Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Insect 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 1,441 records · Page 80Linked to original sources
PubMed1986

DNA methyltransferase induced by PBCV-1 virus infection of a Chlorella-like green alga.

A DNA methyltransferase was isolated from a eucaryotic, Chlorella-like green alga infected with the virus PBCV-1. The enzyme recognized the sequence GATC and methylated deoxyadenosine solely in GATC sequences. Host DNA, which contains GATC sequences, but not PBCV-1 DNA, which contains GmATC sequences, was a good substrate for the enzyme in vitro. The DNA methyltransferase activity was first detected about 1 h after viral infection; PBCV-1 DNA synthesis and host DNA degradation also began at about this time. The appearance of the DNA methyltransferase activity required de novo protein synthesis, and the enzyme was probably virus encoded. Methylation of DNAs with the PBCV-1-induced methyltransferase conferred resistance of the DNAs to a PBCV-1-induced restriction endonuclease enzyme described previously (Y. Xia, D. E. Burbank, L. Uher, D. Rabussay, and J. L. Van Etten, Mol. Cell. Biol. 6:1430-1439). We propose that the PBCV-1-induced methyltransferase protects viral DNA from the PBCV-1-induced restriction endonuclease and is part of a virus-induced restriction and modification system in PBCV-1-infected Chlorella cells.

Cell Transformation, Viral↗
PubMed1993

Identification of an Amsacta spheroidin-like protein within the occlusion bodies of Choristoneura entomopoxviruses.

Like baculoviruses, a characteristic feature of entomopoxviruses is the amalgamation of virions within environmentally stable occlusion bodies. It is this occluded form of the virus that is primarily responsible for dissemination to other insects. While the major protein (polyhedrin) of baculovirus occlusions is quite similar between viruses, it has been reported that the major occlusion body protein (spheroidin) of two group B entomopoxviruses, Amsacta moorei (AmEPV) and Choristoneura biennis (CbEPV) is quite different both in terms of amino acid sequence and coding capacity of the corresponding spheroidin genes (115 and 47 kDa for AmEPV and CbEPV, respectively). We report the discovery of a AmEPV spheroidin gene homolog in both CbEPV and a second Choristoneura virus, Choristoneura fumiferana (CfEPV). Antibodies directed against the AmEPV 115-kDa spheroidin reacted with the major protein of approximately 115 kDa found within the occlusion body preparation from both Choristoneura viruses. Direct protein microsequencing of small portions of the 115-kDa protein from CbEPV has resulted in peptide sequences identical to those of corresponding regions of the AmEPV spheroidin gene. We suggest that it is this Choristoneura gene which encodes spheroidin. All attempts, however, to find a homolog of the previously reported CbEPV spheroidin gene within AmEPV have been unsuccessful. We also show this newly identified Choristoneura homolog of the AmEPV spheroidin gene as well as the AmEPV spheroidin gene itself are both located at the 3' end of an NPH I gene and are highly homologous in all three viruses, indicating that this region of the genome in the three viruses is co-linear. These results and others suggest that while the insect viruses lack the traditional central core of conserved genes observed for the vertebrate poxviruses, the insect poxviruses may have also evolved an alternative central core of conserved genes, unique to the invertebrate poxviruses.

Amino Acid Sequence↗
PubMed1988

Synthesis of functional human immunodeficiency virus tat protein in baculovirus as determined by a cell-cell fusion assay.

The human immunodeficiency virus tat protein is a strong trans-activator of the expression of mRNAs originating from the viral long terminal repeat. We have expressed the first 72 amino acids (coding exon 1) of this protein in eucaryotic Spodoptera frugiperda SF9 cells by using a baculovirus vector, Autographa californica nuclear polyhedrosis virus. We show that the baculovirus vector stably produced the 72-amino-acid form of the tat protein but was unable to stably synthesize a larger 101-amino-acid full-length version of the same polypeptide. The 72-amino-acid tat protein, when introduced into mammalian fibroblasts by using a cell-cell fusion technique, functionally trans-activated the expression of the human immunodeficiency virus long terminal repeat.

Amino Acid Sequence↗
PubMed1992

Expression of Epstein-Barr virus membrane antigen gp350/220 in E. coli and in insect cells.

The Epstein-Barr virus open reading frame BLLF1 encodes the major envelope glycoproteins gp350 and gp220. Fragments of the gp350/220 gene were expressed in Escherichia coli in order to define regions of the polypeptide chain reacting with human sera. The C-terminal half of the protein was sufficient for recognition by all VCA-positive sera tested. A membrane anchor truncated version of gp350/220 was expressed in insect cells using the baculovirus system. Proteins of different sizes were specifically detected in the cells while a glycosylated 220-kDa protein was secreted. The insect cells were tested for their suitability as tools for performing monospecific immunofluorescence.

