| electron microscopic observation of african swine fever virus development in vero cells. | african swine fever virus emerges from infected vero cells either from areas of smooth cell surface or from microvilli. the two patterns may occur at different sites on the same cell and are unique for this virus. the scanning electron micrographs supplement regular thin section views. | 1978 | 99488 |
| synthesis of dna in cells infected with african swine fever virus. | incorporation of 14c-thymidine by cells infected with african swine fever virus (asfv) occurs in the nucleus. part of this dna is transferred to the cytoplasm and becomes resistant to dnase. the nuclear fraction washed with triton x100 retained all labeled dna and was able to synthesize viral and cellular dna under in vitro conditions in the presence of the four deoxynucleoside triphosphates, mg+2, and sucrose. under similar conditions nuclei from uninfected cells synthesized very little dna. | 1979 | 117788 |
| african swine fever antibody detection in warthogs. | | 1979 | 122128 |
| enzyme-linked immunosorbent assay for the diagnosis of african swine fever. | | 1979 | 394467 |
| requirement of cell nucleus for african swine fever virus replication in vero cells. | the role of the cell nucleus in the development of african swine fever virus in vero cells has been studied. no viral growth could be detected in enucleated cells under conditions that allow normal development of sindbis virus. furthermore, african swine fever virus dna synthesis was inhibited more than 95% after infection of enucleated vero cells as compared with normal cells. | 1977 | 403300 |
| a solid-phase enzyme linked immunosorbent assay for the detection of african swine fever virus antigen and antibody. | a solid-phase enzyme-linked immunosorbent assay was developed to measure both african swine fever virus (asfv) antigen and antibody. experiments showed it to be reproducible and able to detect limiting antigen concentrations of 50--500 had50/ml. the assay was more sensitive than those used at present to detect asfv antibody and it is suggested that it might be of great diagnostic use in countries where african swine fever has recently appeared. | 1979 | 385771 |
| transmission studies with african swine fever virus. the early distribution of virus in pigs infected by airborne virus. | | 1977 | 908774 |
| additional characteristics of disease caused by the african swine fever viruses isolated from brazil and the dominican republic. | | 1979 | 298918 |
| some characteristics of african swine fever viruses isolated from brazil and the dominican republic. | | 1978 | 287093 |
| the growth of virulent african swine fever virus in pig monocytes and macrophages. | the replication of virulent african swine fever virus (asfv) in cultures of monocytes and macrophages derived from pig bone marrow (pbm) and pig leukocyte (pl) cells was investigated by light microscopy, immunofluorescence, haemadsorption and infective virus release. monocytes showed a high rate of infection and complete destruction within 2 to 3 days, whereas macrophages had only a very low level of infection and survived to form persistently infected cultures. these observations may explain th ... | 1978 | 340610 |
| african swine fever: microplaque assay by an immunoperoxidase method. | a microplaque assay for vero cell-adapted lisborn '60 strain of african swine fever virus (l'60-uncloned) and a large plaque-forming strain cloned from the l'60-uncloned strain was developed by an immunoperoxidase method. the immunoperoxidase method can be used to stain microplaques of 3 days after inoculation, whereas the conventional plaque assay requires 5 to 7 days to develop visible plaques. a linear relationship between viral concentration in the inoculum and plaque numbers was observed. v ... | 1978 | 345892 |
| the basis of arbovirus classification. | the biologically defined set of arboviruses contains well over 300 separate viruses which have been subdivided into some 40 serological groups on the basis of antigenic cross-reactivity. more than three quarters of all arboviruses can now bw placed into one of the following five major taxonomic genera based upon the fundamental properties of the virion: alphavirus, flavivirus, orbivirus, rhadovirus, bunyavirus. there are 20 alphaviruses, representing serological group a, and 57 flaviviruses in s ... | 1975 | 1207193 |
| effect of disodium phosphonoacetate and iododeoxyuridine on the multiplication of african swine fever virus in vitro. | disodium phosphonoacetate (paa) was found to inhibit the replication of african swine fever virus (asfv). the action of this compound has been compared with the inhibitory capacity of iododeoxyuridine (idu) upon asfv growing in vero cells. the study was done by the immunofluorescence technique in order to detect formations of cytoplasmic virus antigens and inclusion bodies; both were found to be inhibited by idu and paa. at 100 microgram/ml, idu blocked completely the multiplication of asfv and ... | 1979 | 378573 |
