Natural immunity of Ghanaian children to polio and coxsackieviruses. Brief report.
Explore the source record for details and available documents.
Age Factors↗
SEARCH · Search PubMed
Results for “VIRAL INTERFERENCE”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
"Issyk-Kul" virus, a new arbovirus isolated from bats and Argas (Carios) vespertilionis (Latr., 1802) in the Kirghiz S.S.R. Brief report.
Explore the source record for details and available documents.
Animals↗
Heterologous resistance to superinfection by louping ill virus persistently infected cell cultures.
Louping ill virus, a tick-borne arbovirus readily established a persistent infection in porcine kidney (PS) cells after initially inducing minor cytopathic changes. Nucleotide sequence analysis of the envelope glycoprotein of the viral RNA recovered from the persistently infected cells showed no changes as compared with the virus used to establish persistent infections. More than 80 per cent of the cells contained virus specific antigen when analysed by indirect immunofluorescence microscopy. This persistently infected cell line resisted superinfection with either homologous or most heterologous flaviviruses. However, the yellow fever French neurotropic virus (YF FNV) multiplied in the persistently infected cells and evidence of dual infections in these cells was obtained using specific monoclonal antibodies in double labelling immunofluorescence tests. The relevance of these observations is discussed in the light of other evidence that tick-borne viruses can survive for long periods in wild animal species.
Animals↗
Influence of cellular functions on the evolution of persistent infections with Junin virus.
Vero cell cultures persistently infected with Junin virus and subjected to different cultural conditions were established. The production of infectious plaque-forming virus, ts mutants and interfering viral particles was determined at different times during 110 days after infection. Carrier cultures maintained in stationary conditions continuously released PFU while proliferating persistent cultures exhibited a cyclical pattern which tends to a rapid PFU disappearance. Concomitantly, in stationary cultures the production of interfering particles was delayed and was lower than in actively growing persistent cells. The metabolic state of the infected cells did not affect the release of ts mutants. The results suggest that a cellular function is involved on the regulation of Junin virus persistent infections.
Animals↗
Differential modulating effects of retinoic acid on interferon antiviral activity.
The effect of retinoic acid (RA) on the antiviral activity of interferons (IFNs) alpha and beta in the U937 and WISH cells was examined to ascertain whether or not RA could reduce the effectiveness of IFN-induced resistance to viral infection. Our results indicate that in the U937 cells, RA (0.1-1.0 microM) had neither enhancing nor suppressive effect on the antiviral activity of IFN-alpha or beta against the Semliki Forest virus (SFV). However, in the WISH cells, RA had different effects on IFNs alpha and beta. Thus, while RA (0.1-50 microM) invariably suppressed the activity of IFN-alpha, it enhanced the action of IFN-beta at low dose (0.1-1.0 microM) but became suppressive at higher concentrations (greater than or equal to 10 microM). Furthermore, higher antiviral activity was consistently obtained when RA (0.1-10 microM) was added prior to either IFN-alpha or IFN-beta comparing to cultures with IFN alone. In addition, direct correlation between antiviral activity and the amplitude of 2-5 oligoadenylate (A) synthetase activity was not observed. These results suggest that modulation of IFN antiviral activity by RA varies with different systems and is dependent on the sequence of treatment.
2',5'-Oligoadenylate Synthetase↗
Inhibition of porcine parvovirus replication by empty virus particles.
The influence of empty porcine parvovirus (PPV) particles on viral replication was examined in cell cultures and in swine. Following extensive purification, homogeneous preparations of full and empty PPV preparations were obtained and used for in vitro and in vivo analyses. In the first in vitro experiment, swine testes cells were infected with mixtures of various ratios of empty and full (E/F) particles. The production of both intracellular and extracellular virus was markedly inhibited in the presence of empty particles. This inhibition was dependent upon the concentration of empty particles present in the mixture. In the second in vitro study, various concentrations of empty particles were added prior to full virus infection. Again, marked inhibition of progeny virus production was evident and related to the concentrations of empty particles added. Based on the results of in vitro studies, the influence of empty particles on PPV infection in swine was tested by infecting mid-term and late-term gestation swine fetuses with various E/F particle ratios. Both mid-term and late-term fetuses exposed to 0:1, 1:1 and 5:1 E/F ratios displayed gross pathological evidence of PPV infection whereas fetuses exposed to E/F ratios of 30:1 or greater were grossly normal in appearance. However, fetuses infected with 30:1, 50:1 and 300:1 E/F ratios showed evidence of virus in their tissues by DNA hybridization. Regardless of the E/F ratios, late-term infected fetuses responded with high antibody titers ranging from 1024 to 4096. The results from these studies suggested that empty particles interfered with viral replication in both cell culture and in animals.
