Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Capsid”

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 1,765 records · Page 98Linked to original sources
PubMed2001

Generation of a high-capacity hybrid vector: packaging of recombinant adenoassociated virus replicative intermediates in adenovirus capsids overcomes the limited cloning capacity of adenoassociated virus vectors.

Gene therapy aims to complement or, ideally, correct defective genes. The broad clinical application of this emerging technology requires the development of safe high-capacity gene delivery vehicles that combine efficient transduction of dividing as well as quiescent cells with sustained transgene expression. Here we present a new hybrid vector system that unites favorable attributes of adenoassociated virus (AAV) and adenovirus (Ad) vectors in a single particle. This was achieved by inclusion of Ad packaging elements in different sized recombinant AAV genomes. In the presence of AAV replicative functions and a recombinant helper Ad, AAV/Ad hybrid particles were generated via encapsidation of AAV-dependent replicative intermediates into Ad capsids. In stringent in vitro models based on transduction of proliferating cells we show that AAV/Ad hybrid vectors are superior to Ad vectors in establishing prolonged transgene expression and can be used to deliver DNA fragments of at least 27 kb.

Adenoviruses, Human↗
PubMed2002

Hexagonal organization of Moloney murine leukemia virus capsid proteins.

To help elucidate the mechanisms by which retrovirus structural proteins associate to form virus particles, we have examined membrane-bound assemblies of Moloney murine leukemia virus (M-MuLV) capsid (CA) proteins. Electron microscopy and image reconstruction techniques showed that CA dimers appear to function as organizational subunits of the cage-like, membrane-bound protein arrays. However, new three-dimensional (3D) data also were consistent with hexagonal (p6) assembly models. The p6 3D reconstructions of membrane-bound M-MuLV CA proteins gave unit cells of a = b = 80.3 A, c = 110 A, gamma = 120 degrees, in which six dimer units formed a cage lattice. Neighbor cage hole-to-hole distances were 45 A, while distances between hexagonal cage holes corresponded to unit cell lengths (80.3 A). The hexagonal model predicts two types of cage holes (trimer and hexamer holes), uses symmetric head-to-head dimer building blocks, and permits the introduction of lattice curvature by conversion of hexamer to pentamer units. The M-MuLV CA lattice is similar to those formed in helical tubes by HIV CA in that hexamer units surround cage holes of 25-30 A, but differs in that M-MuLV hexamer units appear to be CA dimers, whereas HIV CA units appear to be monomers. These results suggest that while general assembly principles apply to different retroviruses, clear assembly distinctions exist between these virus types.

Capsid↗
PubMed2002

Characterization of neutralization specificities of outer capsid spike protein VP4 of selected murine, lapine, and human rotavirus strains.

Neutralization specificities of outer capsid spike protein VP4 of murine rotavirus strains EW (P?[16],G3) and EHP (P?[20],G3) and lapine rotavirus strains Ala (P?[14],G3), C11 (P?[14],G3), and R2 (P?[14],G3) as well as human rotavirus strains PA169 (P?[14],G6) and HAL1166 (P?[14],G8) were determined by two-way cross-neutralization. This was done by generating and characterizing (i) three murine x human, three lapine x human, and two human x human single gene substitution reassortant rotaviruses, each of which bore identical human rotavirus DS-1 strain VP7 (G2), and (ii) guinea pig hyperimmune antiserum raised against each reassortant. Reference rotavirus strains employed in the study represented 10 established VP4 (P) serotypes, including 1A[8], 1B[4], 2A[6], 3[9], 4[10], 5A[2], 5B[2], 5B[3], 6[1], 7[5], 8[11], 9[7], and 10[16] as well as a P serotype unknown P[18]. Murine rotavirus strains EW and EB were demonstrated to share the same P serotype (P10[16]) distinct from (i) 9 established P serotypes, (ii) lapine and human rotavirus strains bearing the P[14] genotype, and (iii) an equine rotavirus strain bearing the P[18] genotype. Both lapine (Ala, C11, and R2) and human (PA169 and HAL1166) rotaviruses were shown to belong to the same VP4 serotype, which represented a distinct new P serotype (P11[14]). P serotype 13[20] was assigned to murine rotavirus EHP strain VP4, which was shown to be distinct from all the P serotypes/genotypes examined in the present study.

Animals↗
PubMed2002

Construction of a novel JCV/SV40 hybrid virus (JCSV) reveals a role for the JCV capsid in viral tropism.

