| how useful are serum and csf interferon levels as a rapid diagnostic aid in virus infections? | specimens from a total of 162 patients were studied prospectively using a rapid nucleic acid synthesis inhibition assay and a plaque-reduction assay to detect interferon levels in serum and cerebrospinal fluid. the specificity, consistency, and diagnostic applications of the rapid assay were evaluated by intensively investigating each patient for possible viral illness. forty-one percent of patients with proven acute virus infections (excluding those with acute hepatitis and infectious mononucle ... | 1985 | 2578554 |
| svlm21, a sindbis virus mutant resistant to methionine deprivation, encodes an altered methyltransferase. | the replication of sindbis virus (svstd) in cultured aedes albopictus mosquito cells is sensitive to methionine deprivation. we have suggested from earlier work that this sensitivity is primarily because of a decreased pool of s-adenosyl methionine (ado met) and the resultant failure to methylate the 5' cap of the viral mrnas. svlm21, a strain of sindbis virus derived in our laboratory from svstd by serial passage on mosquito cells maintained after infection in low concentrations of methionine, ... | 1989 | 2596021 |
| evidence for a t-cell related factor as the cause of demyelination in mice following semliki forest virus infection. | patchy demyelination throughout the central nervous system, including the optic nerve, is known to occur following infection with semliki forest virus (sfv) in swiss/a2g mice. an increase in the fast axonal transport of protein in optic nerves occurred before they showed signs of demyelination in swiss/a2g mice, heterozygous nude mice and nude mice reconstituted with t-cells. sfv infection, however, caused neither an increase in the fast axonal transport of protein, nor optic nerve demyelination ... | 1988 | 2458803 |
| a comparative study of entry modes into c6/36 cells by semliki forest and japanese encephalitis viruses. | the entry modes of semliki forest virus and japanese encephalitis virus into c6/36 cells were compared by electron microscopic observation. at physiological ph, the two viruses showed characteristically different entry modes. following attachment to the plasma membrane, many sf virions appeared within plasma membrane invaginations and cytoplasmic vesicles; on the other hand, je virions remained to be found exclusively at the cell surface, with no virions appearing within cytoplasmic vesicles. el ... | 1989 | 2596972 |
| spike--nucleocapsid interaction in semliki forest virus reconstructed using network antibodies. | using in vitro immunization, we have reconstructed three consecutive steps of an idiotype network to show that the nucleocapsid of semliki forest virus contains a specific 'receptor' for the cytoplasmic tail of the e2 spike glycoprotein. this interaction could be the basis for the highly selective inclusion of viral glycoproteins--and exclusion of host cell surface proteins--during virus budding. | 1988 | 2460771 |
| 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 ifn ... | 1989 | 2610595 |
| most alphaviruses share a conserved epitopic region on their nucleocapsid protein. | fourteen hybridoma cell lines secreting antibodies against the semliki forest virus nucleocapsid protein were established and employed for identification of conserved epitopes among 27 alphavirus types and subtypes. using an antibody capture test, the antibodies were found to cross-react to variable degree with alphaviruses belonging to the semliki forest, western encephalitis and eastern encephalitis complexes, as well as middelburg and ndumu. none of the antibodies reacted with either venezuel ... | 1989 | 2471798 |
| solubilization of protein fatty acyltransferase from placental membranes and cell-free acyl transfer on to exogenous and endogenous acceptors. | | 1989 | 2620775 |
| induction of salivation in biting midges and mosquitoes, and demonstration of virus in the saliva of infected insects. | culicoides biting midges and aedes aegypti (linnaeus) mosquitoes were induced to salivate by the topical application of pilocarpine, neostigmine, malathion and dimethoate; of these, malathion was the most effective. drops of saliva produced by virus-infected midges and mosquitoes were shown to contain virus. the method could be used to demonstrate transmission in insects infected with a variety of pathogens. | 1987 | 2856508 |
| common pathway for the induction of hexose transport by insulin and stress. | the effect of stress (heat shock, arsenite, or semliki forest virus [sfv] infection) on the induction of increased hexose transport has been compared with that of insulin. all four treatments increase the vmax for transport by bhk cells three- to five-fold, with little effect (less than 40% decrease) on km. hydrogen peroxide and phenylarsine oxide (pao) prevent the increase in hexose transport induced by stress treatments as effectively as they do that induced by insulin. pinocytosis is not affe ... | 1989 | 2645305 |
| semliki forest virus capsid protein acts as a pleiotropic regulator of host cellular protein synthesis. | the semliki forest virus capsid (c) protein was introduced into various target cells by electroporation-, liposome-, and erythrocyte-ghost-mediated delivery. data are presented which show that the incorporated c protein is biologically active and, at low concentrations (10(3) to 10(4) molecules per cell), markedly induces host cellular protein synthesis (average value, up to 90%). on the other hand, high concentrations (10(5) to 10(6) molecules per cell) led to a significant inhibition (average ... | 1989 | 2724418 |
| monoclonal antibodies that cross-react with the e1 glycoprotein of different alphavirus serogroups: characterization including passive protection in vivo. | a panel of four monoclonal antibodies (mab) were produced that cross-react with representatives of two different togavirus serogroups, namely sindbis (sin) and semliki forest (sf) viruses, by elisa and adcmc assays. three of these mab, igg2a and igg2b isotypes, passively protected c3h/hej mice against 10 and 100 ld50 of sf challenge and one, igm, did not protect against either challenge dose, or even at 1 ld50. all these mab were cross-reactive with the e1 glycoprotein of the viruses by immunobl ... | 1989 | 2773592 |
| differential phosphorylation of the nucleoprotein of influenza a viruses. | an analysis of the nucleoprotein (np) of 29 different influenza a viruses by phosphopeptide fingerprinting revealed three prototype patterns. the first, which was a complex pattern consisting of six to seven phosphopeptides, another which was relatively simple consisted of two or three phosphopeptides, and a third one which was complex but was missing the main phosphopeptide shared by the two other patterns. phosphoserine was the only labelled phosphamino acid detected. a tentative deduction of ... | 1989 | 2778438 |
| proteins are cointernalized with virion particles during early infection. | mammalian cells infected with enveloped or naked animal viruses become permeabilized to several proteins. the entry of alpha-sarcin, horseradish peroxidase, and luciferase is greatly increased during the early stages of viral infection. this process is promoted by uv-inactivated sfv, but not by heat-inactivated virions, suggesting that the process does not require viral gene expression. the entry of alpha-sarcin has been monitored both by its effects on protein synthesis and by indirect immunofl ... | 1987 | 2820142 |