Animals↗
Effect of recombinant mouse interferon-beta on acute and latent herpes simplex infection in mice.
The antiviral effect of recombinant mouse interferon-beta (rMuIFN-beta) on herpes simplex virus type 1 (HSV-1) in experimentally infected mice was examined at several stages of infection as a model for the treatment of human HSV infection. Recombinant MuIFN-beta protected mice from lethal intraperitoneal challenge with virulent HSV-1 strains. The in vitro reactivation of HSV from latently infected trigeminal ganglia was also suppressed by treatment with rMuIFN-beta. Thus, rMuIFN-beta was effective against HSV-1 during acute infection and during in vitro reactivation of latent HSV. However, rMuIFN-beta was not effective in preventing the establishment of latent infection, or in eliminating a previously established latent infection.
Acute Disease↗
Suppression of humoral immune response against herpes simplex virus induced by defective strains, ts- and TK- mutants.
Suppression of humoral antibody formation against HSV is not only induced by replicating Herpes simplex virus type 2 (HSV-2) but also by the defective strain ANG and the deletion mutant 1301 of Herpes simplex virus type 1 (HSV-1). Moreover, ts-mutants A, H, K, S, 1201 and 1208 of HSV-1 as well as some ts-mutants of HSV-2 and "defective-interfering" particles of HSV-1 after high multiplicity of infection-passages induced suppression. Treatment of infected mice with ACG reduced antibody-formation but did not result in suppression. UV-irradiation of the antibody producing strain Len of HSV-1 strongly reduces antibody formation and induces suppression. Experiments using a series of intertypic recombinants showed the suppressing activity to be spread over the whole genome of HSV-2. It is concluded that suppression is induced by more than one region of the genome of HSV-2 and by incomplete replication of HSV-1 and 2.
Animals↗
Identification of a novel cell-type and context specific enhancer within the negative regulatory element of the human immunodeficiency virus type 1 long terminal repeat.
One segment of the negative regulatory region of the human immunodeficiency virus long terminal repeat (HIV-LTR), nucleotides -273 to -255, is homologous to positive response elements for interleukin-2 and glucocorticoids. We demonstrate that this sequence, referred to as purine-rich response element (PRRE), acts as a classic enhancer in the context of a heterologous promoter, but serves as a functional repressor in the intact provirus, binding (a) cellular factor(s). These data suggest that certain DNA response elements in the HIV LTR serve as negative regulators only in the context of the intact LTR, presumably through interactions with other transcriptional factors, a phenomenon that might be exploited to interfere with viral gene transcription.
Base Sequence↗
Two different strains of an alphaherpesvirus can establish latency in the same tissue of the host animal: evidence from bovine herpesvirus 1.
We inoculated plaque-purified bovine herpesvirus type 1 (BHV 1), strain K22, subtype BHV 1.2b, intravenously into susceptible cattle. Five months later, we reactivated latent virus with dexamethasone and then super-infected the same cattle intranasally and intravaginally with a different plaque-purified BHV 1, strain Cooper, subtype BHV 1.1. After a second dexamethasone treatment four months later, reactivated viruses were isolated and examined with restriction endonucleases. We showed that both virus subtypes were reactivated, proving that 2 different strains of an alphaherpesvirus can establish latency in the same tissue in the host animal.
Animals↗
Rubella virus RNA: effect of high multiplicity passage.
Evidence for the amplification of defective interfering particles of rubella virus after passage at high multiplicity has been obtained. The process is associated with the production of subgenomic rubella RNA species.
Animals↗
Host cell receptors for two strains of Sindbis virus.
Experiments were performed to determine whether neuronal cells have different numbers of receptors for a neurovirulent and an avirulent strain of the same virus and whether neurotropic strains of different viruses share the same cellular receptors. Attempts were also made to characterize the receptors for the two strains of Sindbis virus on viable cells by studying their enzyme sensitivity. The number of cellular receptors available for Sindbis virus attachment to several cell lines was determined by saturation studies using two virus strains differing in their pathogenicity for adult mice. Cultured neuronal cells had 1.3 x 10(6) receptors for a neurovirulent strain (SaAr86) and only 5 x 10(4) for the avirulent prototype strain (EgAr339) of Sindbis virus. A refractory Lepidopteran cell type possessed 1 x 10(5) surface receptors for the neurovirulent variant while the average number of receptors on five permissive cell types was 1.5 x 10(6). Cellular receptors for the two strains of Sindbis virus on rat glioma cells were found to be distinct. The cellular receptors for EgAr339 on viable mammalian cells were sensitive to proteolytic cleavage, while those on living mosquito cells were insensitive to proteases, phospholipases and neuraminidase. The receptors for the neurovirulent variant on three mammalian cell types were less sensitive to enzymatic inactivation than those for the avirulent counterpart. After cleavage, the receptors for EgAr339 reappeared rapidly at 37 degrees and 4 degrees C, apparently in the absence of cellular synthesis.
