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 487 records · Page 27Linked to original sources
PubMed1999

Immunogenicity of a recombinant infectious hematopoietic necrosis virus glycoprotein produced in insect cells.

A recombinant infectious hematopoietic necrosis virus (IHNV) glycoprotein (G protein), produced in Spodoptera frugiperda (Sf9) cells following infection with a baculovirus vector containing the full-length (1.6 kb) glycoprotein gene, provided very limited protection in rainbow trout Oncorhynchus mykiss challenged with IHNV. Fish were injected intraperitoneally (i.p.) with Sf9 cells grown at 20 degrees C (RecGlow) or 27 degrees C (RecGhigh) expressing the glycoprotein gene. Various antigen (Ag) preparations were administered to adult rainbow trout or rainbow trout fry. Sera collected from adult fish were evaluated for IHNV neutralization activity by a complement-dependent neutralization assay. Anti-IHNV neutralizing activity was observed in sera, but the percent of fish responding was significantly lower (p < 0.05) in comparison to fish immunized with a low virulence strain of IHNV (LV-IHNV). A small number of fish immunized with RecGlow or RecGhigh possessed IHNV G protein specific antibodies (Abs) in their serum. Cumulative mortality (CM) of rainbow trout fry (mean weight, 1 g) vaccinated by i.p. injection of freeze/thawed Sf9 cells producing RecGlow was 18% in initial trials following IHNV challenge. This level of protection was significant (p < 0.05) but was not long lasting, and neutralizing Abs were not detected in pooled serum samples. When trout fry (mean weight, 0.6 g) were vaccinated with supernatant collected from sonicated Sf9 cells, Sf9 cells producing RecGlow, or Sf9 cells producing RecGhigh, CM averaged 46%. Protection was enhanced over negative controls, but not the positive controls (2% CM), suggesting that in the first trial soluble cellular proteins may have provided some level of non-specific protection, regardless of recombinant protein expression. Although some immunity was elicited in fish, and RecGlow provided short-term protection from IHNV, Ab-mediated protection could not be demonstrated. The results suggest that recombinant G proteins produced in insect cells lack the immunogenicity associated with vaccination of fish with an attenuated strain of IHNV.

Animals↗
PubMed1998

[Expression of secreted ligand domain of vaccinia growth factor encoded by vaccinia virus strain tian tan in E. coli and insect cells].

Vaccinia virus growth factor (VGF) is encoded by an early gene of vaccinia virus strain TianTan located near the border between the terminal inverted repeats and the internal region of the viral genome as one copy. Its relationship to members of epidermal growth factor superfamily was discovered when computer searches of protein sequences revealed that VGF has strong sequence homology with these growth factors. To further get insight into the biological activity of VGF, we cloned and expressed the secreted ligand domain of VGF (VGFsl) encoded by vaccinia virus strain TianTan in E. coli and insect cells. The results of biological activity test indicated that expressed products is capable of binding to the EGF receptor, and stimulating EGF receptor tyrosin autophosphorylation to a level greater than that of EGF.

Animals↗
PubMed1997

Biochemical characterization of a smaller form of recombinant Norwalk virus capsids assembled in insect cells.

The expression of the single capsid protein of Norwalk virus (NV) in Spodoptera frugiperda (Sf9) insect cells infected with recombinant baculovirus results in the assembly of virus-like particles (VLPs) of two sizes, the predominant 38-nm, or virion-size VLPs, and smaller, 23-nm VLPs. Here we describe the purification and biochemical characterization of the 23-nm VLPs. The 23-nm VLPs were purified to 95% homogeneity from the medium of Sf9 cultures by isopycnic CsCl gradient centrifugation followed by rate-zonal centrifugation in sucrose gradients. The compositions of the purified 23- and 38-nm VLPs were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and protein immunoblots. VLPs of both sizes showed a doublet at 58 kDa, the size of the full-length capsid protein. Upon alkaline treatment, the 23-nm VLPs underwent dissociation into soluble intermediates that were able to reassemble into 23- and 38-nm VLPs upon dialysis, suggesting that the assembly of both types of structures has a common pathway. Antigenic and biochemical properties of the 38- and 23-nm VLPs were examined and found to be conserved. Immunoprecipitation assays using polyclonal and monoclonal antibodies indicated that immunodominant epitopes on the capsid protein as well as conformational epitopes are conserved in the two types of particles. The trypsin cleavage site at residue 227 was protected in the assembled particles of both sizes but exposed after alkaline dissociation. These results, and the conservation of the binding activity of both forms of recombinant NV VLPs to cultured cells (L. J. White, J. M. Ball, M. E. Hardy, T. N. Tanaka, N. Kitamoto, and M. K. Estes, J. Virol. 70:6589-6597, 1996), suggest that the tertiary folding of the capsid protein responsible for these properties is conserved in the two structures. We hypothesize that the 23-nm VLPs are formed when 60 units of the NV capsid protein assembles into a structure with T=1 symmetry.