JC virus (JCV) is a common human polyomavirus that infects greater than 70% of the general population worldwide. JCV is also the causative agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the CNS. Currently, little is known about the mechanisms that restrict JCV tropism to a few human cell types and tissues. In vivo, JCV can be detected in oligodendrocytes and astrocytes in the CNS of patients with PML. The virus can also be detected in kidney, tonsil, and B lymphocytes of patients both with and without PML. In vitro, JCV can only be propagated in cultures of human fetal glial cells or in cell lines derived from this tissue. In contrast, the closely related monkey polyomavirus, SV40, has a broad tropism for primate cells, including those cells that are also susceptible to infection by JCV. We hypothesized that one potential block to infection is at the level of virus entry. To examine this, we constructed a JCV-SV40 chimeric viral genome that contains the regulatory region and the early genes of SV40 and the late structural genes of JCV. The hybrid virus (JCSV) induced SV40-like cytopathic effect in human glial cells and hemagglutinated human type O red blood cells similar to JCV. More importantly, the hybrid virus maintained the host range of JCV, suggesting that interactions between the virus capsid and host cell receptors contribute to JCV tropism.

Animals↗
PubMed2002

Sequence diversity of the capsid gene and the nonstructural gene NS2B of dengue-3 virus in vivo.

Previously, we studied the envelope (E) gene of dengue virus and reported that dengue-3 virus is present as a quasispecies. To investigate the extent of intrahost sequence variation of other dengue viral genes, we examined in this study the capsid (C) gene and the nonstructural gene, NS2B, derived directly from plasma dengue viruses from 18 confirmed dengue-3 patients. Using reverse transcription-PCR, multiple clones of a 360-nucleotide region covering the C gene and of a 404-nucleotide region covering the NS2B gene from each patient were completely sequenced and analyzed. Our findings of the intrahost sequence variation of the C and the NS2B genes (mean pairwise p-distance: 0.12 to 1.02%, and 0.16 to 1.20%, respectively) demonstrate the quasispecies structure of dengue virus in vivo. A linear relationship was found between the extent of sequence variation of the C and NS2B proteins, suggesting that intrahost sequence variation of dengue-3 virus is likely to reflect genetic drift. The extent of intrahost sequence variation observed is in the same range as that of acute human immunodeficiency virus or hepatitis C virus infection, indicating that the random mutation frequency of dengue virus is similar to that of other RNA viruses in vivo. Consistent with a previous report of the E gene, the observations of genome-defective clones in both the C and the NS2B genes (3.9 and 5.0% of the clones, respectively) suggest a higher frequency of defective viruses in vivo. These findings would add to our understanding of the evolution of dengue-3 virus.

Adult↗
PubMed1994

Use of drug-resistance mutants to identify functional regions in picornavirus capsid proteins.

The WIN drugs and similar hydrophobic compounds that insert into the capsid of picornaviruses have been shown to block viral uncoating. In some of the human rhinoviruses they also block attachment of virus to cells. Spontaneously occurring drug-resistant mutants of human rhinovirus 14 and poliovirus type 3 were selected for their ability to make plaques in the presence of the selecting drug. The HRV-14 mutants either prevented drug binding or allowed the virus to attach to cells in the presence of drug. About two thirds of the poliovirus mutants were dependent on the presence of drug for plaque formation. In single cycle growth curves, drug was not required for the formation of drug-dependent progeny virus. However, progeny virus grown without drug never accumulated outside of cells, thus making the formation of plaques impossible. This behavior was apparently caused by the extreme thermolability of these mutants. In the absence of drug, heating to 37 degrees C rapidly converted them to non-infectious particles with a sedimentation coefficient of 135S.

Antiviral Agents↗
PubMed1992

Antisense RNA directed against the major capsid protein of Lactococcus lactis subsp. cremoris bacteriophage 4-1 confers partial resistance to the host.

Antisense RNA targeted against the major capsid protein (MCP) of Lactococcus lactis subsp. cremoris bacteriophage F4-1 reduced bacteriophage replication by up to 50%. The region containing the mcp gene was oriented to transcribe the antisense strand using a L. lactis subsp. cremoris Wg2 promoter. The size of the mcp insert transcribed affected the level of bacteriophage inhibition and the greatest level of inhibition was achieved using a 301-bp fragment from the 5' end of the mcp. Antisense mcp RNA constructs were stable and did not alter the endogenous plasmid profile in the host, L. lactis subsp. cremoris F4-1. There were, however, some adverse effects on the host during the stationary phase as exhibited by a decline in cell density.

Bacteriophages↗
PubMed1984

The capsid antigen of Epstein-Barr virus in nasopharyngeal carcinomas: comparison of serum antibody titre, cellular antigen content and histopathology.