| simian virus 40 infection is not mediated by lysosomal activation. | the uptake of simian virus 40 (sv40) virions to the nucleus, the site of viral replication, proceeds via engulfment at the cytoplasmic membrane and transport in monopinocytotic vesicles through the cytoplasm to the nuclear membrane. in the case of semliki forest virus and poliovirus which undergo primary endocytosis in a similar manner, neutralization of the acid ph in these vesicles abolishes viral infectivity. we have examined the effects of the lysosomotropic agents chloroquine and ammonium c ... | 1987 | 2821184 |
| the effect of gold sodium thiomalate in adult swiss/a2g mice infected with togaviruses and flaviviruses. | treatment of adult mice with gold sodium thiomalate made the normally non-lethal semliki forest virus and sindbis virus infections lethal and increased the virulence of langat and west nile viruses. these changes were associated with an enhanced virus invasion of the brain. depression of the humoral antibody response was not observed. | 1987 | 2822844 |
| persistence of encephalitogenic arboviruses in brain cell culture. brief report. | virus recovery from brain cultures of mice infected with either semliki forest and/or langat depended on the time interval between inoculation of either virus. mixed infections may alter the course of a disease. | 1987 | 2827614 |
| secondary structure and expression in vivo and in vitro of messenger rnas into which upstream aug codons have been inserted. | we wanted to discover whether the conformation of the mrna leader sequence is involved in translational fidelity. for this purpose we constructed several mutants of semliki forest virus 26s mrna and inserted aug codons into the leader sequence. we then analyzed the results of in vitro and in vivo translation of these mrnas, probed enzymatically the secondary structure and performed minimal energy folding of the transcripts. our results indicate that the position of a hairpin in the leader sequen ... | 1988 | 2831061 |
| role of interferon-gamma in t-cell responses to semliki forest virus-infected murine brain cells. | primary brain cell cultures prepared from newborn c3h mice were infected with semliki forest virus (sfv) or treated with a beta-propiolactone-inactivated preparation of sfv (bpl-sfv). the effects of recombinant interferon-gamma (ifn-gamma) treatment on sfv replication, sfv antigen display, major histocompatibility complex (mhc) class i and class ii antigen expression, susceptibility to lysis by sfv-specific cytotoxic t lymphocytes (ctl) and the ability to stimulate sfv-specific t lymphocytes to ... | 1988 | 2832313 |
| genome sequences of a mouse-avirulent and a mouse-virulent strain of ross river virus. | the nucleotide sequence of the genomic rna of a mouse-avirulent strain of ross river virus, rrv nb5092 (isolated in 1969), has been determined and the corresponding sequence for the prototype mouse-virulent strain, rrv t48 (isolated in 1959), has been completed. the rrv nb5092 genome is approximately 11,674 nucleotides in length, compared with 11,853 nucleotides for rrv t48. rrv nb5092 and rrv t48 have the same genome organization. for both viruses an untranslated region of 80 nucleotides at the ... | 1988 | 2833022 |
| effect of viral infection on experimental allergic encephalomyelitis in mice. | balb/c mice were irradiated with 350 r and injected with mouse spinal cord homogenate (msch) in complete freund's adjuvant. only 15-30% of these animals developed signs of experimental allergic encephalomyelitis (eae) at 21-28 days after inoculation. intraperitoneal infection with the non-lethal a7 strain of semliki forest virus (sfv) 7 days after sensitization reduced the mean appearance time of the eae symptoms to 14 days and the number of animals with clinical eae increased up to 70%. in cont ... | 1988 | 2833534 |
| nonstructural proteins nsp3 and nsp4 of ross river and o'nyong-nyong viruses: sequence and comparison with those of other alphaviruses. | we have sequenced the nsp3 and nsp4 region of two alphaviruses, ross river virus and o'nyong-nyong virus, in order to examine these viruses for the presence or absence of an opal termination codon present between nsp3 and nsp4 in many alphaviruses. we found that ross river virus possesses an in-phase opal termination codon between nsp3 and nsp4, whereas in o'nyong-nyong virus this termination codon is replaced by an arginine codon. previous studies have shown that two other alphaviruses, sindbis ... | 1988 | 2834873 |
| interferon-gamma is not an antiviral, but a growth-promoting factor for t lymphocytes. | the effects of interferon (ifn)-gamma or ifn-alpha/beta on virus yield, (2'-5')oligo(a) synthetase activation, h-2 antigen expression and proliferation of t lymphocytes have been investigated. under the culture conditions used, vesicular stomatitis virus or semliki forest virus replication in t cells was not impaired by the addition of ifn-gamma, whereas it was completely inhibited by the addition of ifn-alpha/beta. in contrast, b cell lines, macrophage-transformed cell lines and fibroblasts wer ... | 1988 | 2835246 |
| cns pathogenesis following a dual viral infection with semliki forest (alphavirus) and langat (flavivirus). | mice inoculated intraperitoneally with the alphavirus semliki forest were protected against a subsequent challenge with the flavivirus langat. the protection was seen as a reduction in the langat virus titres, mortality index and percentage deaths. the severity of the brain pathology was greater in the simultaneously infected mice, or when the time interval between administration of the viruses was 7 days, compared to that seen following a single infection of either semliki forest or langat viru ... | 1988 | 2837265 |
| the pathological effect on the central nervous system of mice following single and repeated infections of the demyelinating a7(74) strain of semliki forest virus. | the avirulent strain a7(74) of semliki forest virus was inoculated intraperitoneally into mice at weekly intervals for 7 weeks. pathological, virological and serological studies were carried out twice weekly, after each infecting dose. similar studies were performed on mice that had been given repeated inoculations at 2, 3 or 4 weekly intervals as were a group of control mice given a single dose of sfv. results showed grossly enhanced central nervous system lesions, in particular the perivascula ... | 1988 | 2841621 |
| impaired interleukin 1 and interleukin 2 production following in vitro abortive infection of murine spleen mononuclear cells by semliki forest virus. | the effect of semliki forest virus (sfv) infection of murine spleen mononuclear cells was investigated in vitro. a small percentage of spleen macrophages expressed viral antigens, but no infectious virus particles were released, indicating an abortive-type infection. wild-type sfv infected a higher percentage of macrophages than the attenuated, demyelinating mutant a7. the proliferation of spleen mononuclear cells under con a stimulation was inhibited by the viral infection. the supernatant (sn) ... | 1988 | 2844418 |
