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At least 1,261 records · Page 70Linked to original sources
PubMed1986

Studies on Autographa californica nuclear polyhedrosis virus replication in Spodoptera littoralis cells including virus-induced protein synthesis.

The replication of the Autographa californica nuclear polyhedrosis virus in Spodoptera littoralis cells has been investigated. Various cytopathic changes were detected by light and electron microscopy and progeny enveloped virus particles, some occluded within polyhedra, were later seen in the nucleus of infected cells. Infectious virus was released into the growth medium and increased exponentially from ca. 10 to 24 hours post infection and then slowly increased over the next 4 days. In comparison, virus was released ca. 3.5 hours earlier from Spodoptera frugiperda cells. Total rates of DNA and protein synthesis were drastically reduced during the late stages of virus replication when cell death was occurring. By ca. 18 hours post infection, a clear switch from host to virus induced protein synthesis had occurred and a total of 39 virus-induced polypeptides of M.W. 12 to 120 X 10(3) were detected. These included polyhedrin of M.W. 33 X 10(3), which was particularly prominent during the late stages of virus replication, and a major virus structural protein of M.W. 42 X 10(3).

Animals↗
PubMed2003

MHC class I up-regulation by flaviviruses: Immune interaction with unknown advantage to host or pathogen.

In contrast to many other viruses that escape from cytotoxic T cell recognition by down-regulating major histocompatibility complex class I-restricted antigen presentation, flavivirus infection of mammalian cells up-regulates cell surface expression of major histocompatibility complex class I molecules. Two putative mechanisms for flavivirus-induced major histocompatibility complex class I up-regulation, one via activation of the transcription factor NF-kappaB, the second by augmentation of peptide import into the lumen of the endoplasmic reticulum, are reviewed, and the biological effect of the flavivirus-mediated phenomenon on target cell recognition by natural killer and cytotoxic T cells is addressed. Finally, we speculate on the physiological role of flavivirus-mediated modulation of major histocompatibility complex class I antigen presentation in the context of the biology of flavivirus transmission between the vertebrate host and arthropod vector and suggest that it may represent a strategy for immune evasion from the natural killer cell response or, alternatively, that up-regulation of major histocompatibility complex class I is a by-product of flavivirus replication without significance for virus growth.

Animals↗
PubMed1977

DNA contained by two densonucleosis viruses.

The DNA contained by particles of densonucleosis viruses 1 and 2 were analyzed within the particle, and properties of DNA extracted from these particles were determined. The DNA appears to exist as a single-stranded molecule with limited secondary structure within particles, as assessed by spectral changes induced by formaldehyde, melting profiles, and circular dichroism studies. The single-stranded DNA had an apparent molecular weight of 1.9 X 10(6) to 2.2 X 10(6) as assessed by differences in the molecular weight of virus particles and top component and percentage of nucleic acid. DNA extracted from virus particles in low-salt buffers possessed properties typical of a single-stranded molecule. Double-stranded DNA could be extracted from virus particles under appropriate high salt and elevated temperature. The linear double-stranded DNA extracted from both viruses had a molecular weight of about 3.9 X 10(6) to 4.1 ZX 10(6) determined by neutral sedimentation and electron microscopy and an equivalent genome size determined by reassociation kinetics. About 87% of the DNA was homologous between the two viruses.

Animals↗
PubMed1979

An entomopoxvirus from Oncopera alboguttata (Lepidoptera: Hepialidae) in Australia.

A new entomopoxvirus has been isolated from field-collected larvae of Oncopera alboguttata at Ebor, New South Wales, Australia. The ovoid proteinaceous virus-containing bodies measured about 8 x 6 microns and contained up to about 17 centrally-embedded virus-free spindles and up to about 180 occluded virus particles. The virus particle had a beaded outer membrane and measured about 390 x 270 x 230 nm. The particle contained a single lateral body and a unilaterally concave core which in longitudinal section measured 320 x 80 nm. Dissolution of inclusion body and spindle protein to release virus particles occurred in carbonate/thioglycollate buffer at pH greater than 12.0. It is postulated that this virus has recently evolved from similar viruses in soil inhabiting coleopteran larvae.

Animals↗
PubMedDate not supplied

[Properties of the nuclear polyhedrosis virus].

Four passages of Barathra brassicae L nuclear polyhedrosis virus (NPV) in Heliothis armigera Hbn caterpillars were carried out. B. brassicae NPV was found to be highly infective for caterpillars of both species. When H. armigera caterpillars were infected with B. brassicae NPV, reproduction of the latter occurred alongside with the induction of H. armigera latent virus. In subsequent passages the latent virus replaced the foreign NPV. It was noted in mixed infection that in the 2nd passage the activity of NPV decreased apparently due to interference of the viruses.

Animals↗
PubMed1998

Evidence for two small viruses persistently infecting established cell lines of Phthorimaea operculella, deriving from embryos of the potato tuber moth.

Two small viruses were isolated from established cell lines of P. operculella deriving from embryos. The first one probably related to the Nodaviridae family, is a 30 nm in diameter icosahedral virus, with a bisegmented RNA genome and a single polypeptide of 39 kilodaltons. The second one related to the Parvoviridae family, is a 25 nm in diameter icosahedral virus with a DNA genome and a capsid constituted of 4 polypeptides of respectively, 90,000; 64,000; 56,000 and 43,500 daltons. The two viruses probably chronically infect the cell lines and may be consider latent viruses.

Animals↗