| glutaraldehyde inactivation of exotic animal viruses in swine heart tissue. | glutaraldehyde, 0.2%, in a 1:100 (wt/vol) ratio, inactivated four animal viruses (foot-and-mouth disease, swine vesicular disease, african swine fever, hog cholera) in swine heart tissues during 11-day exposures at 22 to 26 degrees c. | 1979 | 225989 |
| transmission studies with african swine fever virus. infections of pigs by airborne virus. | | 1977 | 908773 |
| sensitivity of macrophages from different species to african swine fever (asf) virus. | the swine white blood cells sensitive to african swine fever (asf) virus are monocytes differentiated in vitro to macrophages. these cells have been characterized by their morphology, phagocytic capacity and the presence of receptors for swine immunoglobulin g in their membranes. asf virus does not produce any detectable effect on macrophages from humans, rabbits, guinea pigs, hamsters or rats, whereas asf virus-infected chicken macrophages show an enhancement of cellular dna synthesis and an in ... | 1977 | 856945 |
| cellular immunity demonstrated in pigs infected with african swine fever virus. | twenty-two pigs infected with african swine fever virus (asfv) were used to demonstrate delayed hypersensitivity (dh) in vitro by the leukocyte migration-inhibition test. the results indicated that asfv-infected pigs developed dh against asfv antigen (asf antigen) as early as 20 days after inoculation, and the presence of viremia did not interfere with the leukocyte migration-inhibition test. three asfv-infected pigs that were also sensitized to mycobacterium developed dh against both asf antige ... | 1977 | 835865 |
| stability of three animal viruses in thyroid tissue from infected swine. | | 1979 | 224564 |
| design and construction of an apparatus for the growth of micro cell cultures on standard glass microscope slides and its application for screening large numbers of sera by the indirect fluorescent antibody technique. | a simple stainless-steel apparatus was designed to contain standard microscope slides on which were grown micro cell cultures in the form of 16 individual monolayers per slide. the application of this apparatus for the screening of serum samples by fluorescent antibody techniques is described. | 1975 | 170316 |
| negative staining of a non-haemadsorbing strain of african swine fever virus. | since the application of negative staining, preceded by fixation, prevents the disruption and distortion of the capsid of the african swine fever virus, improved contrast and evaluation of the appearance and size of virus particles in the electron microscope is possible and, in addition, the icosahedral shape of the virus is demonstrable. the mature virus particle contains at least 2 capsid layers and an outer envelope. | 1977 | 78480 |
| isolation and properties of the dna of african swine fever (asf) virus. | african swine fever (asf) virus was grown either in swine macrophages or in vero cells and purified free of cell dna. virus dna was isolated from virions as a molecule with a sedimentation coefficient of 60s and a contour of 58 +/- 3 mum. .these two values give a mol. wt. of 102 +/- 5 x 10(6) and 107 +/- 5 x 10(6), respectively, for the genome of asf virus. denatured dna fragments from asf virus reassociate with a c0t1/2 value of 0-60 +/- 0-05 ms, which compared with the corresponding value for ... | 1976 | 823295 |
| titration of african swine fever (asf) virus. | a haemadsorption microtest for african swine fever (asf) virus is described. this assay is as sensitive and its response is faster than the conventional assay which uses buffy coat cultures in leighton tubes. the method can also process a larger number of samples by using smaller amounts of swine blood and laboratory space. a plaque assay for asf virus adapted to grow in vero cells gives a titre similar to that obtained using the haemadsorption microtest. in both the micromethod and the plaque a ... | 1976 | 823294 |
| inhibition of african swine fever (asf virus replication by phosphonoacetic acid. | phosphonoacetic acid (paa) inhibits the multiplication of african swine fever (asf) virus in vero cells. the observed inhibition of the in vivo dna synthesis could be related to the in vitro inhibition of a virus-induced dna polymerase activity present in cytoplasmic extracts from infected vero cells. | 1978 | 650176 |
| the replication of african swine fever virus in pig endothelial cells. | | 1978 | 566606 |