| redistribution of mr 75,000 plasma membrane protein, cytovillin, into newly formed microvilli in herpes simplex and semliki forest virus infected human embryonal fibroblasts. | we have previously purified an mr 75,000 protein from cultured human jeg-3 choriocarcinoma cells and showed that this protein is specifically confined to the cytoplasmic side of jeg-3 microvillar membranes. recently, the mr 75,000 protein, designated as cytovillin, was found to be expressed also in several other cultured human cell lines and strains, in which it was detected in microvillus-related structures. we now demonstrate the redistribution of cytovillin in herpes simplex type 1 (hsv-1) an ... | 1988 | 2846303 |
| replication of the genome of alphaviruses. | the genome of semliki forest virus (sfv) is 11,442 nucleotides with a 5' cap-structure and a 3' poly(a) tail of about 100 residues. the genome of the closely relate sindbis virus (sin) is slightly longer (11,703 nucleotides). the parental rna is first translated from the 5' two thirds to yield; nsp1, nsp2, nsp3 and nsp4, which are cleaved from a polyprotein of 2431 amino acids (sfv). the parental genome is copied to a full-length minus strand with poly(u) at the 5' end. the minus strand is used ... | 1987 | 2846593 |
| semliki forest virus (a7[74]) infection of adult mice induces an immune-mediated demyelinating encephalomyelitis. | | 1988 | 2849913 |
| dynamic changes in plasma membrane properties of semliki forest virus infected cells related to cell fusion. | the mechanism of the processes leading to membrane fusion is as yet unknown. in this report we demonstrate that changes in membrane potential and potassium fluxes correlate with semliki forest virus induced cell-cell fusion at mildly acidic ph. the changes observed occur only at ph's below 6.2 corresponding to values required to trigger the fusion process. a possible role of these alterations of the plasma membrane related to membrane fusion phenomena is discussed. | 1988 | 2850034 |
| enhancement of demyelination in the central nervous system of semliki forest virus infected mice after pretreatment with muramyl dipeptide. | semliki forest virus infections in mice produce an encephalitis with demyelination. if before giving the virus the mice are treated with muramyl dipeptide in freund's incomplete adjuvant, there is a significant increase in demyelination. if ovalbumin is added to the above and then followed after an interval by a second dose of ovalbumin and finally by the virus, the demyelination is further, but only marginally increased. the addition of ovalbumin without muramyl dipeptide in the schedule appear ... | 1988 | 2852310 |
| postinfection therapy of arbovirus infections in mice. | most antiviral agents are efficacious prophylactically in vivo, and a few are efficacious for postinfection (p.i.) therapy. to explore possibilities for p.i. therapy of encephalogenic banzi virus (bzv) and semliki forest virus infections in mice, we evaluated candidate antiviral therapies after development of the first clinical signs of infection. the earliest clinical indication of bzv viremia in mice is a rise in core body temperature beginning on day 3 p.i. bzv-infected mice showing elevated ... | 1989 | 2619276 |
| monensin-resistant mouse balb/3t3 cell mutant with aberrant penetration of vesicular stomatitis virus. | a mutant (mo-5) resistant to monensin (an ionophoric antibiotic) derived from the mouse balb/3t3 cell line, was a poor host for vesicular stomatitis virus (vsv) or semliki forest virus (sfv) multiplication. the yield of vsv particles in mo-5 is one 100-fold reduced as is vsv-dependent rna synthesis. in contrast to a ph-remedial mutant, the abortive production of infectious vsv particles in mo-5 cells was not restored by low ph treatment. the ph values in the endosome and the lysosome of mo-5 cel ... | 1985 | 2861207 |
| immunomodulation by bordetella pertussis: antiviral effects. | treatment of mice by intraperitoneal inoculation of pertussis vaccine or lipopolysaccharide extracted from b. pertussis will effect resistance to rabies virus, encephalomyocarditis virus, semliki forest virus, and herpes simplex virus. our previous observations indicated that treatment of c3h/hen (+/nu) and bdf1 mice with pertussis vaccine injected i.p. five days prior to a mouse adenovirus lethal dose i.p. challenge elicited resistance to clinical disease and death. susceptibility returned to a ... | 1985 | 2872109 |
| neurochemical changes in brains of mice infected with pichinde virus. | | 1986 | 2873503 |
| the use of sulfite to study the mechanism of membrane fusion induced by e1 of semliki forest virus. | in this study we have used 35s-labeled sulfite to modify the disulfide bonds of the proteins at the cell surface of semliki forest-infected aedes albopictus cells before and after low ph treatment. this reagent specifically cleaves disulfide bonds and concomitantly reacts with the newly formed cysteines, thereby labeling the respective protein. treatment of the infected cells with sulfite led to inhibition of the fusion activity only when applied after low ph exposure. these cells exhibited subs ... | 1989 | 2909989 |
| acidification of endosome subpopulations in wild-type chinese hamster ovary cells and temperature-sensitive acidification-defective mutants. | during endocytosis in chinese hamster ovary (cho) cells, semliki forest virus (sfv) passes through two distinct subpopulations of endosomes before reaching lysosomes. one subpopulation, defined by cell fractionation using free flow electrophoresis as "early endosomes," constitutes the major site of membrane and receptor recycling; while "late endosomes," an electrophoretically distinct endosome subpopulation, are involved in the delivery of endosomal content to lysosomes. in this paper, the ph-s ... | 1989 | 2925786 |
| morphological study on the entry of african swine fever virus into cells. | the early interactions between african swine fever virus (asfv) and monkey kidney cells in culture, and the effect of chloroquine were studied by electron microscopy. our results indicate that asfv uptake occurs by endocytosis: after attachment to the cell surface, the virions were seen in coated pits and were internalized by endocytosis in endosomes and finally in lysosomes. virions in coated vesicles were never seen. all these steps were completed in about 15 min. direct penetration of viruses ... | 1985 | 2937495 |
| semliki forest virus-specific non-structural protein nsp3 is a phosphoprotein. | antisera were raised in rabbits against fusion proteins consisting of beta-galactosidase and partial amino acid sequences of semliki forest virus (sfv)-specific non-structural proteins nsp1, nsp2, nsp3 and nsp4. the antisera were specific since each of them precipitated only one labelled protein of a size expected for nsp1, nsp2, nsp3 or nsp4 from lysates of [35s]methionine-labelled sfv-infected bhk-21 cells. the specific antisera also precipitated p220 (with sequences of nsp1, nsp2 and nsp3), p ... | 1988 | 2970523 |
| investigation of the role of glycans for the biological activity of semliki forest virus grown in aedes albopictus cells using inhibitors of asparagine-linked oligosaccharides trimming. | the effects of n-linked-oligosaccharide-processing inhibitors on the formation of semliki forest virus (sfv) in c6/36 aedes albopictus cells were investigated. the glycosidase inhibitors deoxynojirimycin, deoxymannojirimycin and swainsonine prevented the formation of endo-h resistant structures, but had little effect on virus formation and on the biological activities of the virus. tunicamycin greatly inhibited virus formation, but had little effect on cell-cell fusion from within and the cleava ... | 1988 | 2973779 |