Animals↗
PubMed2003

Entry is a rate-limiting step for viral infection in a Drosophila melanogaster model of pathogenesis.

The identification of host factors that control susceptibility to infection has been hampered by a lack of amenable genetic systems. We established an in vivo model to determine the host factors that control pathogenesis and identified viral entry as a rate-limiting step for infection. We infected Drosophila melanogaster cells and adults with drosophila C virus and found that the clathrin-mediated endocytotic pathway is essential for both infection and pathogenesis. Heterozygosity for mutations in genes involved in endocytosis is sufficient to protect flies from pathogenicity, indicating the exquisite sensitivity and dependency of the virus on this pathway. Thus, this virus model provides a sensitive and efficient approach for identifying components required for pathogenesis.

Animals↗
PubMed1971

Characterization of the genome of cytoplasmic polyhedrosis virus.

It is possible to oxidize in situ the 3'-terminals of the double-stranded ribonucleic acid (RNA) contained in structurally intact cytoplasmic polyhedrosis virus. The number of 3'-terminals subsequently found by reduction with tritiated sodium borohydride was equivalent to the number observed in RNA first isolated from the virus and then oxidized and reduced. The viral RNA appears to occur in 10 distinct polynucleotide segments present in equimolar amounts.

Borohydrides↗
PubMed1978

Immunochemical characterization of Lymantri dispar NPV hemagglutinin: protein-carbohydrate interaction.

The agglutination of chicken erythrocytes by Lymantria dispar nuclear polyhedrosis virus polyhedrin has been shown to provide specific virus identification. Selected mono- and oligosaccharides, present in blood group substances, were assayed by the Land-steiner hapten inhibition technique for specific inhibition of polyhedrin hemagglutination. N-acetylgalactosamine and N-acetylglucosamine inhibit to the greatest extent; galactosamine, glucosamine and fucose to a lesser extent. The hapten inhibition data suggest that a monosaccharide possessing an equatorial 2-acetamido group interacts most avidly with the polyhedrin-combining site. Bergold demonstrated that the polyhedrin dissociates into six subunits at a pH greater than 10.0. Diafiltration equilibrium and Scatchard analysis indicate that N-acetylgalactosamine binds most avidly to the polyhedrin (Kd = 1.7 X 10(-6)) which contains six available sites, suggesting that one hemagglutination site resides on each subunit. Since virions derived in vivo and polyhedrin are serologically cross-reactive, this protein-carbohydrate interaction may play a role in host infectivity by providing a receptor site for virus attachment to target cells.

Acetylgalactosamine↗
PubMed1996

Synthesis of soluble rubella virus spike proteins in two lepidopteran insect cell lines: large scale production of the E1 protein.

The two envelope glycoproteins of rubella virus (RV), E1 of 58 kDa and E2 of 42-47 kDa, were individually expressed in lepidopteran Spodoptera frugiperda as well as in Trichoplusia ni insect cells using baculovirus vectors. The authentic signal sequences of E1 and E2 were replaced with the honeybee melittin signal sequence, allowing efficient entrance into the secretory pathway of the insect cell. In addition, the hydrophobic transmembrane anchors at the carboxyl termini of E1 and E2 proteins were removed to enable secretion rather than maintenance in the cellular membranes. Synthesis of the recombinant proteins in the absence and presence of tunicamycin revealed that both E1 and E2 were glycosylated with apparent molecular weights of 52 kDa and 37 kDa, respectively. Recombinant E2 appeared to be partially secreted, whereas E1 was essentially found inside the infected insect cell. The E1 protein was produced in large scale using a 10-1 bioreactor and serum-free medium (SFM). Purification of the recombinant protein product was performed from cytoplasmic extracts by ammonium sulphate precipitation followed by Concanavalin A affinity chromatography. This type of purified recombinant viral glycoproteins may be useful not only in diagnostic medicine or for immunization, but should enable studies designed to solve the structure of the virus particle.

Animals↗
PubMed2005

[Expression of tick-borne encephalitis virus prM-E protein in insect cells and studies on its antigenicity].

