An analysis of herpes simplex virus gene expression during latency establishment and reactivation.
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In order to facilitate an analysis of the pattern of herpes simplex virus gene expression during latency establishment and reactivation, recombinant viruses containing the lacZ reporter gene under control of either the immediate early 110 (IE110) promoter or the latency-associated promoter have been constructed. Histochemical staining of ganglia taken from mice infected with these viruses allows for the rapid identification and quantification of sensory neurones in which these two promoters are active. Using the mouse ear model, this study demonstrates that, during the establishment of latency in vivo, IE110 promoter activity is only detectable in ganglia which provide innervation to the site of virus inoculation. Latency, however, is efficiently established not only in these ganglia, but also in adjacent ganglia whose neurones do not innervate the ear, and in which there was no evidence of IE110 expression during the acute phase of infection. This implies that replication-competent virus can efficiently establish latency in the absence of detectable IE110 expression. In addition, it has been possible to investigate viral gene expression in neurones following ganglionic explant culture by monitoring IE110 promoter-driven lacZ expression within reactivating neurones. This study shows that virus can be reactivated from all latently infected ganglia, but that reactivation appears to be more efficient from ganglia which provide innervation to the site of infection. The implications of these results for the mechanisms involved in latency establishment and reactivation are discussed. (+info)
Cutting edge: a novel viral TNF receptor superfamily member in virulent strains of human cytomegalovirus.
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The UL144 open reading frame found in clinical isolates of human CMV (HCMV) encodes a structural homologue of the herpesvirus entry mediator, a member of the TNFR superfamily. UL144 is a type I transmembrane glycoprotein that is expressed early after infection of fibroblasts; however, it is retained intracellularly. A YXXZ motif in the highly conserved cytoplasmic tail contributes to UL144 subcellular distribution. The finding that no known ligand of the TNF family binds UL144 suggests that its mechanism of action is distinct from other known viral immune evasion genes. Specific Abs to UL144 can be detected in the serum of a subset of HCMV seropositive individuals infected with HIV. This work establishes a novel molecular link between the TNF superfamily and herpesvirus that may contribute to the ability of HCMV to escape immune clearance. (+info)
Immunization against genital herpes with a vaccine virus that has defects in productive and latent infection.
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An effective vaccine for genital herpes has been difficult to achieve because of the limited efficacy of subunit vaccines and the safety concerns about live viruses. As an alternative approach, mutant herpes simplex virus strains that are replication-defective can induce protective immunity. To increase the level of safety and to prove that replication was not needed for immunization, we constructed a mutant herpes simplex virus 2 strain containing two deletion mutations, each of which eliminated viral replication. The double-mutant virus induces protective immunity that can reduce acute viral shedding and latent infection in a mouse genital model, but importantly, the double-mutant virus shows a phenotypic defect in latent infection. This herpes vaccine strain, which is immunogenic but has defects in both productive and latent infection, provides a paradigm for the design of vaccines and vaccine vectors for other sexually transmitted diseases, such as AIDS. (+info)
Fibroblast growth factor 2 retargeted adenovirus has redirected cellular tropism: evidence for reduced toxicity and enhanced antitumor activity in mice.
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Adenovirus (Ad) have been used as vectors to deliver genes to a wide variety of tissues. Despite achieving high expression levels in vivo, Ad vectors display normal tissue toxicity, transient expression, and antivector immune responses that limit therapeutic potential. To circumvent these problems, several retargeting strategies to abrogate native tropism and redirect Ad uptake through defined receptors have been attempted. Despite success in cell culture, in vivo results have generally not shown sufficient selectivity for target tissues. We have previously identified (C. K. Goldman et al., Cancer Res., 57: 1447-1451, 1997) the fibroblast growth factor (FGF) ligand and receptor families as conferring sufficient specificity and binding affinity to be useful for targeting DNA in vivo. In the present studies, we retargeted Ad using basic FGF (FGF2) as a targeting ligand. Cellular uptake is redirected through high-affinity FGF receptors (FGFRs) and not the more ubiquitous lower-affinity Ad receptors. Initial in vitro experiments demonstrated a 10- to 100-fold increase in gene expression in numerous FGFR positive (FGFR+) cell lines using FGF2-Ad when compared with Ad. To determine whether increased selectivity could be detected in vivo, FGF2-Ad was administered i.v. to normal mice. FGF2-Ad demonstrates markedly decreased hepatic toxicity and liver transgene expression compared with Ad treatment. Importantly, FGF2-Ad encoding the herpes simplex virus thymidine kinase (TK) gene transduces Ad-resistant FGFR+ tumor cells both ex vivo and in vivo, which results in substantially enhanced survival (180-260%) when the prodrug ganciclovir is administered. Because FGFRs are up-regulated on many types of malignant or injured cells, this broadly useful method to redirect native Ad tropism and to increase the potency of gene expression may offer significant therapeutic advantages. (+info)
The nature of the principal type 1 interferon-producing cells in human blood.