| the effect of serum deprivation on the initiation of protein synthesis in mouse neuroblastoma cells. | growth of mouse neuroblastoma cells becomes stationary when cultured in serum-free medium. within 60 h, the protein-synthesizing capacity of the cells declines to 25% as compared to that of exponentially growing cells. the transitional activity of the crude ribosomal salt washes from serum-deprived and control cells was compared in in vitro protein-synthesizing ph 5 systems. it appears that the ribosomal salt wash from serum-deprived cells has significantly (70%) lost its ability to support the ... | 1985 | 2981551 |
| semliki forest virus infection of mice: a model for genetic and molecular analysis of viral pathogenicity. | | 1985 | 2982998 |
| different membrane anchors allow the semliki forest virus spike subunit e2 to reach the cell surface. | the semliki forest virus spike subunit e2, a membrane-spanning protein, was transported to the plasma membrane in bhk cells after its carboxy terminus, including the intramembranous and cytoplasmic portions, was replaced by respective fragments of either the vesicular stomatitis virus glycoprotein or the fowl plague virus hemagglutinin. the hybrid proteins were constructed by cdna fusion. upon a transient expression they could be localized at the cell surface by immunofluorescence with specific ... | 1985 | 2983116 |
| pattern and extent of demyelination in the optic nerves of mice infected with semliki forest virus and the possibility of axonal sprouting. | the optic nerves of all mice infected with semliki forest virus (sfv) showed patchy demyelination, although the extent of demyelination varied between animals. there was a significant increase in small diameter unmyelinated fibres in the optic nerves of sfv infected mice, paralleled by a loss of small myelinated fibres, suggesting that the smaller myelinated fibres may be more susceptible to virus-induced demyelination. the small unmyelinated fibres were more numerous in the peripheral region of ... | 1985 | 2983823 |
| mechanisms of monoclonal antibody-mediated protection against virulent semliki forest virus. | both neutralizing and nonneutralizing immunoglobulin g2a monoclonal antibodies (mas) directed against the e2 glycoprotein of semliki forest virus (sfv) protected mice prophylactically and therapeutically against virulent sfv infection. the neutralizing mas, however, conferred protection to mice at lower doses than did nonneutralizing mas. the antibody-dependent, complement-mediated cytolysis of sfv-infected l cells was effectuated by both kinds of antibodies, but again neutralizing mas were more ... | 1985 | 2985817 |
| expression of semliki forest virus capsid protein from sv40 recombinant virus. | here, the proteolytic processing of the semliki forest virus (sfv) capsid protein was studied in the absence of other viral functions. two different fragments of the sfv messenger cdna, coding for capsid protein and 174 and 38 extra amino acids from the envelope proteins, respectively, were cloned in the late region of the sv40 viral dna. cells infected with the sv40 recombinant virus stocks were analyzed for the production of sfv capsid mrna and polypeptide. immunofluorescence staining of the i ... | 1985 | 2989005 |
| establishment of cell lines persistently infected with foot-and-mouth disease virus. | cell lines persistently infected with foot-and-mouth disease virus (fmdv) have been established by growth of bhk-21 (c-13) or ibrs-2 (c-26) that survived standard cytolytic infections with fmdv. they maintain cytoplasmic fmdv rna sequences, as shown by dot blot hybridization tests, using cloned fmdv cdna as probes. cell line c1-bhk-rc1 was derived by infection of cloned bhk-21 c1 cells and plaque-purified fmdv c-s8 c1. indirect immunofluorescence assays indicated the presence of fmdv antigens. i ... | 1985 | 2990100 |
| endocytosis in saccharomyces cerevisiae: internalization of enveloped viruses into spheroplasts. | when vesicular stomatitis virus was incubated with saccharomyces cerevisiae spheroplasts at 37 degrees c, part of the virus was internalized by the spheroplasts as shown by the following criteria. (i) the spheroplast-associated virus was protected from proteinase k digestion, which releases surface-bound virus by degrading the envelope glycoproteins. (ii) the spheroplast-associated virus was resistant to mild triton x-100 treatment, which readily solubilizes the virus. the same results were obta ... | 1985 | 2992948 |
| cell surface influenza haemagglutinin can mediate infection by other animal viruses. | we have used filter-grown madin-darby canine kidney (mdck) cells to explore the mechanism by which influenza virus facilitates secondary virus infection. vesicular stomatitis virus (vsv) and semliki forest virus (sfv) infect only through the basolateral surface of these polarized epithelial cells and not through the apical surface. prior infection with influenza virus rendered the cell susceptible to infection by vsv or sfv through either surface. the presence of both a permissive and a restrict ... | 1985 | 2996880 |
| the pathogenicity of the a7, m9 and l10 strains of semliki forest virus for weanling mice and primary mouse brain cell cultures. | the multiplication of the m9, a7 and l10 strains of semliki forest virus (sfv), both in weanling mice and primary mouse brain cell cultures, was compared. following both intraperitoneal (i.p.) and intracerebral (i.c.) injection, the virulent l10 strain multiplied to higher titre in the mouse central nervous system (cns) than did the less virulent m9 and a7 strains, whereas m9 multiplied to higher titre than a7. by the i.c. route, all three virus strains multiplied to higher titre than following ... | 1985 | 2997371 |
| pyrimidinones. 1. 2-amino-5-halo-6-aryl-4(3h)-pyrimidinones. interferon-inducing antiviral agents. | interferon induction and antiviral activity was discovered with 2-amino-5-bromo-6-phenyl-4(3h)-pyrimidinone. an analogue study incorporating a series of 2-amino-5-substituted-6-arylpyrimidinones revealed that the most potent interferon inducers were mono- and difluorophenyl analogues. these same analogues were also potent antiviral agents against semliki forest virus and herpes simplex type 1. in addition the monomethoxyphenyl analogues were potent antiviral agents but weak interferon inducers. ... | 1985 | 2999405 |
| susceptibility of different leukemic cell lines to the anticellular and antiviral effects of interferons. | a total of 18 different types of human leukemic cell lines were tested for their susceptibility to the anticellular and antiviral effects of interferons (ifns) alpha, beta and gamma. in general, only the three myelogenous leukemic cell lines u937, kg-1 and hl-60 were found to be highly susceptible to the anticellular effect of the different ifns while cells of the other lineages were relatively resistant. in order to determine whether the cell lines were sensitive to the antiviral effects of ifn ... | 1985 | 2999858 |
| antiviral effect of 1-morpholinomethyl-tetrahydro-2(1h)-pyrimidinone (dd-13) in experimental alphaviral infections in white mice. | 1-morpholinomethyl-tetrahydro-2(1h)-pyrimidinone (dd-13), a selective inhibitor of the alphaviral reproduction in vitro, manifests a pronounced antiviral activity in experimental infections with semliki forest virus (sfv) and sindbis virus in white mice (intraperitoneally inoculated with 10-10 000 ld50). introduced subcutaneously in mice infected with sfv the compound was effective within the dose range of 4.7-300 mg/kg. the effective dose (ed)50 value of dd-13 is about 18.7 mg/kg and the maximu ... | 1985 | 3000394 |
