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At least 1,423 records · Page 79Linked to original sources
PubMed1983

A functional cyclooxygenase enzyme is not required for mediation of the pleiotropic effects of human alpha or beta interferon.

Aspirin, indomethacin, and phenbutazone at 50 microM concentration inhibit cyclooxygenase in cultured human foreskin fibroblasts as evidenced by the suppression of the major prostaglandin species which accumulate in the culture medium. In contrast to data reported for mouse interferon on target mouse cells, these agents have no effect on the induction of antiviral activity by human alpha or beta interferons. Similarly, these agents have no effect on interferon induced inhibition of cell growth in vitro or on interferon induced natural killer cell activity.

Aspirin↗
PubMed1979

Characterization of a new isolate of poliovirus defective interfering particles.

An independent isolate of poliovirus defective interfering particles has been analyzed. These particles, designated DI(A), are apparently analogous to the DI particles described by Baltimore and co-investigators. Electron microscopic heteroduplex analysis reveals that the DI(A) isolate is a mixture of deletion mutants which changes with passage level. The DI(A) population consists of at least five distinct deletion mutants, including one double deletion. Electron microscopic mapping of the deleted regions indicates that most, if not all, of the viral capsid region can be deleted. Despite this heterogeneity, the mutant genomes are quite similar in physical size. We propose a model which suggests that the observed properties of poliovirus DI genomes reflect selective pressures extant during the amplification of the mutant genome. According to this model, only those deleted genomes which retain a minimal size and the capacity to synthesize a functional viral polymerase will replicate successfully in a mixed infection. Furthermore, this model proposes a mechanism for the enrichment of poliovirus DI genomes and an explanation for the low level of complementation observed in mixed infections of picornaviruses.

Chromosome Deletion↗
PubMed1992

Infectious defective interfering particles of VSV from transcripts of a cDNA clone.

The generation of infectious defective interfering (DI) particles of vesicular stomatitis virus (VSV) entirely from cDNA clones is reported. Bacteriophage T7 RNA polymerase was used to direct the transcription of a complete negative-stranded genomic RNA from a cDNA clone of a VSV DI RNA in cells simultaneously expressing the five VSV proteins from separately transfected cDNA clones. The negative-stranded transcript was encapsidated with N protein, replicated by the VSV polymerase, and the replicated RNAs were assembled and budded to yield infectious DI virions. No helper VSV was required. Replication occurred at high levels and was assayed by direct biochemical means. An exact 3' terminus of the initial transcript, which was generated by autolytic cleavage using a ribozyme from hepatitis delta virus, was critical for replication.

Base Sequence↗
PubMed1994

Identification and sequence of an accessory factor required for activation of the human interferon gamma receptor.

Human chromosomes 6 and 21 are both necessary to confer sensitivity to human interferon gamma (Hu-IFN-gamma), as measured by induction of class I human leukocyte antigen (HLA) and protection against encephalomyocarditis virus (EMCV) infection. Whereas human chromosome 6 encodes the Hu-IFN-gamma receptor, human chromosome 21 encodes accessory factors for generating biological activity through the Hu-IFN-gamma receptor. Probes from a genomic clone were used to identity cDNA clones expressing a species-specific accessory factor. These cDNA clones are able to substitute for human chromosome 21 to reconstitute the Hu-IFN-gamma receptor-mediated induction of class I HLA antigens. However, the factor encoded by the cDNA does not confer full antiviral protection against EMCV, confirming that an additional factor encoded on human chromosome 21 is required for reconstitution of antiviral activity against EMCV. We conclude that this accessory factor belongs to a family of such accessory factors responsible for different actions of IFN-gamma.

Amino Acid Sequence↗
PubMed1988

Comparative study of two strains of Bovid herpesvirus-4.

Two strains of Bovid herpesvirus-4 (BHV-4), i.e. the prototype strain DN-599, obtained from a steer suffering of a respiratory disease, and the strain 85/BH 16TV, originated from a cow with vulvovaginitis, were compared in studies which included restriction endonuclease analysis, experimental infection and reciprocal cross protection tests. The restriction endonuclease analysis revealed that the resultant DNA patterns of the isolates were generally similar with only a difference in one fragment. The two strains were capable of causing respiratory tract infection in calves, even if they displayed a different level of virulence: the strain 85/BH 16TV being the most virulent while the strain DN-599 the least. The two viral strains were mutually protective in that the calves were generally found to be refractory to challenge inoculation with either the homologous or the heterologous virus. Finally, both viral strains failed to evoke the production of neutralizing antibody in the experimental calves.

Animals↗
PubMed1992

Effects in calves of mixed infections with bovine viral diarrhea virus and several other bovine viruses.