| african swine fever: pathogenicity and immunogenicity of two non-haemadsorbing viruses. | the virulence of 2 non-haemadsorbing african swine fever virus isolates were compared with 2 haemodsorbing viruses. while 3 of these isolates usually produced acute death in pigs, 1 non-haemadsorbing virus caused either a fatal infection with an extended course, or few or no obvious signs of infection. pigs that survived infection with the latter virus were resistant to the lethal effects of the other 3 strains as well as to a pool of 7 isolates made from ornithodorus porcinus porcinus (senus wa ... | 1979 | 551362 |
| african swine fever virus replication in porcine lymphocytes. | purified preparation of porcine lymphocytes were infected with three isolates of virulent african swine fever virus (asfv). electron microscopy showed the presence of small numbers of mature virus particles in degenerating cells. the titres of infective virus released were low and reached a maximum by 24 h after infection. | 1977 | 562925 |
| residual viruses in pork products. | partly cooked canned hams and dried pepperoni and salami sausages were prepared from the carcasses of pigs infected with african swine fever virus and pigs infected with hog cholera virus. virus was not recovered from the partly cooked canned hams; however, virus was recovered in the hams before heating in both instances. both african swine fever virus and hog cholera virus were recovered from the dried salami and pepperoni sausages, but not after the required curing period. | 1978 | 564162 |
| the association of african swine fever virus with blood components of infected pigs. | the distribution of african swine fever virus (asfv) in whole blood, plasma, red blood cells (rbc) and white blood cell (wbc) sub-populations was determined in pigs infected with virulent virus. changes in the rbc and wbc populations were also examined. total wbc counts decreased and rbc numbers remained unchanged during the course of the disease. the number of circulating lymphocytes decreased whilst neutrophil numbers increased owing to the replacement of mature forms by juveniles. virus was p ... | 1977 | 563710 |
| the replication of virulent and attenuated strains of african swine fever virus in porcine macrophages. | the replication of virulent and attenuated strains of african swine fever virus (asfv) was studied in pure cultures of swine macrophages. to ensure complete destruction of the macrophage monolayers about 50--100 times more virulent asfv was needed than attenuated virus although both isolates could be used to establish persistently infected cultures. interferon did not appear to influence virus yields from such cultures. fluorescent and electron microscopy studies of infected macrophages suggeste ... | 1979 | 496644 |
| purification and physicochemical characteristics of african swine fever virus. | methods for the purification of african swine fever virus (asfv) and its dissection into two fractions are described. the difficulties which have been encountered previously in attempts to purify the virus, namely contamination with large amounts of cellular constituents and aggregation of the virus particles, have been overcome by treatment with tween 80 and by the use of 1 m-nacl in the sucrose gradients. five major polypeptides, mol. wt. 10(3) x 125 (vp1), 76 (vp2), 50 (vp3), 44 (vp4) and 39 ... | 1976 | 965949 |
| cross-links in african swine fever virus dna. | african swine fever virus dna sediments in neutral sucrose density gradients as a single component with a sedimentation coefficient of 60s. in alkaline sucrose density gradients, this material shows two components with sedimentation coefficients of 85s and 95s, respectively. the sedimentation rate value of alkali-denatured virus dna in neutral sucrose density gradients and the renaturation velocity of denatured dna show that is reassociated much faster than expected from its genetic complexity. ... | 1979 | 513189 |
| solid-phase radioimmunoassay techniques for the detection of african swine fever antigen and antibody. | a solid phase radioimmunoassay (ria) has been successfully developed to measure both african swine fever virus (asfv) antigen and antibody. studies show that the assay is reproducible and will detect limiting antigen concentrations equivalent to 50--500 had50/ml. both direct and indirect antibody ria have been developed and have proved to be approximately 100 times fore sensitive than the complement fixation test at present available and 1000 times more sensitive than the immuno-electro-osmophor ... | 1979 | 489964 |
| crossed immunoelectrophoretic characterization of virus-specified antigens in cells infected with african swine fever (asf) virus. | | 1977 | 407329 |
| isolation and segregation of non-haemadsorbing strains of african swine fever virus. | | 1976 | 1014300 |
| plaque formation by african swine fever virus in chick embryo fibroblasts in the absence of co2 atmosphere. | a plaque assay method using asfv previously adapted to growth in chick embryo fibroblasts is described. chick embryo fibroblast monolayers under bactoagar or methylcellulose have been employed using cysteine, arginine, deae-dextran and hepes as additives. plaque production was optimal under methylcellulose. hepes rendered the plaques more clear when used with the overlay. arginine enhances plaque formation with bactoagar, and deae-dextran doubles the plaque size. the growth curve of asfv in chic ... | 1976 | 1033755 |