| increased sugar transport in bhk cells infected with semliki forest virus or with herpes simplex virus. | infection of bhk cells by sfv increases the rate of uptake of [3h]meglc and of [3h]dglc at approximately 2 hours p.i. infection by hsv increases the uptake of [3h]meglc and [3h]dglc at approximately 10 hours p.i.; the increased uptake is prevented by acyclovir. it is concluded that an increased sugar uptake by infected cells reflects an increased rate of transport across the plasma membrane and is the result of cellular changes caused by virus infection. | 1986 | 3002302 |
| antiviral activity and mode of action of ribavirin 5'-sulfamate against semliki forest virus. | ribavirin 5'-sulfamate, a nucleotide analog, inhibited semliki forest virus cytopathology by 50% at 10 microm, whereas ribavirin was inactive at less than or equal to 1 mm. actinomycin d did not reverse (antagonize) the effect of ribavirin 5'-sulfamate against the virus. the compound inhibited amino acid incorporation into macromolecules of uninfected cells but had no appreciable effect on uridine incorporation. infected cells treated with actinomycin d and nucleotide analog were inhibited in am ... | 1988 | 2854956 |
| human natural killer cell lysis of virus-infected cells. relationship to expression of the transferrin receptor. | natural killer (nk) cells lyse tumor and virus-infected cells yet the nature of the target structure they recognize is unknown. a normal host cell glycoprotein, the transferrin receptor (tfr), has been proposed as a target structure on tumor cells. we therefore investigated whether changes in the number or physiological recycling of the tfr, consequent on virus infection, were related to the differential susceptibility of virus-infected cells to nk lysis. there was a direct correlation between t ... | 1986 | 3009202 |
| complex-specific immunoglobulin m antibody patterns in humans infected with alphaviruses. | sera from humans with serologically confirmed eastern equine encephalitis, western equine encephalitis, pogosta (ockelbo), mayaro, ross river, and chikungunya virus infections were tested by immunoglobulin m (igm) antibody capture enzyme immunoassay. diagnostically useful igm antibody titers were detected, and selected sera with high igm antibody titers were tested for igm antibody with nine heterologous alphaviruses. the results provide evidence for the complex specificity of igm antibody and i ... | 1986 | 3009526 |
| ross river virus mutant with a deletion in the e2 gene: properties of the virion, virus-specific macromolecule synthesis, and attenuation of virulence for mice. | a mutant of rrv t48 the prototype strain of ross river virus has been isolated with a 21-nucleotide deletion in the gene coding for the envelope glycoprotein e2. direct sequencing of the 26 s subgenomic rna, together with haeiii and taqi restriction digest analysis of cdna to rnas from cells infected with the mutant virus (rrv de2) and with rrv t48, were consistent with the deletion being the only major alteration in the mutant genome. the e2 protein of rrv de2 virions had a higher electrophoret ... | 1986 | 3010551 |
| persistence of virulent semliki forest virus in mouse brain following co-inoculation with defective interfering particles. | semliki forest virus (sfv) normally causes an acute lethal encephalitis in mice following intranasal inoculation. however, animals co-administered with 10 ld50 sfv and defective interfering (di) sfv survive the infection without clinical signs of disease. in this report we demonstrate the isolation of infectious virus from the brains of 12/169 protected mice up to 6.5 months post-infection. although, with one exception, mice were clinically normal, five of 12 of the sfv isolates were identical t ... | 1986 | 3011976 |
| 3-methylquercetin is a potent and selective inhibitor of poliovirus rna synthesis. | 3-methylquercetin (3mq) is a natural compound isolated from euphorbia grantii that selectively inhibits poliovirus replication, but has no effect on encephalomyocarditis virus. when the compound is present from the beginning of infection, the bulk of viral protein synthesis is prevented, but the shut-off of host protein synthesis still occurs. addition of 3mq 3 hr after infection has a slight effect on viral protein synthesis, suggesting that this compound blocks a step of viral replication diff ... | 1986 | 3012868 |
| the effect of overproduction of nonstructural proteins on alphavirus plus-strand and minus-strand rna synthesis. | we determined the effect of the overproduction of viral nonstructural proteins on alphavirus plus-strand and minus-strand rna synthesis. because alphavirus minus-strand synthesis ceases normally at 3 to 4 hr postinfection and requires continuous protein synthesis [d. l. sawicki and s. g. sawicki, j. virol. 34, 108-118 (1980); d. l. sawicki, s. g. sawicki, s. keranen, and l. kaariainen, j. virol. 39, 348-358 (1981a)], we determined if the cessation of minus-strand synthesis was the result of the ... | 1986 | 3014730 |
| early interactions between animal viruses and the host cell: relevance to viral vaccines. | viral recognition of specific receptors in the host cell plasma membrane is the first step in virus infection. attachment is followed by a redistribution or capping of virus particles on the cell surface which may play a role in the uptake process. certain viruses penetrate the plasma membrane directly but many, both enveloped and non-enveloped viruses, are endocytosed at coated pits and subsequently pass into endosomes. the low ph environment of the endosome facilitates passage of the viral gen ... | 1986 | 3014773 |
| the role of complement in monoclonal antibody-mediated protection against virulent semliki forest virus. | monoclonal antibodies (mas), specific for either the e1 or e2 glycoproteins of semliki forest virus (sfv), and belonging to various immunoglobulin subclasses (igm, igg2a, igg2b and igg3), effected lysis of sfv-infected l cells in co-operation with guinea-pig complement. in this antibody-dependent complement-mediated cytolysis (adcmc) test, igg1 mas were not effective although these antibodies recognize the viral antigens on the surface of sfv-infected l cells. the latter was shown with horseradi ... | 1986 | 3015781 |
| immunoelectron-microscopical labelling of glycolipids in the envelope of a demyelinating brain-derived rna virus (semliki forest) by anti-glycolipid sera. | immunoelectron-microscopical techniques using gold-labelled antibodies were used to localize the glycolipids ganglioside, glucocerebroside and galactocerebroside, and spike glycoprotein antigens, in the envelope of the rna virus semliki forest which had replicated in mouse brain cell cultures. the demonstration of host cell membrane glycolipid antigens in viruses is discussed in relation to the possibility of an autoimmune reaction to central nervous system cells. | 1986 | 3016202 |
