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At least 1,117 records · Page 62Linked to original sources
PubMed1988

Identification and comparison of Campoletis sonorensis virus transcripts expressed from four genomic segments in the insect hosts Campoletis sonorensis and Heliothis virescens.

The Campoletis sonorensis virus (CsV; Polydnaviridae) genome consists of at least 28 closed circular superhelical (SH) DNAs. In this study we used complete clones of four SH DNAs to analyze viral transcription both in the adult parasitic wasp host Campoletis sonorensis (Ichneumonidae) and in the lepidopteran host, Heliothis virescens (Noctuidae). CsV genes are expressed in parasitized H. virescens, but no viral transcripts had been characterized from C. sonorensis until this study. The clones of the SH DNAs B, H, M, and O1 were used to probe Northern blots of poly(A)+ RNA isolated from C. sonorensis reproductive tissue and from parasitized H. virescens larvae. All four SH DNAs hybridized to viral transcripts. SH-H,-M, and -O1 hybridized to messages expressed in both hosts. SH-B and -M hybridized to transcripts that were detected only in either C. sonorensis reproductive tissue or parasitized H. virescens larvae. These results suggest that some CsV genes are expressed in a host-specific manner. In a previous study we identified a family of imperfectly conserved tandemly repeated 540-bp repeat elements on SH-B,-H and -O1 (D. A. Theilmann and M. D. Summers, 1987 J. Virol. 61; 2589-2598). Hybridization of the 540-bp repeat regions to Northern blots showed that they were all homologous to viral transcripts. A cDNA clone of a mRNA that is transcribed from the 540-bp repeat region of SH-B was isolated from a lambda gt 10 library and completely sequenced. The sequence data revealed that the 540-bp repeat element was contained within the open reading frame of this gene. These results indicate that transcribed sequences homologous to the 540-bp repeat elements represent a second gene family to be identified within the CsV genome.

Amino Acid Sequence↗
PubMed2001

Gene transfer using human polyomavirus BK virus-like particles expressed in insect cells.

The major structural protein (VP1) of the BK polyomavirus (BKV) was expressed in the recombinant baculovirus expression system. Recombinant BKV VP1 was shown to self-assemble into virus-like particles (VLPs) with a diameter of 45-50 nm. As for other polyomaviruses, BKV VP1 has the capacity to bind to exogenous DNA. Furthermore, the potential of BKV VP1 VLPs was investigated for gene transfer into COS-7 cells using three methods for the formation of pseudo-virions: disassembly/reassembly, osmotic shock and direct interaction between VLPs and reporter plasmid DNA. The latter method was shown to be the most efficient when using linearized plasmid. Gene transfer efficiency with BKV pseudo-virions was of the same order as that observed with human papillomavirus type 16 L1 protein VLPs. In addition, it is demonstrated that cellular entry of BKV pseudo-virions is dependent on cell surface sialic acid.

Animals↗
PubMed1989

Characterization of Japanese encephalitis virus envelope protein expressed by recombinant baculoviruses.

Recombinant baculoviruses containing the coding sequences of the viral structural proteins, i.e., the capsid (C) protein, the precursor to premembrane (preM) protein, and the envelope (E) protein, as well as a nonstructural protein, NS1, of Japanese encephalitis virus (JEV) were constructed. Infection of Spodoptera frugiperda cells with these recombinant viruses produced PreM and E proteins. The E proteins synthesized by the recombinants were shown to be glycosylated and similar in size to the authentic E protein. The E protein was found on the surface of infected cells. The antigenic properties of recombinant E proteins were evaluated using a panel of monoclonal antibodies produced against JEV E protein. It was demonstrated that all of the epitopes detectable on the authentic JEV E protein were present on the recombinant E protein expressed by a recombinant baculovirus containing the coding sequence for a part of C, PreM, E, and a part of NS1 proteins. However, for E protein expressed by a recombinant baculovirus having the coding sequence of only a part of PreM, but all of E and a part of NS1, one of the flavivirus cross-reactive epitopes was not detected. Mice immunized with cells infected with the recombinant baculoviruses developed neutralization antibodies.

Animals↗
PubMed1990

Biophysical studies on the morphology of baculovirus-expressed bluetongue virus tubules.

Bluetongue virus tubules were purified from Spodoptera frugiperda cells infected with a recombinant baculovirus containing the NS1 gene from bluetongue virus serotype 10, and expressed under control of the Autographa californica nuclear polyhedrosis virus polyhedrin promoter. These tubules were subjected to a variety of chemical and physical treatments and the resulting effects on tubule morphology were examined by electron microscopy. A number of morphological similarities were noted between bluetongue virus tubules and cellular microtubules despite a lack of homology between the component proteins at the primary sequence level. A possible multistranded helical configuration is proposed for the tubule structure.

Animals↗