BACKGROUND: To express the prM-E protein in Sf9 cells, and lay a basis for further study on the function of the viral proteins and development of specific diagnostic reagents. METHODS: The recombinant prM-E protein of tick-borne encephalitis virus was expressed in insect cell Sf9 by RT-PCR amplification of prM-E gene, construction of donor plasmid of Bac-to-Bac baculovirus expression system, homologous recombination of donor plasmid with bacmid DNA at the site of Tn7 and transfection of insect cell Sf9. RESULTS: Recombinant subviral particles, about 30 nm in diameter, consisting of prM-E were observed by electron microscope in the supernatant of infected cells, which indicated that infected cells released virus-like particles (VLPs) into the culture medium. The results of Western-blot and the indirect immunofluorescence assay (IFA) showed that the recombinant proteins retained antigenic and conformational structures similar to those of native virus proteins. Using the recombinant prM-E as antigens to detect samples of patient sera by ELISA and IFA, all of 16 sera from patients with tick-borne encephalitis were positive and all of 6 sera from other patients were negative. CONCLUSION: The prM-E protein expressed in insect cells retains good antigenicity.

Animals↗
PubMed1984

Identification and localization of reiterated sequences in the Choristoneura fumiferana MNPV genome.

The genome of Choristoneura fumiferana nuclear polyhedrosis virus (CfMNPV) contained reiterated sequences interdispersed in four locations. These regions, termed RS, were found in EcoRI fragments A, F, E and B. The sequences were identified by hybridization of the fragment EcoRI-A to a Southern blot of EcoRI-digested viral DNA. Further confirmation and more precise localization of the RS sequences was obtained by hybridization of nick-translated 32P-labeled EcoRI-E fragment to Southern blots of viral DNA digested with EcoRI, BamHI, XbaI and Bg/II. Hybridization of 32P-labeled EcoRI-E to HindIII blots of viral DNA revealed the presence of a 'ladder' consisting of eight fragments. The three fragments of the ladder with the lowest sizes represented the HindIII fragments, O, PQ and R. The other five fragments were submolar in amount, in that they could not be seen in ethidium bromide-stained gels and probably represented minor virus variants that arose after passage of virus in larvae. Each variant was distinguished from the others by an additional insertion of 210 bp into the EcoRI-B fragment of the genome.

Chromosome Mapping↗
PubMed1990

Implication of mitochondria in the replication of Nodamura virus in larvae of the Lepidoptera, Galleria mellonella (L.) and in suckling mice.

The replication of Nodamura virus, type species of the family Nodaviridae, takes place principally into the interfibrillar spaces of the sarcoplasm in close association with mitochondria in the infected muscles of both G. mellonella and suckling mice. The most striking event in infection of G. mellonella muscle cells was the aggregation and shape modification of numerous mitochondria (elongation, interdigitation, and vesiculation) at an early stage of infection. These clusters of mitochondria were cemented by a thick electron-dense material at the periphery of which viral particles undergo maturation process. In a later stage, degenerated and dilated mitochondria showed a clear assembling of virus particles on their outer membrane and occasionally on some inner membranes. These facts and the localization of RNA by RNase-gold technique in the assembling sites of viruses around and inside the mitochondria allowed us to postulate a role for the mitochondria as supports and/or energy suppliers for viral RNA synthesis and translation.

Animals↗
PubMed1989

Nucleotide sequence and expression of the small (S) RNA segment of Maguari bunyavirus.

The small (S) RNA segment of the Maguari bunyavirus genome has been cloned as cDNA and its nucleotide sequence determined. The nucleocapsid protein, N, (Mr 26K) and a nonstructural protein, NSs, (Mr 11K), are encoded in overlapping reading frames, similar to other bunyavirus S RNA segments. In addition, a third AUG-initiated open reading frame encoding a 9.3K protein was observed. All three polypeptides were translated in cell free systems programmed with RNA transcribed in vitro from the cDNA subcloned downstream of a bacteriophage T7 promoter. The effects on expression of subcloning parts of the cDNA and by site-specific mutagenesis are discussed in relation to the scanning model of initiation of translation. A recombinant baculovirus has been constructed to express the Maguari virus S segment gene products. The N protein was efficiently expressed in infected cells, and a significant amount was in a soluble form. We could not detect the synthesis of NSs nor the 9.3K protein, and the reasons for this are discussed. The 9.3K protein has not been found in Maguari virus-infected cells and so the question of its functional significance remains open.

Amino Acid Sequence↗
PubMed2006

Detection and characterisation of three novel species of reovirus (Reoviridae), isolated from geographically separate populations of the winter moth Operophtera brumata (Lepidoptera: Geometridae) on Orkney.