| [serological identification and behavior of the highly virulent swine fever virus in immunoelectrophoresis]. | | 1975 | 1136613 |
| the use of a microtitration technique for the routine assay of african swine fever virus. brief report. | | 1975 | 1168046 |
| ultrastructural study of african swine fever virus replication in cultures of swine bone marrow cells. | cultures from pig bone marrow cells were infected with asfv and the replication cycle was studied. in the cytoplasmic replication areas there are a differentiation of membrane segments. some of them are polygonal, which give rise to virus particles. an over production of viral coded materials, including non-polygonal membranes seems to be an important feature of the replicative cycle of asfv in this cell system. viruses are released enveloped with a cellular membrane. paracrystalline arrays of v ... | 1975 | 1239040 |
| [the functional role of the glycosylation of viral components]. | an inhibitory analysis of the role of glycosylation and glycoproteins in the manifestations of the most important properties of african swine virus was carried out using a set of strains and variants with contrasting characteristics. glycoproteins were shown to realize some virus functions such as virulence and its variability, intracellular transport and exocytosis of virions, hemadsorption, but not immunological recognition of the infected cells by cytotoxic t-lymphocytes. | 1992 | 1290229 |
| identification of an african swine fever virus gene with similarity to a myeloid differentiation primary response gene and a neurovirulence-associated gene of herpes simplex virus. | here we describe an open reading frame (lmw23-nl) in the african swine fever virus genome that possesses striking similarity to a murine myeloid differentiation primary response gene (myd116) and the neurovirulence-associated gene (icp34.5) of herpes simplex virus. in all three proteins, a centrally located acidic region precedes a highly conserved, hydrophilic 56-amino-acid domain located at the carboxy terminus. lmw23-nl predicts a highly basic protein of 184 amino acids with an estimated mole ... | 1992 | 1323711 |
| analysis of t lymphocyte subsets proliferating in response to infective and uv-inactivated african swine fever viruses. | the proliferative response to infective and uv-inactivated african swine fever virus was analyzed in cells from pigs surviving an experimental infection with attenuated virus. all the pigs showed strong dose-dependent proliferative responses to both infective and uv-inactivated virus. this response was also observed when nitrocellulose-bound solubilized virus proteins were used in the assay. heterologous isolates also induced proliferation, however it was significantly lower than that induced by ... | 1992 | 1362304 |
| genes homologous to ubiquitin-conjugating proteins and eukaryotic transcription factor sii in african swine fever virus. | the nucleotide sequence of the 6004-bp ecori i fragment of african swine fever virus dna has been determined. translation of the sequence revealed eight closely spaced open reading frames (orfs), three of them reading rightward and five leftward. northern blot hybridization analysis indicated that orfs i73r and i78r were transcribed early in infection, whereas orfs i177l, i196l, and i329l were expressed at late times. transcripts for orfs i215l, i226r, and i243l were detected at low levels in ea ... | 1992 | 1309282 |
| evolution of thymidine and thymidylate kinases: the possibility of independent capture of tk genes by different groups of viruses. | phylogenetic analysis of viral and cellular thymidine and thymidylate kinases was performed using computer-assisted methods. multiple alignments and tentative phylogenetic trees were generated for the two families of these enzymes, which include a) thymidine kinases (tk) of mammals, poxviruses, african swine fever virus, e. coli, and bacteriophage t4; and b) thymidylate kinases (thyk) of yeast and poxviruses and distantly related herpesvirus proteins with both enzymatic activities. analysis of t ... | 1992 | 1317076 |
| african swine fever virus infection in the iberian soft tick, ornithodoros (pavlovskyella) marocanus (acari: argasidae). | one thousand six hundred ornithodoros (pavlovskyella) marocanus velu larvae were fed on a pig infected with african swine fever virus (titer: 10(7.4) had50/ml), and 1,600 larvae were fed on an uninfected pig. ticks in each group were compared for mortality rates, mean time to death for ticks that died, mean time from feeding to either molting or eclosion, percentage of ticks that eclosed or molted, and the number of blood meals per nymph or instar. cumulative virus-induced mortality for all imma ... | 1992 | 1404269 |