| synergism between anti-rhinovirus antivirals: various human interferons and a number of synthetic compounds. | dcf (dichloroflavan), enviroxime, chalcone ro-09-0410 and huifn (human interferon)-alpha 2, huifn-beta, huifn-beta x 401 and huifn-gamma, showed antiviral activity in vitro against rv2 (rhinovirus type 2) and rv9. binary combinations of these drugs showed synergistic activity of which the combinations of huifn-gamma or huifn-alpha and enviroxime were of most interest. they were studied in more detail in tissue culture by virus yield experiments and in organ culture of human embryonic nasal epith ... | 1986 | 3017203 |
| reinitiation of translocation in the semliki forest virus structural polyprotein: identification of the signal for the e1 glycoprotein. | the biosynthesis of the semliki forest virus (sfv) structural proteins provides an interesting model system to study the reinitiation of translocation of membrane proteins into the endoplasmic reticulum membrane. the two transmembrane spike proteins, p62 and e1, are derived from a single polypeptide precursor. once the first protein, p62, has been anchored and its cytoplasmic tail has been synthesized, translocation must be reinitiated to account for the insertion of the e1 protein. we have used ... | 1986 | 3017702 |
| increased sensitivity of virus-infected cells to inhibitors of protein synthesis does not correlate with changes in plasma membrane permeability. | semliki forest virus-infected bhk cells or herpes simplex virus-infected vero cells were incubated with the protein synthesis inhibitors hygromycin b and gougerotin. infected cells take up no more [3h]hygromycin or [3h]gougerotin than do mock-infected cells, at a time p.i. at which either compound is more inhibitory to protein synthesis in infected, than in mock-infected cells. the concentrations of hygromycin and gougerotin required to inhibit protein synthesis in intact cells (irrespective of ... | 1986 | 3024398 |
| passive protection across subgroups of alphaviruses by hyperimmune non-cross-neutralizing anti-sindbis serum. | extended hyperimmunization of rabbits with sindbis (sin) or semliki forest (sf) viruses causes the production of antisera that are cross-reactive with virus-infected cells in antibody-dependent, complement-mediated cytotoxicity assays but that do not cross-neutralize viruses in vitro. c3h/hej mice given gamma globulin fractionated from the extended hyperimmune antiserum against sin, but not control sera, were protected from challenge by 100 ld50 of sf, a virus which is in a different subgroup th ... | 1987 | 3025890 |
| characterization of the fusion of enveloped viruses with the plasma membrane of saccharomyces cerevisiae spheroplasts. | vesicular stomatitis virus (vsv) was associated at low ph with saccharomyces cerevisiae spheroplasts. in the cold, the association was characterized as reversible binding to the spheroplast surface. at 37 degrees c, the association became irreversible due to fusion of the viral envelope with the yeast plasma membrane according to the following data. proteinase k digestion degraded the viral envelope glycoprotein g but left the internal n and m proteins of vsv intact and associated with the spher ... | 1987 | 3027101 |
| isolation and preliminary characterization of semliki forest virus mutants with altered pathogenicity for mouse embryos. | four temperature-sensitive (ts) mutants of the a7 strain of semliki forest virus (sfv) have been isolated. all mutants were defective in rna synthesis at the restrictive temperature (39 degrees c) compared to the permissive temperature (30 degrees c). since the body temperature of mice fluctuates between 37 degrees c and 39 degrees c, multiplication was also examined at 37 degrees c; only the multiplication of ts4 was restricted. after intraperitoneal infection of 8-day pregnant mice, the wild-t ... | 1987 | 3027238 |
| semliki forest virus induced, immune mediated demyelination: the effect of irradiation. | intraperitoneal infection with the avirulent a7(74) strain of the alphavirus semliki forest virus (sfv) induces an immune mediated demyelinating encephalomyelitis. the blood and brain virus titres, the serum antibody titres and the histopathological changes in the brains of normal mice and mice immunosuppressed with 5.0 or 8.0 gy total body irradiation (tbx) were determined. sfv infection of immunosuppressed mice resulted in persistently high blood and brain virus titres, neuronal pycnosis, para ... | 1987 | 3028463 |
| semliki forest virus-induced, immune-mediated demyelination: adoptive transfer studies and viral persistence in nude mice. | adoptive transfer experiments in athymic nude mice demonstrated that the demyelination seen in the central nervous system (cns) following semliki forest virus (sfv) infection was directly dependent upon sensitized t lymphocytes. antibodies generated during the infection did not seem to be involved in the demyelination, but thymus-dependent antibodies (igg) were responsible for the reduction of brain virus titres. in the absence of a t cell response and t cell-dependent antibody production, virus ... | 1987 | 3029281 |
| rapid analytical and preparative isolation of functional endosomes by free flow electrophoresis. | endosomes are prelysosomal organelles that serve as an intracellular site for the sorting, distribution, and processing of receptors, ligands, fluid phase components, and membrane proteins internalized by endocytosis. whereas the overall functions of endosomes are increasingly understood, little is known about endosome structure, composition, or biogenesis. in this paper, we describe a rapid procedure that permits analytical and preparative isolation of endosomes from a variety of tissue culture ... | 1987 | 3031085 |
| detection of flavivirus rna in infected cells using photobiotin-labelled hybridization probes. | ten plasmids containing viral cdna inserts of portions of the dengue virus type 2 (den-2) or kunjin virus (kun) genomes were biotinylated using photobiotin acetate and used as probes for the detection of flavivirus rna in infected vero cells. the viral cdna inserts ranged in length from 0.19 to 2.7 kilobase pairs, and represented segments of the flavivirus genome coding for structural and nonstructural proteins. in spot hybridization assays (hybridization at 60 degrees c) with rna extracted from ... | 1987 | 3031110 |
| cyclosporine enhances virally induced t-cell-mediated demyelination. the effect of cyclosporine on a demyelinating virus infection. | semliki forest virus infection of adult mice results in a demyelinating meningoencephalomyelitis. demyelination does not result from direct viral damage but from the activity of t lymphocytes. we have studied the effect of the immunosuppressant cyclosporine (cs) on the outcome of this infection. cs had no effect when given 5 days after the infection, and little effect when given 4 h after infection. when the cs was given 48 h before infection there was a prolongation of the blood and brain virus ... | 1987 | 3033157 |
| the effect of cycloleucine on sfv a7(74) infection in mice. | cycloleucine (cl), a non-metabolizable amino acid analogue, was found to reduce thymus and spleen weights in semliki forest virus (sfv) strain a7(74) infected and control mice. the maximum effects were seen when three daily doses of cl were given to mice 24 h after an sfv a7(74) infection. in these mice thymus atrophy led to abolition of thymus dependent immune responses and changes in the pathological features of the viral infection--the most striking feature being prevention of demyelination. ... | 1987 | 3034321 |