The objective of this study was to verify whether a mixed infection in calves with bovine viral diarrhea virus (BVDV) and other bovine viruses, such as bovid herpesvirus-4 (BHV-4), parainfluenza-3 (PI-3) and infectious bovine rhinotracheitis (IBR) virus, would influence the pathogenesis of the BVDV infection sufficiently to result in the typical form of mucosal disease being produced. Accordingly, two experiments were undertaken. In one experiment calves were first infected with BVDV and subsequently with BHV-4 and IBR virus, respectively. The second experiment consisted in a simultaneous infection of calves with BVDV and PI-3 virus or BVDV and IBR virus. From the first experiment it seems that BVDV infection can be reactivated in calves by BHV-4 and IBR virus. Evidence of this is that BVDV, at least the cytopathic (CP) strain, was recovered from calves following superinfection. Moreover, following such superinfection the calves showed signs which could most likely be ascribed to the pathogenetic activity of BVDV. Superinfection, especially by IBR virus, created a more severe clinical response in calves that were initially infected with CP BVDV, than in those previously given the non-cytopathic (NCP) biotype of the virus. Simultaneous infection with PI-3 virus did not seem to modify to any significant extent the pathogenesis of the experimentally induced BVDV infection whereas a severe clinical response was observed in calves when simultaneous infection was made with BVDV and IBR virus.

Animals↗
PubMedDate not supplied

Physical dependence to morphine diminishes the interferon response in mice.

Morphine pellet implantation in mice was demonstrated to diminish resistance to encephalomyocarditis virus infections. The variations in the response to three different interferon (IFN) inducers--Newcastle disease virus, Escherichia coli lipopolysaccharide and a tilorone analogue--were evaluated. A close relationship between morphine dependence and IFN response was detected. A clear inhibition in IFN induction appeared as a concomitant phenomenon with the syndrome of morphine dependence. In the response intensity, the mice strain tested was more important than the total drug dose in the pellet. This effect of morphine on IFN responses presented a characteristic age-related pattern and, perhaps, may also be influenced by the H-2 murine phenotype.

Animals↗
PubMed1986

Vero cells persistently infected with Tacaribe virus: role of interfering particles in the establishment of the infection.

Eight Vero cell sublines (Vero T) persistently infected with wild type Tacaribe virus replicated in different hosts were established. In order to unravel the mechanism involved in the initiation and maintenance of persistence, the properties of virus shed by the sublines and the presence of interfering particles (IP) were analyzed. During the course of infection, persistent virus (Tac-pi) underwent mutations although no consistent pattern of virus evolution was observed. ts mutants were isolated from two Vero T sublines, whereas a slow growth variant was shed by another. The remaining sublines released virus resembling wt parental virus. Except for Vero T1 sublines, Vero T cultures shed no detectable IP. These results emphasize the point that neither the emergence of virus mutants nor the synthesis of IP is essential for the maintenance of the persistent state. To define the role of IP in the initiation of persistence, coinfection experiments with a characterized inoculum were performed. For that purpose, attempts were made to obtain IP stocks free from pfu by serial transfers of undiluted virus. Neither enrichment nor amplification of IP occurred, and virus stocks were freed of infectious virus by UV irradiation. If normal Vero cells were infected with Tac-pi virus released by Vero T2, Vero T3, Vero T4, Vero T5, Vero T6, Vero T7 and Vero T10 sublines, a complete destruction of the monolayer without cell recovery was observed. In contrast, parental and Vero T1 viruses always originated persistently infected sublines. Similarly, the addition of IP to virus inocula constituted by Tac-pi viruses released by Vero T2, Vero T3, Vero T4, Vero T5, Vero T6, Vero T7 and Vero T10 sublines gave rise to persistently infected cultures. These results suggest that although IP are not important by themselves in the maintenance of persistence, they play a major role in initiation.

Animals↗
PubMed1994

Intracellular immunization of mosquito cells to LaCrosse virus using a recombinant Sindbis virus vector.

A cDNA of the small RNA genome segment of La Crosse (LAC) virus was inserted, in an antisense orientation, into a double subgenomic Sindbis (dsSIN) virus expression vector generating pTE/3'2J/ANTI-S (15,000bp). In vitro transcription of the pTE/3'2J/ANTI-S template generated genomic RNA that was electrotransfected into BHK-21 cells to produce virus. Northern blot analysis of RNA isolated from infected Aedes albopictus (C6/36) cells showed that the TE/3'2J/ANTI-S virus produced a subgenomic mRNA of the appropriate size, indicating transcription of the LAC cDNA segment. C6/36 cells were infected with either TE/3'2J/ANTI-S, TE/3'2J (a dsSIN virus with no LAC insert), or wild type Sindbis (SIN, strain AR339) viruses and subsequently challenged with LAC virus. LAC virus titers were determined using a capture antibody ELISA. Mosquito cells infected with TE/3'2J/ANTI-S virus yielded at least 4 log10 TCID50/ml less LAC virus than cells infected with either TE/3'2J or AR339 SIN viruses. The use of the infectious SIN virus expression vectors provides a novel approach for high level cytoplasmic expression of genes or sequences of interest in arthropod cells, and for evaluating strategies for intracellular immunization against arboviruses.

Aedes↗
PubMed1990

Inhibition of receptor-mediated cellular entry of viruses including HIV: a perspective on further researches on chemotherapy in viral diseases including AIDS.