In a retrospective study of 21 patients with nasopharyngeal malignancies (lymphoepithelial carcinomas, both undifferentiated and dedifferentiated serological and immunohistological methods were used to examine the significance of the IgG- and IgM-antibody against the capsid antigen of Epstein-Barr virus for early detection and follow-up, and the findings compared with those from a control group. Furthermore, the IgA-antibody is taken into account and presented with examples from the literature. Other possible forms of therapy (combined radio- and polychemotherapy) are also discussed.

Antibodies, Viral↗
PubMed1988

Nucleotide sequence of the capsid protein gene of potato virus Y (PVY).

The nucleotide sequence of the 3' terminal region of potato virus Y (PVY) was determined. Starting with a poly(A) tail of 18 residues a non-coding region of 335 nucleotides precedes the region encoding for the virus coat protein (cp) 801 nucleotides long ending with a TGA. This region was located by comparing the predicted amino acid sequence with the one determined for the PVY capsid protein by Shukla et al. (1). Both sequences contained 267 amino acids sharing about 94% homology. They differ, however, at several positions presumably due to base transitions within their respective nucleotide sequences. Restriction endonuclease sites in and around the cp coding region were identified.

Base Sequence↗
PubMed1996

Semliki Forest virus capsid protein inhibits the initiation of translation by upregulating the double-stranded RNA-activated protein kinase (PKR).

We investigated the possible translational role which elevated concentrations of highly purified Semliki Forest virus (SFV) capsid (C)-protein molecules may play in a cell-free translation system. Here we demonstrate that in the absence of double-stranded RNA high concentrations of C protein triggered the phosphorylation of the interferon-induced, double-stranded RNA-activated protein kinase, PKR. Activated PKR in turn phosphorylated its natural substrate, the alpha subunit of eukaryotic initiation factor 2 (eIF-2), thereby inhibiting initiation of host cell translation. These findings were further strengthened by experiments showing that during natural infection with SFV the maximum phosphorylation of PKR coincided with the maximum synthesis of C protein 4-9 hours post infection. Thus, our results demonstrate that high concentrations of C-protein molecules may act in a hitherto novel mechanism on PKR to inhibit host cell protein synthesis during viral infection.

Capsid↗
PubMed1993

Cloning of the capsid protein gene from a blotch isolate of peanut stripe virus.

The 3' terminal 1,367 nucleotides (nts) of a blotch isolate of the potyvirus, peanut stripe virus (PStV), were cloned and sequenced. This region included the 861 nts (287 amino acids) of the PStV capsid protein (CP). The amino acid sequence of the predicted proteinase cleavage site was identified. This region shared limited homology with other potyvirus proteinase cleavage sites. The viral CP gene sequence was followed by 254 nucleotides of 3' nontranslated sequence and a poly-A tail. Based on computer modeling, the 3' nontranslated region could form two lengthy stem-loop structures and two pseudoknot structures. Subclones containing the coding sequences of the CP (amino acids 1-287, 17-287, 17-113 and 106-287) were constructed and expressed in Escherichia coli. These polypeptides were detected using polyclonal antibodies in Western blots.

Amino Acid Sequence↗
PubMed1993

Semliki Forest virus capsid protein expressed by a baculovirus recombinant.

We have constructed a recombinant baculovirus which expressed the Semliki Forest (SFV) capsid (C) gene as a fusion protein under the control of the polyhedrin gene promoter. The sequence coding for C and part of the envelope E3 region were expressed as a polyprotein precursor. Spodoptera frugiperda (Sf9) insect cells infected with the recombinant virus produced a protein reacting with polyclonal rabbit antiserum that had been raised against the 33 kDa authentic C protein purified from SFV. Primer extension analyses showed that transcription from the polyhedrin promoter started in the late/very late consensus initiation motif. Due to its autoprotease activity, the recombinant C protein was contranslationally cleaved within its C-terminus and the mature protein remained undegraded for long periods of time. Spodoptera frugiperda cells infected with recombinant virus synthesized large amounts of C protein. The recombinant protein was karyophilic as is authentic SFV C protein and it was translocated into the nucleus; there, it was associated with nucleolus-like structures.

Amino Acid Sequence↗
PubMed1992

Biological roles of the major capsid proteins and relationships between the two existing serotypes of infectious bursal disease virus.

Neutralizing monoclonal antibodies (n-MAbs) were produced against infectious bursal disease virus (IBDV) of serotypes 1 and 2. The n-MAbs recognizing the major antigenic proteins VP2 and VP3, were characterized using different strains of IBDV representing the existing two serotypes and a variant subtype of serotype 1. The biological properties of these viral antigens as defined by the MAbs in vitro, were studied utilizing post-adsorption virus neutralization tests and fluorescence-activated cell sorter analysis. The MAbs directed against the immunodominant epitopes on VP2 were capable of enhanced virus neutralization but did not inhibit the virus attachment to susceptible cells. These MAbs were able to neutralize the virus by interfering with an event subsequent to virus adsorption, possibly inhibiting virus penetration or uncoating. On the contrary, a MAb that immunoprecipitated the other capsid protein VP3 was able to prevent virus attachment although it possessed lower neutralization titers. Cross-immunoprecipitations of various virus strains by these MAbs and antisera revealed interrelationships between the two serotypes of IBDV.