Animals↗
PubMed1986

[Infection of insect cell lines by the HIV virus, an agent of AIDS, and a demonstration of insects of African origin infected by this virus].

The etiological agent of AIDS known as HIV has been shown to bind on different insect cell lines including Drosophila, Mosquito, Ceratitis; and his DNA to be integrated in the cellular genome, but no expression of the viral genome was detected in those cells. None of the human lymphocytes markers is expressed at the surface of the insect cells. HIV proviral DNA has been also found in various insects from Central Africa (Zaïre and Central Africa Republic) but not similar insects from the Paris area. These data suggest that insects could be a reservoir or a vector for the AIDS virus.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Genetic and phenotypic characterization of the newly described insect flavivirus, Kamiti River virus.

We have described in the accompanying paper by Sang, et al., ([57], Arch Virol 2003, in press) the isolation and identification of a new flavivirus, Kamiti River virus (KRV), from Ae. macintoshi mosquitoes that were collected as larvae and pupae from flooded dambos in Central Province, Kenya. Among known flaviviruses, KRV was shown to be most similar to, but genetically and phenotypically distinct from, Cell fusing agent virus (CFAV). KRV was provisionally identified as an insect-only flavivirus that fails to replicate in vertebrate cells or in mice. We report here the further characterization of KRV. Growth in cell culture was compared to that of CFAV; although growth kinetics were similar, KRV did not cause the cell fusion that is characteristic of CFAV infection. The KRV genome was found to be 11,375 nucleotides in length, containing a single open reading frame encoding 10 viral proteins. Likely polyprotein cleavage sites were identified, which were most similar to those of CFAV and were comparable to those of other flaviviruses. Sequence identity with other flaviviruses was low; maximum identity was with CFAV. Possible terminal secondary structures for the 5' and 3' non-coding regions (NCR) were similar to those predicted for other flaviviruses. Whereas CFAV was isolated from insect cells in the laboratory, the isolation of KRV demonstrates the presence of an insect-only flavivirus in nature and raises questions regarding potential interactions between this virus and other mosquito-borne viruses in competent vector populations. Additionally, this virus will be an important tool in future studies to determine markers associated with flavivirus host specificity.

Aedes↗
PubMed1992

Equilibrium and kinetic analysis of Autographa californica nuclear polyhedrosis virus attachment to different insect cell lines.

The kinetic and equilibrium attachment of Autographa californica nuclear polyhedrosis virus (AcMNPV) to seven insect cell lines was evaluated. Kinetic experiments revealed differences of up to 10-fold in the infection rates among cell lines. Equilibrium binding also varied between cell lines and was saturable. The Tn 5B1-4 and Tn F cell lines had the highest virus binding affinities and infection rates and exhibited diffusion-limited attachment. The rate of infection appears to be limited by the rate of attachment. For the Tn 5B1-4 cells the physical to infective particle ratio for AcMNPV was 5.3. From the Scatchard analyses, the cell lines Tn 5B1-4 and Tn F displayed affinities of 2.35 x 10(10) M-1 and 1.60 x 10(10) M-1, respectively, with 6000 and 13,700 binding sites per cell. The insect cell line Hz 1075, which is not susceptible to AcMNPV infection, displayed a much lower, but saturable, binding of AcMNPV with 900 sites/cell and an affinity of 1.1 x 10(10) M-1. Unlabelled AcMNPV, but not Lymantria dispar MNPV could compete with labelled AcMNPV for binding sites. There were 93 to 96% reductions in virus cell binding following pretreatments of cells with three proteases, suggesting the involvement of a cellular protein component in virus binding. Tunicamycin, an inhibitor of N-linked glycosylation and expression of some membrane proteins on the cell surface, reduced virus binding in a dose-dependent manner suggesting a role for glycoprotein(s) in binding. However there was no evidence for the direct involvement of oligosaccharides in attachment. Metabolic inhibitors of oligosaccharide trimming and competition binding assays using simple sugars caused no measurable reductions in virus binding. These findings suggest that AcMNPV attachment to insect cells is receptor-mediated via a glycoprotein component(s); the direct involvement of oligosaccharide moieties in binding is unlikely.