Receptor-mediated endocytosis is a well recognized process by which many cells internalize and intracellularly process important biological molecules including viruses. The present hypothesis, addressing receptor-mediated cellular entry of viruses including HIV, describes a perspective of further basic studies seen through the current knowledge about pharmacological control of various steps of receptor-mediated endocytosis of different ligands and viruses as well. It proposes a list of more than 20 chemicals, targeted at inhibition of viral internalization and viral release into the cytoplasm, via their action(s) on transglutaminase, calmodulin, protein kinase C, and intraendosomal pH. It is cautiously suggested that a proper study of these chemicals may reveal some therapeutic values of their own in some viral diseases including AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1980

Bacteriophage lambda cloning vehicles for studies of genetic recombination.

A pair of bacteriophage lambda cloning vehicles has been constructed for use in studies of genetic recombination. These phages, lambda rva and lambda rvb, have the following properties: (1) Each vector has a single HindIII site in the immunity region, at which segments of DNA can be inserted. (2) These HindIII sites are flanked by selectable markers with the following phenotypes: Spi+/- (Fec+/-) to the left, and imm lambda or imm434 to the right. (3) There is essentially no sequence homology between the two phages in this region, so recombination of the markers at reasonable frequency depends on the presence of homologous inserts at the HindIII sites. As a consequence, recovered recombinants must have resulted from a crossover event within the insert DNA. Restriction enzyme maps of the vectors have been determined. Variants of the original vectors have been isolated which permit separate examination of the viral (Red) and bacterial (Rec) generalized recombination mechanisms, and which provide a standard interval to which frequencies of recombination in cloned DNAs can be compared.

Bacteriophage lambda↗
PubMed1993

Transgenic plants that express genes including the 3' untranslated region of the turnip yellow mosaic virus (TYMV) genome are partially protected against TYMV infection.

In order to evaluate new possibilities for protecting plants against virus infection by interference with viral replication, two chimeric genes were constructed in which the (+) strand 3'-terminal 100 nucleotides (nt) of the noncoding region of the turnip yellow mosaic virus (TYMV) genome were placed downstream from the sense or antisense cat coding region. The two chimeric genes were then introduced into the genome of rapeseed (Brassica napus) using an Agrobacterium rhizogenes vector system. Plants expressing high levels of either chimeric gene showed partial protection against infection by TYMV RNA or virions. One interesting feature of the protection is that a proportion of the inoculated transgenic plants does not become infected. Protection was overcome when the inoculum concentration was increased. RNA complementary to the initial transcript was detected after infection.

Base Sequence↗
PubMed1989

Natural infection with the porcine respiratory coronavirus induces protective lactogenic immunity against transmissible gastroenteritis.

Our objective was to evaluate the level of passive protection against transmissible gastroenteritis (TGE) among 57 newborn piglets nursing from seven seropositive sows previously naturally infected with porcine respiratory coronavirus (PRCV). After challenge exposure we observed mortality rates of 44% for litters of seven PRCV-infected sows, 40% for litters of four sows orally immunized with the attenuated TGEV strain Nouzilly, and 91% for litters of seven seronegative susceptible sows. A blocking ELISA with two appropriate monoclonal antibodies distinguished serological responses of PRCV-infected sows from those of TGEV-immunized sows. The results suggest that natural infection of the sow with PRCV may induce a degree of protective lactogenic immunity against TGE.

Animals↗
PubMed2005

Polybiguanides, particularly polyethylene hexamethylene biguanide, have activity against human immunodeficiency virus type 1.

Polyhexamethylene biguanide (PHMB) is a polybiguanide (PBG) oligomer with antimicrobial activity that is used extensively and safely as a disinfectant. The reported mechanism of PHMB antimicrobial activity, which involves interactions with cell membrane components, suggested that PHMB or other PBG-based compounds might also have antiviral or virucidal activity against the human immunodeficiency virus type 1 (HIV-1). PHMB had modest in vitro activity against both cell-free and cell-associated HIV-1, as well as the ability to interfere with viral binding and entry. However, PHMB was comparable in cytotoxicity to the spermicidal agent nonoxynol-9 (N-9), a compound that has been characterized in previous studies as generally cytotoxic and detrimental to cervicovaginal epithelial integrity. To identify structural variants of PHMB with greater anti-HIV-1 activity and/or less cytotoxicity, modified versions of PHMB incorporating length changes in the hydrocarbon linker units were synthesized and evaluated for in vitro cytotoxicity and inhibition of HIV-1 infectivity. These experiments demonstrated that the PHMB variant polyethylene hexamethylene biguanide (PEHMB) was just as active against HIV-1 as PHMB, yet was much less cytotoxic than either N-9 or PHMB, resulting in an in vitro therapeutic index (TI) approximately 114-fold greater than the TI of N-9. PEHMB, which has been identified in these studies as a promising microbicidal candidate in this family of compounds, will be the focus of further in vitro and in vivo evaluations of anti-HIV-1 activity, toxicity, and mechanisms of action.

Anti-HIV Agents↗