| enhanced retinal and optic nerve excitability associated with demyelination in mice infected with semliki forest virus. | the physiological effects of semliki forest virus (sfv) induced demyelination on the visual system of mice have been examined by recording electroretinograms (ergs) and the spike activity in the retinal ganglion cell axons in control and sfv-infected mice. the amplitudes of ergs evoked by a single flash in the dark-adapted eyes of the sfv infected mice were abnormally enhanced, whereas flicker ergs were slightly depressed. this hyperactivity was also seen in the ganglion cell axonal discharge. b ... | 1986 | 3002541 |
| stimulation of helper/delayed-type hypersensitivity t cells by flavivirus infection: determination by macrophage procoagulant assay. | west nile virus (wnv)-immune spleen cells produced an inducer of macrophage procoagulant activity (mpca) on restimulation with wnv in vitro. this response was specific for wnv and depended on the presence of thy 1+, l3t4+ and also ia+ cells but not lyt 2+ cells. it could be induced by culture with large amounts of non-infectious, u.v.-irradiated virus or with high doses of infectious virus. inoculation of mice with low titres of infectious, but not with u.v.-irradiated, virus primed for this in ... | 1986 | 3003235 |
| a neutralization-inhibition enzyme immunoassay for anti-idiotypic antibodies that block monoclonal antibodies neutralizing semliki forest virus. | in this paper we compare a solid-phase enzyme immunoassay (eia) with a neutralization-inhibition enzyme immunoassay (ni-eia) for the determination of anti-idiotypic antibodies against semliki forest virus (sfv)-neutralizing monoclonal antibodies (mas) um 5.1 (igg2a) and um 1.4 (igg2a). against these mas strong immune sera were induced in female balb/c mice by two subcutaneous injections, 3 weeks apart, with keyhole limpet hemocyanin coupled ma mixed with the saponin quil a. rabbit immune sera we ... | 1988 | 3058808 |
| immunological and cytological studies of autoimmune demyelination and multiple sclerosis. | the early history of experimental allergic encephalomyelitis is reviewed from the point of view of the characterization and recognition of myelin basic protein and the active agent in acid-fast bacilli, namely muramyl dipeptide. protocols effective in inducing demyelination are pinpointed. special attention is paid to the protocol which depends on pretreating guinea pigs with muramyl dipeptide and foreign protein followed by a second injection of foreign protein and then the animals are injected ... | 1988 | 3076485 |
| inhibition of endocytosis by anti-clathrin antibodies. | we examined the function of clathrin, a cytoplasmic protein associated with coated pits and vesicles, by introducing monoclonal antibodies into living cells and determining their effects on membrane transport. when anti-clathrin heavy chain antibodies were used, the following effects were observed: clathrin became aggregated in the cytoplasm, the number of coated pits on the plasma membrane was reduced, and adsorbtive endocytosis of semliki forest virus and fluid-phase endocytosis were decreased ... | 1987 | 3111717 |
| serological examinations for antibodies against west nile virus, semlikivirus and chikungunyavirus in laboratory mice, parasitized by nidicole fauna from swallow's nests. | experimental mice in swallow's (nmri) nests highly infested with swallow bugs (hirundo rustica) revealed antibodies against west nile virus, semliki virus and chikungunya virus. additional nidicole ectoparasites were not controlled and could also play a role in the occurrence of infection in experimental mice. swallows and sparrows (passer domesticus) additional nest inhabitants appear to be the ultimate link in this infection pathway as swallow bugs seldom migrate into dwellings to infest human ... | 1988 | 3139492 |
| inactivation of human immunodeficiency virus in serum specimens as a safety measure for diagnostic immunoassays. | since the human immunodeficiency virus (hiv) may be transmitted accidentally to laboratory personnel analyzing patient sera, the efficiency of a non-ionic detergent, triton x-100, in inactivation of hiv in human serum as a safety measure was studied. semliki forest virus, an enveloped toga virus, was used as a model virus to create optimal treatment conditions. in the presence of 50% serum, complete inactivation (i.e. no residual virus detected, greater than 7 log reduction of virus titre) was a ... | 1988 | 3141160 |
| potential contribution of mild pepsin treatment at ph4 to the viral safety of human immunoglobulin products. | different manufacturers use several different processes for the production of intravenous immunoglobulin. several manufacturers include a production step where the immunoglobulin is treated with low levels of pepsin at ph 4. a series of experiments were undertaken to assess whether or not ph 4/pepsin treatment could inactivate a range of test viruses. acid-labile viruses such as vaccinia, herpes simplex, mumps and semliki forest virus were found to be susceptible to ph 4/pepsin treatment whereas ... | 1988 | 3142151 |
| chemical identification of cysteine as palmitoylation site in a transmembrane protein (semliki forest virus e1). | the palmitoylation site of the membrane glycoprotein e1 of semliki forest virus (sfv) has been identified by chemical analysis of an acylpeptide. 3h-palmitoylated e1 isolated from sfv grown in baby hamster kidney cells was digested with chymotrypsin and the resulting peptides subjected to high performance liquid chromatography on a wide-pore column. the 3h-acylated peptide fraction peaked at above 60% 2-propanol in the eluent, indicating its hydrophobic character. polyacrylamide gel electrophore ... | 1988 | 3143715 |
| teratogenicity of the semliki forest virus mutant ts22 for the foetal mouse: induction of skeletal and skin defects. | the maximum proportion of skeletal and/or skin defects induced by the semliki forest virus (sfv) mutant ts22 in the 17-day-old foetal mouse occurred following infection of the mother at day 10 of pregnancy. the skeletal defects were detected using a combination of alcian blue staining for cartilage and alizarin red staining for bone. using immunogold-silver staining with anti-sfv igg and in situ hybridization with a cdna probe to sfv non-structural sequences, we have shown that mesenchymal cells ... | 1988 | 3183626 |
| infection of a human leukemia k-562 cell line with semliki forest virus. | infection of the human leukemia hematopoietic stem cell line, k-562, with semliki forest virus (sfv) can be characterized by three stages: (1) an early virus-proliferating stage lasting 1 to 4 days post-infection (pi) in which infectious virus is produced in high titers (10(3)pfu/cell) but in which there is minimal cytopathic effect. all cells appear viable by trypan blue dye exclusion, although they do not proliferate, and dna and cell protein synthesis decrease to less than 3% of uninfected co ... | 1988 | 3196168 |
| three-dimensional reconstruction from electron micrographs of disordered specimens. ii. implementation and results. | the computational procedures to implement the method described in the companion paper for three-dimensional reconstruction from projections of a disordered collection of single particles are presented. computer simulations are used to demonstrate the way the method functions, and practical aspects are discussed in detail. examples are given of how different symmetries can be exploited by imposing selection rules on the model equations. applications to negatively stained 50s ribosomes and to cryo ... | 1988 | 3212838 |