Animals↗
PubMed1993

Expression of the human foamy virus bel-1 transactivator in insect cells.

The human foamy virus (HFV) bel-1 transactivator protein was expressed in insect cells by a recombinant baculovirus. For the generation of the recombinant baculovirus, Acbel-1, the bel-1 gene of an HFV mutant was used, that bears truncations in the bel-1 overlapping bel-2 open reading frame. Acbel-1 infected Sf9 cells produced high amounts of recombinant protein of the same electrophoretic mobility (36 kD) as bel-1 expressed in mammalian cells. The baculovirus expressed bel-1 protein was readily identified by a polyclonal rabbit serum directed against bel-1 in immunoblot assay. As in mammalian cells, bel-1 was predominantly localized to the nucleus of Acbel-1 infected insect cells. The baculovirus expressed bel-1 protein will be of use to determine the action of this novel viral transactivator more precisely.

Animals↗
PubMed1989

Assembly and release of HIV-1 precursor Pr55gag virus-like particles from recombinant baculovirus-infected insect cells.

The unprocessed Gag precursor from HIV-1, when expressed in recombinant baculovirus-infected insect cells, is targeted to the plasma membrane and assembles in 100-120 nm particles budding from the cell surface. This process mimics HIV immature particle formation and is dependent on myristoylation of the N-terminal glycine, as deletion of the latter results in particle accumulation in the cytoplasm and, interestingly, in the nucleus, pointing to a potential role of this non-fatty-acid-acylated species in the viral life cycle. Inclusion of the pol gene in the construct results in efficient processing of Pr55gag and a pronounced decrease in particle formation. Deletion of the C terminus (p16) of the Gag precursor, including the finger domains, abolishes particle assembly, but membrane targeting and evagination still occur. Heterologous expression in insect cells may prove very useful for the study of the molecular events leading to retroviral particle morphogenesis.

Animals↗
PubMed1967

Electron microscopy of the formation of wound tumor virus in abdominally inoculated insect vectors.

Fifth-instar nymphs of Agallia constricta leafhoppers were injected abdominally with extracts from root tumors confining wound tumor virus (WTV). The insects were sacrificed at predetermined intervals, their internal organs dissected, fixed, embedded, sectioned, stained, and examined in a Siemens Elmiskop I. Sequential stages in virus development were reconstructed from consecutive samples of fatbody tissues. Changes resulting from the infection were: (i) a viroplasm, i.e., an accumulation of electron-dense aggregates; (ii) the appearance at the periphery of the viroplasm of a few fully formed virus particles recognized as virions; (iii) the formation of increasing numbers of individual virions, not only at the periphery but also in the viroplasm; (iv) the engulfing of virions within multimembranous structures; and (v) the formation of virus microcrystals either at the sites of former viroplasms, or at some distance. These morphological findings indicate that, following abdominal inoculation of WTV, the plant-pathogenic virus develops within the cytoplasmic matrix proper of insect vector cells. In addition to the fatbody tissues, WTV was detected in the epidermis, muscles, and trachea of abdominally inoculated insects, demonstrating the systemic invasion of the mechanically infected arthropod host. No virus was found in the gut tissues.

Journal Article↗
PubMed1999

[Cloning and expression of bluetongue virus VP3 protein in insect cells].