Antibodies, Monoclonal↗
PubMed1985

Binding of neutralizing monoclonal antibodies to empty capsids of poliovirus can be blocked by monospecific antisera to structural polypeptides VP1 and VP2.

Binding of two neutralizing monoclonal antibodies (Nt-mAbs) to natural empty capsids (NEC) of poliovirus, type 1, was blocked to the extent of 83 per cent to 98 per cent by monospecific rabbit antisera directed against the structural polypeptides VP1 and VP2. Monospecific antisera against VP3 or VP4, however, did not show this blocking effect. It is therefore assumed that VP1 and VP2 are located close together at the antigenic sites for the two mAbs.

Antibodies, Monoclonal↗
PubMed1994

The nucleotide sequence of the 5'non-coding and capsid coding genome regions of two bovine enterovirus strains.

The sequence of cDNA clones representing the 5' non-coding regions (NCR) and capsid regions of two bovine enteroviruses (strains PS-87 and RM-2; serotype two viruses) have been determined and compared with that obtained from a serotype one strain (VG-5-27). All three strains showed a longer 5' NCR compared to human enteroviruses and rhinoviruses due in part to a hundred residue insertion approximately at a hundred residues in from the 5' end. However, another domain occurring at nucleotide 187-222 in poliovirus is absent in each bovine enterovirus. Comparisons of the predicted structural protein amino acid sequences indicate that PS-87 shares most sequence identity with RM-2 and then with VG-5-27 in that order. The VP1 protein of PS-87 and RM-2 are shorter than the equivalent VP1 of VG-5-27 due in part to a truncation at their C-terminii. VP3 is only slightly smaller than VP2 in each virus.

Amino Acid Sequence↗
PubMed1991

The capsid protein-encoding sequence of foot-and-mouth disease virus O2Brescia.

Nucleotide sequences encoding the four capsid proteins of foot-and-mouth disease virus subtype O2Brescia/1947 have been determined. These and the deduced amino acid sequences were compared with those of a subtype O1 virus strain. The nucleotide sequences differed at 259 positions, causing only 35 amino acid changes. VP4 and VP2 differed by 2.4 and 1.8%, whereas VP1, known as major viral antigen, and VP3 differed by 8% and 5.5%, respectively. The differences occur mainly in protein domains not involved in the formation of alpha-helices and beta-sheets, suggesting that the surfaces of both viruses are more variable than their scaffolds. The O2Brescia sequence has been submitted to the GenBank data base and has the accession number M 55287.

Amino Acid Sequence↗
PubMed1994

Two nucleolar targeting signals present in the N-terminal part of Semliki Forest virus capsid protein.

Here we show that the capsid (C) protein of Semliki Forest virus (SFV) contains two nucleolar targeting signals (NOS) responsible for the karyophilic properties of this protein. When conjugated to the non-karyophilic carrier protein bovine serum albumin (BSA), the two synthetic nuclear localization sequences (NLS) of the C protein transferred with equal efficiency the carrier protein into the nucleolus of both higher and lower eukaryotic target cells.

Amino Acid Sequence↗
PubMed1989

Cloning of the potato virus Y genes encoding the capsid protein CP and the nuclear inclusion protein NIb.

DNA was synthesized complementary to the RNA genome of potato virus Y (PVY; strain GO 16) and cloned into lambda vectors. The size of PVY-specific Eco RI-restricted cDNA ranged from 0.3 to approximately 22kb. Two of the cDNA clones each of which contained some 4kb of cDNA sequence starting from the 3'-polyadenylated terminus were characterized by sequence analysis. Presence of a single open reading frame suggests that PVY-specific proteins are synthesized as a polyprotein precursor. As with other sequenced potyvirus RNAs the gene for the PVY capsid protein CP is located next to the 3'-untranslated region followed by the genes for the putative RNA polymerase (nuclear inclusion protein NIb) and the virus-specific protease (nuclear inclusion protein NIa). The 3'-trailing sequence of the PVY strains cloned is highly homologous to the corresponding region of pepper mottle virus (PeMV) and suggests that PeMV is not a distinct member of the potyvirus group, but another strain of PVY.

Amino Acid Sequence↗