| processing the nonstructural polyproteins of sindbis virus: study of the kinetics in vivo by using monospecific antibodies. | plasmids were constructed which contained a large portion of each of the four nonstructural genes of sindbis virus fused to the n-terminal two-thirds of the trpe gene of escherichia coli. the large quantity of fusion protein induced from cells containing these plasmids was subsequently used as an antigen to generate polyclonal antisera in rabbits. each antiserum was specific for the corresponding nonstructural protein and allowed ready identification of each nonstructural protein and of precurso ... | 1988 | 3339717 |
| two distinct subpopulations of endosomes involved in membrane recycling and transport to lysosomes. | functionally distinct subpopulations of endosomes involved in targeting internalized material to specific intracellular destinations were resolved as two distinct peaks by free-flow electrophoresis. the less anodally shifted peak contained a population of early endosomes selectively labeled by brief exposures to endocytic tracers or by receptor-bound transferrin. late endosomes, labeled only after longer periods of internalization, migrated more toward the anode. while both fluid phase and certa ... | 1988 | 3345561 |
| exposure of semliki forest virus-infected baby hamster kidney cells to low ph leads to a proton influx and a rapid depletion of intracellular atp which in turn prevents cell-cell fusion. brief report. | the conditions needed to trigger semliki forest virus (sfv) induced cell-cell fusion from within (ffwi) of baby hamster kidney (bhk) cells differs from some other cells (e.g., aedes albopictus cells). in contrast to such cells it is mandatory for bhk cells to be brought back to a neutral ph after a short exposure to mildly acidic ph for fusion to occur. this phenomenon can be explained by a sudden drop of the intracellular ph observed after clamping the extracellular ph below 6.2--the ph require ... | 1988 | 3355372 |
| immunocytochemical evidence for semliki forest virus antigen persistence in mouse brain. | semliki forest virus (sfv) is neurotropic in mice. mature virulent virus (strain l10) can be identified within the cns by electron microscopy in adult mice. inspite of high virus titres, avirulent sfv a7(74) cannot be visualised in the brain of adult mice. immunocytochemical studies using monoclonal antibodies (mabs) to a7(74) e1 and e2 proteins and viral envelope glycolipids, showed viral e1 to be labelled in the cerebral capillaries, the e2 and the putative envelope glycolipids were labelled i ... | 1988 | 3385428 |
| an electron microscopical study of the replication of avirulent semliki forest virus in the retina of mice. | electron microscopical (em) studies were carried out on the retinas of 2-3-(baby), 12-, 14- and 21-28-day-old (adult) mice infected with avirulent (a774) semliki forest virus (sfv). virions (mature virus), spherules and advanced stages of virus replication, cytopathic vacuoles type ii (cpv ii), were seen in the retinal neurons of baby mice after intracerebral (i.c.) or intraperitoneal (i.p.) infection. some virions and spherules were also seen in the retinas of 12- and 14-day-old mice. virions a ... | 1988 | 3385430 |
| effect of dimethylsulfoxide (dmso) on virus replication and maturation. | at intermediate concentrations of dmso the yields of infectious virus and biologically active hemagglutinin and neuraminidase of an influenza a virus (fowl plague virus) and of reassortants therefrom are enhanced severalfold, even though viral protein synthesis is not significantly affected. a corresponding enhancing effect was also found with new castle disease and semliki forest viruses. at elevated concentrations of dmso virus yield decreases, and under these conditions the synthesis of the l ... | 1988 | 3390002 |
| astrocytes are not susceptible to lysis by natural killer cells. | a cell population from the central nervous system, of mainly astrocytes, was prepared and their susceptibility to natural killer cell lysis was compared to yac-1 cells and l929 cells. two populations of natural killer cells were used: the splenocytes of mice immunized with semliki forest virus 3 days previously and day 5 inflammatory cells from west nile virus-infected cba/h mouse brain. both cell populations showed high lytic activity on yac-1 cells and the effector cells possessed conventional ... | 1988 | 3397404 |
| overlapping open reading frames revealed by complete nucleotide sequencing of turnip yellow mosaic virus genomic rna. | the complete nucleotide sequence of turnip yellow mosaic virus (tymv) genomic rna has been determined on a set of overlapping cdna clones using a sequential sequencing strategy. the rna is 6318 nucleotides long, excluding the cap structure. the genome organization deduced from the sequence confirms previous results of in vitro translation. a novel open reading frame (orf) putatively encoding a pro-rich and very basic 69k (k = kilodalton) protein is detected at the 5' end of the genome. it is ini ... | 1988 | 3399388 |
| semliki forest virus particles containing only the e1 envelope glycoprotein are infectious and can induce cell-cell fusion. | hydrophobic interaction chromatography (phenyl- and octyl-sepharose) was performed with semliki forest virus to investigate the effect of low ph on its hydrophobicity. at neutral ph, the virus could be bound to the column and completely eluted by the detergent np-40. low ph treatment of virus prior to application to the column resulted in stronger binding as reflected by the increased amount of detergent necessary to totally elute the virus. if, however, the low ph treatment was done after bindi ... | 1988 | 3413984 |
| duck hepatitis virus: adaptation of a plaque assay to determine 50 per cent end points with duck sera. | an assay to determine 50 per cent neutralisation end points of duck anti-duck hepatitis virus sera was developed using a plaque assay to quantify residual virus. the optimal conditions were determined. ducklings produce a serological response within four days of vaccination and the response reaches a maximum within nine days. | 1987 | 3035661 |
| animal viruses promote the entry of polysaccharides with antiviral activity into cells. | charged polysaccharides such as heparin and carrageenan show potent antiviral activity in cultured cells. labelled [3h]heparin binds to several virion particles as evidenced by sepharose 6b chromatography. this binding is inhibited by carrageenan. the complex [3h]heparin-hsv1 virions is able to enter cells. thus, almost no entry of [3h]heparin is observed in control hela cells, whereas in the presence of hsv1 or poliovirus the amount of radioactivity internalized is enhanced. this internalizatio ... | 1987 | 3039997 |
| complete nucleotide sequence of the nonstructural protein genes of semliki forest virus. | the nucleotide sequence coding for the nonstructural proteins of semliki forest virus has been determined from cdna clones. the total length of this region is 7381 nucleotides, it contains an open reading frame starting at position 86 and ending at an uaa stop codon at position 7379-7381. this open reading frame codes for a 2431 amino acids long polyprotein, from which the individual nonstructural proteins are formed by proteolytic processing steps, so that nspl is 537, nsp2 798, nsp3 482 and ns ... | 1986 | 3488539 |