OBJECTIVE: To elucidate the biological activities of VP3 protein of bluetongue virus (BTV) expressed in insect cells and to assemble, in future, the BTV core-like particles. METHODS: First, full length of BTV13 L3 cDNA was constructed from 2 sequenced clones. The silver staining of the splicing region proved that the construction was correct. Then, a recombinant baculovirus expression vector pFB1BL3 was constructed to express the L3 gene in insect cells. RESULTS: BTV13 VP3 could be highly expressed in Sf-9 cells, the production could occupy up to 10%-15% of the total cell protein. Core-like particles could be observed after co-expression of the VP3 and VP7 in insect cells. CONCLUSION: VP3 of BTV expressed in insect cells possesses biological activity and can be used to assemble BTV core-like particles.

Animals↗
PubMed1999

Immunoblot analysis of natural and vaccine-induced IgG responses to rubella virus proteins expressed in insect cells.

BACKGROUND: The three structural proteins of rubella virus (RV), the capsid protein C and the envelope glycoproteins E1 and E2, were produced individually in soluble form in Sf9 insect cells using the baculovirus system. All proteins were equipped with a polyhistidine tag at their C-terminal ends to enable gentle purification by metal ion affinity chromatography. In addition, the E1 and E2 proteins were engineered to display the FLAG epitope tag at their N-terminal ends. STUDY DESIGN: The diagnostic potential of the recombinant purified proteins was evaluated by immunoblot and enzyme immuno assays (EIA) using a total of 57 well-characterised serum samples obtained at various time points after natural RV infection, congenital rubella syndrome (CRS), MMR vaccination or from controls with past RV immunity. In addition, acute and convalescent phase serum pools from a total of 20 patients were evaluated. Authentic RV proteins were used as a reference. RESULTS: The recombinant E1 and C proteins were predominant in eliciting the immune response in both postnatal and vaccinal RV infections, being much weaker in the vaccinal ones. The IgG response to the recombinant C protein was very strong after the first month post infection and decreased with time. The immune response against the recombinant E2 protein, however, was generally poor, but notably stronger after congenital infection. Together, the results showed that the individual recombinant protein antigens could be suitable for diagnosis of RV infection and for study of the immune response to rubella vaccination.

Adolescent↗
PubMed2002

The palm subdomain-based active site is internally permuted in viral RNA-dependent RNA polymerases of an ancient lineage.

Template-dependent polynucleotide synthesis is catalyzed by enzymes whose core component includes a ubiquitous alphabeta palm subdomain comprising A, B and C sequence motifs crucial for catalysis. Due to its unique, universal conservation in all RNA viruses, the palm subdomain of RNA-dependent RNA polymerases (RdRps) is widely used for evolutionary and taxonomic inferences. We report here the results of elaborated computer-assisted analysis of newly sequenced replicases from Thosea asigna virus (TaV) and the closely related Euprosterna elaeasa virus (EeV), insect-specific ssRNA+ viruses, which revise a capsid-based classification of these viruses with tetraviruses, an Alphavirus-like family. The replicases of TaV and EeV do not have characteristic methyltransferase and helicase domains, and include a putative RdRp with a unique C-A-B motif arrangement in the palm subdomain that is also found in two dsRNA birnaviruses. This circular motif rearrangement is a result of migration of approximately 22 amino acid (aa) residues encompassing motif C between two internal positions, separated by approximately 110 aa, in a conserved region of approximately 550 aa. Protein modeling shows that the canonical palm subdomain architecture of poliovirus (ssRNA+) RdRp could accommodate the identified sequence permutation through changes in backbone connectivity of the major structural elements in three loop regions underlying the active site. This permutation transforms the ferredoxin-like beta1alphaAbeta2beta3alphaBbeta4 fold of the palm subdomain into the beta2beta3beta1alphaAalphaBbeta4 structure and brings beta-strands carrying two principal catalytic Asp residues into sequential proximity such that unique structural properties and, ultimately, unique functionality of the permuted RdRps may result. The permuted enzymes show unprecedented interclass sequence conservation between RdRps of true ssRNA+ and dsRNA viruses and form a minor, deeply separated cluster in the RdRp tree, implying that other, as yet unidentified, viruses may employ this type of RdRp. The structural diversification of the palm subdomain might be a major event in the evolution of template-dependent polynucleotide polymerases in the RNA-protein world.