| analysis of the specificity of the salivary antigens of ornithodoros erraticus for the purpose of serological detection of swine farms harbouring the parasite. | in spain, considerable efforts are currently being devoted to the eradication of ornithodoros erraticus from the swine farms harbouring this parasite, the european vector of african swine fever (asf). however, to do so, a preliminary requirement is to determine on which farms it is present. of all possible methods for discovering this, the only one feasible for large scale application is the serological detection of swine bearing anti-o. erraticus antibodies. to apply serology it was necessary t ... | 1992 | 1373884 |
| flow cytometric analysis of african swine fever virus-induced plasma membrane proteins and their humoral immune response in infected pigs. | african swine fever (asf) virus-induced plasma membrane proteins may contribute to the protective immune response against the disease since they can be involved in the antibody-mediated lysis of infected cells. in this study we describe the regulation of asf virus-induced plasma membrane protein expression and its antibody induction in pigs after viral infection by flow cytometric analysis. more than 80% of infected cells contained viral antigens on the surface membranes at 6 hr postinfection (h ... | 1992 | 1376539 |
| african swine fever virus encodes a gene with extensive homology to type ii dna topoisomerases. | nucleotide sequencing of a virulent african swine fever virus (asfv) isolate (malawi lil20/1) identified an open reading frame of 1191 amino acid residues encoding a protein of 134.9 kda. this gene mapped to the sali i and j restriction endonuclease fragments of the asfv genome. the predicted polypeptide was found to share 21.1% identity over a 1077 amino acid region with the human type ii dna topoisomerase. the sequence is compared to other type ii dna topoisomerases and the possible roles in a ... | 1992 | 1335084 |
| african swine fever virus-induced dna polymerase is resistant to aphidicolin. | african swine fever virus (asfv) induces the synthesis of a virus-specific dna polymerase, which is inhibited by phosphonoacetic acid and cytosine arabinoside. in contrast to all other alpha-like dna polymerases of dna viruses, asfv-specific dna polymerase is resistant to aphidicolin. concentrations of the drug as high as 160 microm had no effect on virus production or plaquing efficiency. the resistance of asfv dna polymerase to aphidicolin was confirmed by analyzing the effect of the drug on v ... | 1992 | 1413523 |
| distribution of asfv antigens in pig tissues experimentally infected with two different spanish virus isolates. | lymph nodes, spleen, liver, lung and kidney obtained from pigs experimentally infected with two african swine fever virus (asfv) isolates of differing virulence were fixed by perfusion with glutaraldehyde and embedded in paraffin. an immunoperoxidase technique using a polyclonal anti-asfv serum was performed on tissue sections in order to detect asfv antigen. the distribution of asfv antigen in such infected organs is shown and the differences between both infections compared and discussed. mono ... | 1992 | 1414093 |
| transcriptional analysis of multigene family 110 of african swine fever virus. | a transcriptional analysis of the 3.2-kb region of the african swine fever virus genome containing the five members of the multigene family 110 is presented. the mrnas corresponding to the genes studied have short leader sequences with no intervening aug codons before the translational start site, and their 3' ends map within a conserved sequence motif formed by a stretch of seven or more consecutive thymidylate residues. the possible role of this sequence as a signal for the 3'-end formation of ... | 1992 | 1404609 |
| [immune reactions to the african swine fever virus]. | host immune reactions to african swine fever virus variants differing in their virulence were studied comparatively. their obvious variabilities in antibody induction to some polypeptides active in antibody-dependent cell cytotoxicity and cytotoxic t-lymphocytes were demonstrated. t-helpers of immune pig splenocytes were found to recognize the cells infected with avirulent but not virulent virus variants. the described differences were not connected with the changes in sla-1 antigen expression i ... | 1992 | 1441445 |