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Interferons (IFNs) are the most important cytokines in antiviral immune responses. "Natural IFN-producing cells" (IPCs) in human blood express CD4 and major histocompatibility complex class II proteins, but have not been isolated and further characterized because of their rarity, rapid apoptosis, and lack of lineage markers. Purified IPCs are here shown to be the CD4(+)CD11c- type 2 dendritic cell precursors (pDC2s), which produce 200 to 1000 times more IFN than other blood cells after microbial challenge. pDC2s are thus an effector cell type of the immune system, critical for antiviral and antitumor immune responses. (+info)
Mutant cells that do not respond to interleukin-1 (IL-1) reveal a novel role for IL-1 receptor-associated kinase.
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Mutagenized human 293 cells containing an interleukin-1 (IL-1)-regulated herpes thymidine kinase gene, selected in IL-1 and gancyclovir, have yielded many independent clones that are unresponsive to IL-1. The four clones analyzed here carry recessive mutations and represent three complementation groups. Mutant A in complementation group I1 lacks IL-1 receptor-associated kinase (IRAK), while the mutants in the other two groups are defective in unknown components that function upstream of IRAK. Expression of exogenous IRAK in I1A cells (I1A-IRAK) restores their responsiveness to IL-1. Neither NFkappaB nor Jun kinase is activated in IL-1-treated I1A cells, but these responses are restored in I1A-IRAK cells, indicating that IRAK is required for both. To address the role of the kinase activity of IRAK in IL-1 signaling, its ATP binding site was mutated (K239A), completely abolishing kinase activity. In transfected I1A cells, IRAK-K239A was still phosphorylated upon IL-1 stimulation and, surprisingly, still complemented all the defects in the mutant cells. Therefore, IRAK must be phosphorylated by a different kinase, and phospho-IRAK must play a role in IL-1-mediated signaling that does not require its kinase activity. (+info)
Neonatal herpes simplex virus infections: HSV DNA in cerebrospinal fluid and serum.
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AIM: To investigate the diagnostic potential of herpes simplex virus (HSV) DNA in cerebrospinal fluid and serum; to correlate the findings with outcome in the child and with type of maternal infection. METHODS: Cerebrospinal fluid and serum specimens from 36 children with verified neonatal HSV infections, diagnosed between 1973 and 1996, were examined using the polymerase chain reaction technique (PCR). RESULTS: In 21 children for whom both cerebrospinal fluid and sera were available, HSV DNA was found in one or both specimens in 19 (90%). Overall, HSV DNA was found in the cerebrospinal fluid of 74% of 27 children, and in the sera of 20 out of 30 children (67%). In two children HSV DNA was not demonstrable in either serum or cerebrospinal fluid. In sequential specimens from four children, the persistence of HSV DNA after the end of intravenous treatment was associated with a poor prognosis. CONCLUSIONS: These findings indicate that HSV DNA detection in CSF and serum is highly sensitive for the diagnosis of neonatal HSV infections but does not replace the detection of virus in other locations using virus isolation and antigen detection. (+info)
Separation of submicron bioparticles by dielectrophoresis.
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Submicron particles such as latex spheres and viruses can be manipulated and characterized using dielectrophoresis. By the use of appropriate microelectrode arrays, particles can be trapped or moved between regions of high or low electric fields. The magnitude and direction of the dielectrophoretic force on the particle depends on its dielectric properties, so that a heterogeneous mixture of particles can be separated to produce a more homogeneous population. In this paper the controlled separation of submicron bioparticles is demonstrated. With electrode arrays fabricated using direct write electron beam lithography, it is shown that different types of submicron latex spheres can be spatially separated. The separation occurs as a result of differences in magnitude and/or direction of the dielectrophoretic force on different populations of particles. These differences arise mainly because the surface properties of submicron particles dominate their dielectrophoretic behavior. It is also demonstrated that tobacco mosaic virus and herpes simplex virus can be manipulated and spatially separated in a microelectrode array. (+info)