Amino Acid Motifs↗
PubMed2000

Insect transmission of plant viruses: a constraint on virus variability.

Genetic diversity in viruses is shaped by high rates of recombination and is constrained by host defenses and the requirements of transmission. Recent studies of insect-transmitted plant viruses demonstrate highly conserved molecular motifs in viral genomes that regulate the specificity of insect transmission. In contrast, advances in our understanding of host plant response to virus infection reveal some generalized patterns of host defense to a diversity of viruses.

Animals↗
PubMed2002

Comparative analysis of the genome and host range characteristics of two insect iridoviruses: Chilo iridescent virus and a cricket iridovirus isolate.

The iridovirus isolate termed cricket iridovirus (CrIV) was isolated in 1996 from Gryllus campestris L. and Acheta domesticus L. (both Orthoptera, Gryllidae). CrIV DNA shows distinct DNA restriction patterns different from those known for Insect iridescent virus type 6 (IIV-6). This observation led to the assumption that CrIV might be a new species within the family Iridoviridae. CrIV can be transmitted perorally to orthopteran species, resulting in specific, fatal diseases. These species include Gryllus bimaculatus L. and the African migratory locust Locusta migratoria migratorioides (Orthoptera, Acrididae). Analysis of genomic and host range properties of this isolate was carried out in comparison to those known for IIV-6. Host range studies of CrIV and IIV-6 revealed no differences in the peroral susceptibility in all insect species and developmental stages tested to date. Different gene loci of the IIV-6 genome were analyzed, including the major capsid protein (274L), thymidylate synthase (225R), an exonuclease (012L), DNA polymerase (037L), ATPase (075L), DNA ligase (205R) and the open reading frame 339L, which is homologous to the immediate-early protein ICP-46 of frog virus 3. The average identity of the selected viral genes and their gene products was found to be 95.98 and 95.18% at the nucleotide and amino acid level, respectively. These data led to the conclusion that CrIV and IIV-6 are not different species within the Iridoviridae family and that CrIV must be considered to be a variant and/or a novel strain of IIV-6.

Amino Acid Sequence↗
PubMed2006

Scalable generation of high-titer recombinant adeno-associated virus type 5 in insect cells.

We established a method for production of recombinant adeno-associated virus type 5 (rAAV5) in insect cells by use of baculovirus expression vectors. One baculovirus harbors a transgene between the inverted terminal repeat sequences of type 5, and the second expresses Rep78 and Rep52. Interestingly, the replacement of type 5 Rep52 with type 1 Rep52 generated four times more rAAV5 particles. We replaced the N-terminal portion of type 5 VP1 with the equivalent portion of type 2 to generate infectious AAV5 particles. The rAAV5 with the modified VP1 required alpha2-3 sialic acid for transduction, as revealed by a competition experiment with an analog of alpha2-3 sialic acid. rAAV5-GFP/Neo with a 4.4-kb vector genome produced in HEK293 cells or Sf9 cells transduced COS cells with similar efficiencies. Surprisingly, Sf9-produced humanized Renilla green fluorescent protein (hGFP) vector with a 2.4-kb vector genome induced stronger GFP expression than the 293-produced one. Transduction of murine skeletal muscles with Sf9-generated rAAV5 with a 3.4-kb vector genome carrying a human secreted alkaline phosphatase (SEAP) expression cassette induced levels of SEAP more than 30 times higher than those for 293-produced vector 1 week after injection. Analysis of virion DNA revealed that in addition to a 2.4- or 3.4-kb single-stranded vector genome, Sf9-rAAV5 had more-abundant forms of approximately 4.7 kb, which appeared to correspond to the monomer duplex form of hGFP vector or truncated monomer duplex SEAP vector DNA. These results indicated that rAAV5 can be generated in insect cells, although the difference in incorporated virion DNA may induce different expression patterns of the transgene.

Alkaline Phosphatase↗