摘要:

Previous studies have shown that herpes simplex virus (HSV) type 2 (HSV-2) can be maintained in a latent state in a limited number of cells by elevating the incubation temperature after treatment of HSV-infected human fetus lung fibroblast cells with metabolic inhibitors. Superinfection with human cytomegalovirus (HCMV) of latently infected cells maintained at the elevated temperature reactivated latent virus. In addition, superinfection with temperature-sensitive mutants indicated that reactivation of latent HSV in vitro did not require the expression of late gene function(s) of the superinfecting virus. We now report the (i) design of an in vitro HSV-2-latency system in which a higher percentage of cells contain a virus genome that can be activated; and (ii) subsequent use of this system to further characterize the virus activation process. Superinfection with a transcription-negative temperature-sensitive mutant of HSV type 1 (HSV-1) did not reactivate HSV-2-replication, suggesting that adsorption and penetration of the superinfecting virus were not sufficient for reactivation of the latent virus. Furthermore, superinfection with HSV-1 in the presence of (E)-5-(2-bromovinyl)-2’-deoxyuridine did not reactivate HSV-2 replication, suggesting that the expression of the immediate-early gene products are not sufficient for HSV-2 reactivation. Collectively, these data suggest that in addition to the expression of immediate-early gene function(s) at least a subset of early HSV-1 gene products are required for reactivation of latent HSV-2 in vitr

ISSN:0300-5526    

DOI:10.1159/000149730

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Mice fed a basal diet which contained 0.018% ciclosporin (CsA) achieved immunosuppressive blood levels of 1,400–2,200 ng/ml. Observations for 84 days of mice placed on this diet and infected at the same time with murine cytomegalovirus (MCMV) showed elevated virus titers and more widespread infection of various organs. An enhancing effect on acute MCMV infection measured by virus titers in the spleen 5 days after infection was evident only after 14 days of prior CsA ingestion. In groups of mice which were already infected with virus for 14 or 21 days, 14 days of CsA ingestion was needed before enhanced MCMV titers were noted in organs tested. Pretreatment with CsA of donor mice, which provided MCMV-specific immune spleen cells in passive protective experiments, eliminated the protective effect of transferred cells for recipient mice challenged with MCMV. These results suggest that CsA enhanced virus titers and helped maintain chronic persistent infection in certain organs by affecting the development or function of immune cells. Regardless of whether CsA was given before or after virus infection, about 2 weeks of CsA administration was required before elevation of virus titer was observe

ISSN:0300-5526    

DOI:10.1159/000149731

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The validity of the model proposed by Cavalier-Smith for the replication of linear, single-stranded DNA molecules was tested by using subgenomic DNA termini isolated from adeno-associated virus (AAV), a defective parvovirus. In purified DNA replication systems, the terminal hairpin structure of AAV DNA with a 3’-OH end was shown to prime the synthesis of the daughter DNA strand, which was covalently linked to the parental strand. This resulted in the synthesis of a duplex DNA structure with a terminal hairpin. The availability of such a hairpin structure should facilitate the isolation and characterization of the pivotal enzyme, the putative nickase, for the replication of AAV DN

ISSN:0300-5526    

DOI:10.1159/000149732

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The budding process of human immunodeficiency virus (HIV), strain LAV, starts with the formation of a crescent electron-dense layer directly underneath the cell membrane of infected CCRF-CEM cells. After completion of the formation of the circle of inner dense layer, immature virions with an electron-lucent center are released from the cells. Serial thin sections and stereo observation of thick sections showed that most of the immature virions adjacent to the cell surface had already come off the cell and some still had very thin connections to the cell. However, on rare occasions, virions at an intermediate stage between immature stage and mature virions with bar-shaped electron-dense cores were observed. Virions with dense cores were never observed to be connected to the cell surface. These observations support the idea that the last step of the maturation of HIV occurs outside the cell and that the electron-dense core seems to develop by rearrangement and dispersion of the substance of the inner dense layer of immature virions.

ISSN:0300-5526    

DOI:10.1159/000149733

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The localization of the major cytomegalovirus glycoprotein, both in the viral particle and in the cell membrane, was studied by means of indirect immunofluorescence and immunoelectron microscopy using a guinea pig anti-glycoprotein hyperimmune serum recently obtained by Gonczol et al. [1986]. By indirect immunofluorescence a slight and uneven positivity was observed on the plasma membrane of unfixed cells starting from 72 h postinfection (p.i.) until the end of our observation time (7 days p.i.). At immunoelectron microscopy the plasma membrane proved positive only where the virus and dense bodies budded through the membrane to form their own envelope. Extracellular viral particles (both viruses and dense bodies) appeared very strongly labeled on the external surface.

ISSN:0300-5526    

DOI:10.1159/000149734

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Nine viruses antigenically related to Hantaan virus that were isolated from various rodents in several countries and from a patient were examined by immunoprecipitation and by hemagglutination inhibition (HI). The immunoprecipitation tests were done with a monoclonal antibody that reacted with glycoprotein G2 and an antibody against a nucleocapsid protein. The viruses were classified into four subtypes on the basis of the molecular weights of their precipitated polypeptides and the pattern of results of the HI tests.

ISSN:0300-5526    

DOI:10.1159/000149735

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The bee venom peptide melittin activated the virion transcriptase activity of three vesiculoviruses with preservation of virion structure. The kinetics of RNA synthesis were similar to those observed with purified transcribing nucleoprotein (TNP) preparations. Six temperature-sensitive host range (tdC&Egr;) mutants of Chandipura virus displayed 1.7- to 5.5-fold greater efficiencies of transcription at 39° with melittin-permeabilized virions in comparison with TNP preparations. Comparative study of other host range mutants (tdCE3 and tsB1) of vesicular stomatitis virus (VSV) New Jersey and a thermosensitive polymerase mutant (tsG114) of VSV Indiana suggested that the enhanced transcription at 39° associated with melittin-activated tdCE mutants was due to the retention of host factors in the virion

ISSN:0300-5526    

DOI:10.1159/000149736

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

cDNA of the subgenomic messenger RNA (RNA 4) of alfalfa mosaic virus was ligated in both orientations into plasmids containing the bacteriophage SP 6 promoter. Upon transcription in vitro these plasmids yielded synthetic full-length complementary RNA and messenger-sense RNA. The complementary RNA contained an open reading frame of 417 nucleotides; the messenger-sense RNA encodes the virus coat protein. No translation products from the complementary RNA were detected in a wheat germ translation system, a reticulocyte lysate translation system, or Xenopus oocytes, whereas the messenger sense RNA was very active in these translation systems.

ISSN:0300-5526    

DOI:10.1159/000149737

出版商:S. Karger AG    

年代:1987

数据来源: Karger