Geographically separate populations of winter moth (Operophtera brumata L.) were sampled in heather habitats on the Orkney Isles in order to investigate the prevalence of virus pathogens. Reoviruses were isolated in 11 of the 13 winter moth populations sampled, with 3 novel species being detected. Two species of Cypoviridae (CPV) were isolated, Operophtera brumata CPV18 and O. brumata CPV19, with one host population suffering 46% infection prevalence of OpbuCPV19. A third virus, O. brumata Reovirus (OpbuRV), was isolated from both winter moth and a hymenopteran parasitoid wasp, Phobocampe tempestiva, which is abundant in these populations. This was identified as a non-occluded reovirus, which was clearly able to infect and persist in both the lepidopteran and the hymenopteran host. The genomes of the three viruses were characterised using gel electrophoresis and the virus structure was investigated using transmission electron microscopy. The relationship of these viruses with a baculovirus that also infects winter moth, OpbuNPV, was investigated, as well as the association of OpbuRV with P. tempestiva. The detection of such viruses is discussed with reference to studies of similar viruses in other lepidopteran and hymenopteran host systems.

Animals↗
PubMed1990

Comparative study of virion structure, protein composition and genomic DNA of three ascovirus isolates.

The virions of three ascoviruses isolated from the noctuids Heliothis zea, Spodoptera frugiperda and Trichoplusia ni were compared with respect to their size and structure, protein composition and the size and relatedness of their DNAs. The virions of the isolates from H. zea (HAV) and T. ni (TAV) were allantoid in shape (400 x 130 nm), enveloped and contained an inner particle which appeared to have an internal lipid bilayer surrounding the DNA core. The virions of the S. frugiperda isolate (SAV) were similar in structure and size, but were bacilliform in shape, and after formation, were often occluded in vesiculate occlusion bodies. In preparations of purified virions of each isolate, at least 12 polypeptides were detected that ranged in size from 10K to 200K and contained a major species of about 50K. The genome of SAV was about 140 kbp in size, whereas those of TAV and HAV were approximately 180 kbp. Analysis of DNA fragment patterns of the three isolates generated with BamHI, HindIII or XhoI, as well as DNA-DNA dot blot and Southern blot hybridization studies, demonstrated that HAV and TAV were closely related but not identical. The DNA from SAV, however, did not hybridize with the DNA from either of the other isolates. Thus the ascovirus isolates from T. ni and H. zea are considered variants of the same virus, whereas the isolate from S. frugiperda is a separate member of the ascovirus group.

Animals↗
PubMed1975

Development of Amsacta moorei entomopoxvirus in ovarian and hemocyte cultures from Estigmene acrea larvae.

Primary ovarian and hemocyte tissue cultures prepared from Estigmene acrea larvae were infected with Amsacta moorei entomopoxvirus. Infection of cultures was achieved with either purified virus or virus-containing culture medium from infected cultures. Virus replication and formation of virus-containing inclusions (VCI) were similar to that normally observed in vivo except that fewer virions appeared to be occluded in VCI.

Blood Cells↗
PubMed1990

Characterisation of an avian influenza virus nucleoprotein expressed in E. coli and in insect cells.

The nucleoprotein (NP) gene from influenza virus A/Shearwater/Australia/72 has been expressed intracellularly in both E. coli and insect cells. E. coli-derived NP was identified by Western blot analysis as a 56 kDa protein which co-migrates with virion-derived NP. This protein was purified by immunoaffinity chromatography and a nitrocellulose binding assay showed that NP formed complexes with positive- and negative-sense influenza neuraminidase RNA transcribed in vitro. ELISA and Western blot analysis revealed that recombinant NP of 56 kDa was produced in high yields in insect cells using a baculovirus vector. Immunofluorescence microscopy revealed that NP was localised to the nucleus of infected insect cells.

Animals↗
PubMed1988

In vivo isolation of baculovirus genotypes.

Restriction endonuclease profiles of a wild-type granulosis virus from Artogeia rapae (ArGV3) and a nuclear polyhedrosis virus from Lymantria dispar (LdMNPV) indicated that the preparations were genotypically heterogeneous. Eight constituent genotypes were isolated from ArGV3 by low mortality dose infections of late instar A. rapae and analysis of progeny viral DNA recovered from individual cadavers. Three distinct genotypes were isolated from LdMNPV by the same approach, using L. dispar larvae. These results show that larval mortality can occur as a consequence of productive infection by a single virus particle. Comparative physical mapping of the eight ArGV3 genotypes suggested that their diversity may be partly attributable to recombination during natural coinfection.

DNA Restriction Enzymes↗