Aedes↗
Antiviral activity of virus-like particles from Lentinus edodes (Shiitake). Brief report.
Interferon (IF) induction and antiviral activity by purified spherical (S) or filamentous (F) virus-like particles and S-derived RNA was studied. A single administration of S particles prior to virus challenge reduced significantly the mortality of mice infected with western equine encephalitis (WEE) virus.
Agaricales↗
Influence of double infections on the induction of thymidine kinase by UV-irradiated herpes simplex virus types 1 and 2 and pseudorabies virus.
Simultaneous infection of primary rabbit kidney cells with HSV type 1 TK+ and a TK- strain results in a mutual influence of both viruses on the induction of thymidine kinase (TK). TK+ virus has an enhancing and TK- virus a depressing effect on TK induction by a superinfecting TK+ virus. The enzyme induction depends on the ratio of multiplicities of both viruses. The mutual influence on TK induction depends further on the time of addition of the superinfecting virus: the effect of the second virus can still be observed when given 6 hours after primary infection. Identical phenomena can be observed using combinations with HSV type 2 or Pseudorabies viruses. The ability of HSV to induce TK is progressively inactivated with increasing the time of UV-irradiation. The depressing effect of a TK- strain and the stimulating effect of a TK+ strain on superinfecting TK+ strains is UV-sensitive: after 6 minutes of UV-irradiation neither inhibition nor stimulation of TK induction by a superinfecting TK+ strain can be observed. Infection by long-term (20 minutes) UV-irradiated TK+ strains results in a depression of TK induction by a superinfecting TK+ virus. Long-term irradiation of the TK- virus does not show this effect. Cytosine-arabinoside has no effect on the mutual influence of TK induction by TK+ and TK-strains; the phenomenon of mutual depression therefore has to be considered an early process.
Cell-Free System↗
Binding of polyriboinosinic-polyribocytidylic acid with cultured cells.
Homogenates prepared from polyriboinosinic-polyribocytidylic acid copolymer [poly(rI) - poly(rC)]-treated cells exhibited antiviral activity in chick embryo, L and rabbit kidney cells. The antiviral activity in the homogenate co-sedimented with cellular membrane material and was shown to be poly(rI) - poly(rC) by a hybridization competition test with immobilized polyribocytidylic acid. The results indicate that poly(rI) - poly(rC) binds firmly to cellular membrane. These studies, however, could not differentiate between specific binding leading to the interferon induction and non-specific binding possibly unrelated to the induction of interferon.
Animals↗
Latent measles virus infection in Vero cells depending on a temperature-sensitive phenomenon.
A latent infection by measles virus in a line of Vero cells could be maintained only at 37 degrees C. The conditions of temperature nonpermissiveness were associated with some block in virus production and/or release and with the establishment of an autointerference phenomenon. Reduction of the incubation temperature to 33.5 degrees C induced a rather rapid transition from the latent to a lytical infection with a recue of virus. The rescued virus exhibited a restricted capacity to grow at 37 degrees C.
Animals↗
Interaction in replication between goose parvovirus strain B and duck plague herpesvirus.
The goose parvovirus strain B was found to replicate only in cells with DNA synthesis. Cells in the stationary phase of DNA synthesis or maintained under 2 mM thymidine (TdR) in excess were refractive to the parvovirus infection. However, stationary phase cells could be rendered to produce progeny paroviruses by herpesvirus superinfection. In reverse, the replication of the herpesvirus was significantly inhibited by parvovirus preinfection of cells.
Animals↗
Accidental persistent infection of cell lines by Newcastle disease virus, showing three unusual features--defective neuraminidase, temperature sensitivity and intranuclear inclusions.
A persistent, defective infection by an unknown strain of Newcastle disease virus (NDV) appeared accidentally in established lines of pig, ox and sheep kidney cells. Virus particles released from the persistently infected cells were not infectious and were deficient in neuraminidase activity. Synthesis of some of the virus-specified proteins in the persistently infected cells was temperature-sensitive. Co-cultivation of mixed populations of carrier cells and healthy chick embryo cells induced cell fusion with the formation of multinucleate heterokaryons and intra-nuclear inclusions. The development of inclusions in the chicken nuclei was not accompanied by 'rescue' of infectious NDV.
Animals↗