed2001

Nuclear targeting of DNA.

The nuclear membrane is a tight barrier for cytoplasmic proteins, but nuclear proteins have the intrinsic ability to overcome this barrier by an active signal-mediated process. Specific cytoplasmic carrier proteins have the responsibility to escort these proteins into the nucleus through the nuclear pore. The nuclear membrane is also a tight barrier for exogenous DNA delivered by synthetic vehicles, while many of the karyophilic viruses have a mechanism to actively deliver their genome through the nuclear pore. Virus DNA and RNA cannot move into the nucleus by themselves and require the viral structural proteins for efficient nuclear transport. In this article, we review the recent progress in understanding the mechanism of the nuclear transport of proteins and the virus genome, and discuss the possibility of developing synthetic gene-delivery systems based on these outcomes.

Active Transport, Cell Nucleus↗

PubMed1987

Evidence for the expression of protein IX in some rat cells transformed with adenovirus type 12 early region 1 DNA.

Sera were produced by injection of a particular rat cell line (HLBRK EcoC1), produced by transformation of baby rat kidney cells with adenovirus 12 early region 1 DNA, into the syngeneic host. Antibodies to a protein of Mr 15,200 as determined by SDS-PAGE, were detected in the sera from two rats bearing tumours. The 15K protein was identified as the viral structural component polypeptide IX by a number of criteria: (i) the protein was only observed in adenovirus 12-infected cells, (ii) it was produced at intermediate and late times after infection, (iii) it was immunoprecipitated from purified adenovirus 12 particles and (iv) it was immunoprecipitated from a purified protein preparation.

Adenoviridae↗

PubMed2004

[Effect of cytomegalovirus strain selection on stimulation of cytokine panel Th1/Th2].

CMV infection can undergoing as primary or secondary infection, which can be represented by reactivation of endogenous infection or by superinfection with another viral strain. Taking for consideration high prevalence of seropositive persons it may be concluded that superinfections occur quite often. For the other hand it is known, that differences among CMV strains are deep and regard as well viral structure as its biological properties. The aim of this study was investigation of immunological profile in range of cytokines production after stimulation with different CMV strains. The study was conducted with leukocytes obtained from CMV seropositive person cultivated and stimulated in vitro with AD169, Towne and Davis. After 24, 48, 72 and 96 hours incubation concentrations of IL-2, IL-4, IL-5, IL-10, INF-gamma and TNF-alpha in supernatants was measured by flow cytometry with Cytometric Bead Array technique. Obtained results allow to conclude that difference in level of stimulated cytokines and their panel is dependent on viral strain used. The experiment also allows to optimisation of stimulation conditions.

Antibodies, Viral↗

PubMed1998

Viral proteins VP2, VP6, and NSP2 are strongly precipitated by serum and fecal antibodies from children with rotavirus symptomatic infection.

Rotavirus-specific IgA has been correlated with immune protection against rotavirus reinfection and symptomatic disease. Systemic and mucosal antibody responses were determined by an enzyme-linked immunosorbent assay in 11 infants with severe rotavirus gastroenteritis. Geometric mean titers of antirotavirus serum IgG and IgA antibodies were significantly higher during the convalescence of the disease (P < 0.001 vs. acute-phase titers). Rotavirus-specific fecal sIgA antibodies increased 4 times during the convalescence in 9 (81.8%) children (P < 0.001). The serum IgG and IgA antibody and fecal sIgA antibody responses to individual rotavirus polypeptides were characterized by radioimmunoprecipitation assay (RIPA) using Staphylococcus aureus protein A and the lectin jacalin to precipitate IgG- and IgA-immune complexes, respectively. The main IgG response was directed toward the structural viral proteins VP2, VP4, and VP6 and toward the nonstructural protein NSP2. Serum IgA reactivity was detected by RIPA in all serum samples, with major responses to VP2, VP6, and NSP2. Interestingly, fecal sIgA in convalescent samples reacted strongly toward NSP2 and VP6. These data reinforce the antigenic importance of rotaviral proteins other than VP4 and VP7, such as VP2, VP6, and NSP2, as main targets in the immune response to rotavirus.

Antibodies, Viral↗

PubMed1993

Ribozyme cleaves rex/tax mRNA and inhibits bovine leukemia virus expression.

