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At least 1,297 records · Page 72Linked to original sources
PubMed1989

Studies on the control region of the p10 gene of the Autographa californica nuclear polyhedrosis virus.

5' deletion mutants of the Autographa californica nuclear polyhedrosis virus very late p10 gene promoter have been prepared and subjected to a transient expression assay in infected Spodoptera frugiperda cells. The control plasmid contained the chloramphenicol acetyltransferase (CAT) reporter gene under the control of the p10 promoter, which was included in a 230 bp sequence upstream from the p10 translation initiation codon. The control plasmid also contained a segment of the hr5 enhancer downstream from the CAT gene. Promoter activity was unaffected by 5' deletion to position -77, which lies about 11 bp upstream from the p10 cap site. However, deletion of 12 more bp completely eliminated p10 promoter activity. Thus, the 5' border of the p10 promoter lies downstream from position -77, and the region between positions -77 and -65 contains an element that is important to promoter activity. This is the region that is conserved near the cap sites of late baculovirus genes. Our studies also show that transient expression of CAT under the control of the p10 promoter and hr5 enhancer is higher when transfection occurs prior to infection by virus.

Animals↗
PubMed1985

Baculovirus-mediated expression of bacterial genes in dipteran and mammalian cells.

A recombinant baculovirus containing the Escherichia coli chloramphenicol acetyltransferase (CAT) gene under the control of the Rous sarcoma virus long terminal repeat promoter and the E. coli beta-galactosidase gene under the control of the very late baculoviral polyhedrin promoter was used to determine if Autographa californica nuclear polyhedrosis virus, a baculovirus of Lepidoptera, can enter and express viral DNA in dipteran (Drosophila sp.) and mammalian (Mus sp.) cells that are considered refractory to baculovirus replication. Following infection, CAT gene expression was observed in both dipteran and mammalian cells, but expression in the mammalian cell line was less than 0.05% of that observed in either dipteran or lepidopteran cells. Although the level of CAT gene expression was similar in permissive lepidopteran and nonpermissive dipteran cells, expression of beta-galactosidase activity from the late polyhedrin promoter in dipteran or mammalian cells was less than 0.3% of the levels observed in lepidopteran cells. These results indicate that foreign gene expression in nonpermissive cells is promoter dependent and that late viral gene expression is restricted in these cells. The Rous sarcoma virus long terminal repeat allows substantial CAT gene expression in both a D. melanogaster cell line and Aedes aegypti midgut cells. Baculovirus DNA undergoes a limited number of replications in Drosophila cells. The results are relevant to baculovirus host range, the safety of baculoviruses as pesticides, and the development of baculovirus pesticides with expanded host ranges.

Acetyltransferases↗
PubMed1987

Induction of salivation in biting midges and mosquitoes, and demonstration of virus in the saliva of infected insects.

Culicoides biting midges and Aedes aegypti (Linnaeus) mosquitoes were induced to salivate by the topical application of pilocarpine, neostigmine, malathion and dimethoate; of these, malathion was the most effective. Drops of saliva produced by virus-infected midges and mosquitoes were shown to contain virus. The method could be used to demonstrate transmission in insects infected with a variety of pathogens.

Aedes↗
PubMed1989

Characterization of a novel human respiratory syncytial virus chimeric FG glycoprotein expressed using a baculovirus vector.

Human respiratory syncytial virus (RSV) codes for two glycoproteins (F and G) which have been shown to the major targets for the host antibody response. We have expressed a novel chimeric glycoprotein (FG) in insect cells using a baculovirus vector. The chimeric glycoprotein contains the signal and extracellular regions of the RSV F glycoprotein linked to the extracellular region of the RSV G glycoprotein. Beginning at the amino terminus, the chimeric glycoprotein consists of amino acids 1 to 489 from RSV F followed by amino acids 97 to 279 from RSV G. The chimeric FG glycoprotein did not contain an anchor region and was efficiently secreted into the medium of recombinant baculovirus-infected insect cells. The FG glycoprotein ranged in size from 69K to 91K and was heterogeneous with respect to isoelectric point. The cleavage site present on the F glycoprotein was recognized on the chimeric FG, and the glycoprotein appeared to be antigenically similar to the native RSV F and G glycoproteins.

Antigens, Viral↗
PubMed1990

Retroviral DNA integration directed by HIV integration protein in vitro.

Efficient retroviral growth requires integration of a DNA copy of the viral RNA genome into a chromosome of the host. As a first step in analyzing the mechanism of integration of human immunodeficiency virus (HIV) DNA, a cell-free system was established that models the integration reaction. The in vitro system depends on the HIV integration (IN) protein, which was partially purified from insect cells engineered to express IN protein in large quantities. Integration was detected in a biological assay that scores the insertion of a linear DNA containing HIV terminal sequences into a lambda DNA target. Some integration products generated in this assay contained five-base pair duplications of the target DNA at the recombination junctions, a characteristic of HIV integration in vivo; the remaining products contained aberrant junctional sequences that may have been produced in a variation of the normal reaction. These results indicate that HIV IN protein is the only viral protein required to insert model HIV DNA sequences into a target DNA in vitro.

Animals↗