Bovine leukemia virus (BLV) encodes at least two regulatory proteins, Rex and Tax. Tax, the transactivating protein, stimulates the long terminal repeat to promote viral transcription and may be involved in tumorigenesis. Rex is involved in the transition from early expression of regulatory proteins to later expression of viral structural proteins. We have targeted ribozymes against the mRNA encoding Rex and Tax. The ribozymes consist of the hammer-head catalytic motif flanked by antisense sequences that hybridize with the complementary rex/tax mRNA. To evaluate cleavage in a cell-free system, we transcribed portions of rex/tax mRNA and incubated them with synthetic RNA ribozymes. A ribozyme was identified that cleaves > 80% of the target RNA. Synthetic DNA encoding this ribozyme was cloned into the expression vector pRc/RSV and transfected into BLV-infected bat lung cells. Intracellular cleavage of rex/tax mRNA was confirmed by reverse transcriptase PCR. In cells expressing the ribozyme, viral expression was markedly inhibited. Expression of the BLV core protein p24 was inhibited by 61%, and reverse transcriptase activity in supernatant was inhibited by 92%. Ribozyme inhibition of BLV expression suggests that cattle expressing these sequences may be able to control BLV replication.

Animals↗

PubMed1988

Detection of human papillomavirus DNA sequences by in situ DNA-DNA hybridisation in cervical intraepithelial neoplasia and invasive carcinoma: a retrospective study.

Human papillomavirus (HPV) infection of cervical intraepithelial neoplasia (CIN) and invasive cervical carcinoma was investigated using in situ DNA-DNA hybridisation on histological sections of formalin fixed, paraffin embedded tissue to assess the technique's sensitivity and to assess retrospectively the association between HPV16 and invasive cervical carcinoma. HPV DNA was detected in 16 of 33 biopsy specimens of CIN. Cells containing viral DNA were more numerous than those positive for viral structural proteins. HPV DNA was also present in less differentiated cells deeper in the epithelium. The detection rate in CIN was lower than that reported for other hybridisation techniques such as Southern blotting. In a retrospective study of biopsy specimens of invasive squamous carcinoma of the cervix HPV16 DNA, the virus most commonly associated with cervical malignant disease, was found in 20 of 25 cases, including those dating from as far back as 1932. The level of sensitivity was similar to that reported for other hybridisation techniques. DNA positive cells were focally distributed in the invasive tumours, and most tumour cells were negative for viral DNA, a result consistent with the low copy number found in malignant cells. It is concluded that HPV16 is not a new virus but that its prevalence is a result of changes in sexual behaviour and that in situ hybridisation is useful in the localisation of HPV DNA replication in CIN and invasive carcinoma.

DNA, Viral↗

PubMed1979

A new endogenous primate type C virus isolated from the Old World monkey Colobus polykomos.

A new, genetically transmitted retrovirus has been isolated from the Old World monkey Colobus polykomos. This virus, designated CPC-1, is readily transmitted to both feline and human cells in culture. Nucleic acid hybridization studies reveal that there are 50-70 copies of the CPC-1 genome in colobus cellular DNA. Related virogene sequences can be detected in the DNA of all other Old World monkeys, as well as in the DNA of at least one ape species, the chimpanzee, indicating that this virus has been genetically transmitted in primates for 30-40 million years. CPC-1 is partially related to the type C virus previously isolated from stumptail monkeys (MAC-1). These two viruses have nucleic acid sequence homology, antigenic crossreactivity in their major viral structural protein, and a very similar host range in vitro. CPC-1 and MAC-1 therefore belong to the same class of genetically transmitted primate type C viruses and, as such, represent the first example in primates of analogous endogenous retroviruses isolated from two distantly related species.

Animals↗

PubMed1980

Antibody to the rheumatoid arthritis nuclear antigen. Its relationship to in vivo Epstein-Barr virus infection.

Most patients with seropositive rheumatoid arthritis, and a variable but lesser percentage of normal subjects, have precipitating antibodies to a nuclear antigen, rheumatoid arthritis nuclear antigen, present in Epstein-Barr virus-infected human B lymphoblastoid cells. We have used a sensitive indirect immunofluorescence assay for antibody to rheumatoid arthritis nuclear antigen in a study of patients with infectious mononucleosis and healthy control subjects. Of 110 sera from normal, college-age cadets, 58 were from individuals without prior Epstein-Barr virus infection, as indicated by the lack of antibody to viral capsid antigen. All of these also lacked activity to rheumatoid arthritis nuclear antigen. 52 sera were positive for antibody to viral capsid antigen, and antibody to rheumatoid arthritis nuclear antigen was present in 26 (50%) of these. In 67 sequential sera from 11 college-age students with infectious mononucleosis who became positive for antibody to rheumatoid arthritis nuclear antigen, only 2 were positive during the 1 mo. Thereafter the incidence and titers increased progressively through the 1st yr after infection. This time-course resembled that for the development of antibody to Epstein-Barr nuclear antigen, another transformation antigen in Epstein-Barr virus-infected B lymphocytes. The development of positivity for both was much later than that of antibody to the structural viral capsid antigen, which in the current study was always positive by 1 wk. Thus, antibody to rheumatoid arthritis nuclear antigen is present in a large proportion of normal individuals and can now be clearly ascribed, from both in vivo and in vitro studies, to prior infection with Epstein-Barr virus.

Antibodies, Antinuclear↗