| molecular characterisation of a dna ligase gene of the extremely thermophilic archaeon desulfurolobus ambivalens shows close phylogenetic relationship to eukaryotic ligases. | a 3382 bp fragment containing a gene for a dna ligase from the extremely thermophilic, acidophilic, and facultatively anaerobic archaeon (archaebacterium) desulfurolobus ambivalens was cloned and sequenced. the deduced amino acid sequence (600 amino acids, 67619 molecular weight) showed 30-34% sequence identity with the atp-dependent eucaryal (eukaryotic) dna ligases of schizosaccharomyces pombe, saccharomyces cerevisiae, the human dna ligase i, and with the vaccinia dna ligase. distant similari ... | 1992 | 1437556 |
| african swine fever virus infection in the soft tick, ornithodoros (alectorobius) puertoricensis (acari: argasidae). | in total, 1,186 second instar ornithodoros (alectorobius) puertoricensis fox second instars were fed on a pig when it had a viremia of 10(5.2) hemadsorption units (had50/ml) and 420 second-instar o. puertoricensis were fed on an uninfected pig. subsequent blood meals for ticks in both groups were from uninfected pigs. the effects of african swine fever virus (asfv) infection on o. puertoricensis populations were evaluated for the following parameters: mortality; mean time to death; percentage mo ... | 1992 | 1460641 |
| [polypeptides p14 and p31 of the african swine fever virus--early proteins located on the membrane of the infected cell]. | african swine fever virus polypeptides p14 and p31 are synthesized in the presence of phosphonacetic acid which inhibits viral dna replication, and therefore they are early viral proteins. these polypeptides were found to be localized on plasma membranes by immunofluorescence with monospecific antisera and monoclonal antibodies and by selective solubilization of infected cells. the p14-specific antibodies mediate complement-dependent cytolysis and antibody-dependent cytotoxicity of the cells inf ... | 1992 | 1441444 |
| localization of african swine fever viral antigen, swine igm, igg and c1q in lung and liver tissues of experimentally infected pigs. | an immunohistological study was carried out on lungs and livers of pigs experimentally infected with two different african swine fever virus (asfv) isolates. asfv antigen, swine immunoglobulins (igm and igg) and (clq) complement were demonstrated in both organs at different stages of infection. the asfv antigen was mainly found in mononuclear phagocytic system (mps) cells. immunoglobulins and complement were observed in plasma, infected and non-infected phagocytic cells and cell debris. these fi ... | 1992 | 1430349 |
| experimental transmission of african swine fever virus by the soft tick ornithodoros (pavlovskyella) marocanus (acari: ixodoidea: argasidae). | a total of 1,600 ornithodoros (pavlovskyella) marcocanus larvae were fed on a pig with a viremia of 10(7.4) had50/ml of african swine fever virus (asfv). infected larvae were sampled daily for 15 d, and nymphs were sampled at least once per instar until they became adults. initial titers of 10(4.48) had50 per larva declined to 10(4.04) within 2 d. larval titers reached a maximum of 10(6.0) had50 per larva 10 d after the infective blood meal. nymphs of each instar were fed on a susceptible pig an ... | 1992 | 1495075 |
| approaches to the identification of non-essential genes of african swine fever virus. | it is poorly understood why vaccines could not be developed for the control and prevention of african swine fever (asf) virus infection. the aim of our study was to identify genes non-essential for asf virus replication because there were indications that certain viral gene products, which apparently are non-essential for viral replication, conferred protection from death due to asf. a cosmid library representing the genome of asf virus strain france 64 was established and characterized. then, i ... | 1992 | 1481351 |
| analyses of the primary in vitro responsiveness of non-immune porcine peripheral blood mononuclear cells with reference to immunization by african swine fever virus antigen and treatment with leucine methyl ester. | peripheral blood mononuclear cells (pbmc) from non-immune pigs were immunized in vitro using african swine fever (asf) virus antigen with concomitant mitogenic stimulations known to have varying effects on b and t lymphocyte activity. none of these conditions, including those previously reported as being successful for the in vitro immunization of non-immune porcine pbmc with asf virus antigen, supported the induction of specific antibody. due to the reports on in vitro immunization of human pbm ... | 1992 | 1487303 |
| does hiv cause aids? a review. | it would require a detailed knowledge of virology, molecular biology, epidemiology, clinical medicine and politics, to appropriately compare and contrast the hypotheses on the causes of aids. the purpose of this review was not to do that, but to inform colleagues that alternative etiologies for aids have been considered. no doubt, this healthy questioning will continue until it has been demonstrated--via controlled studies of high-risk groups (both hiv positive and negative), matched for all oth ... | 1992 | 1458356 |
| a sensitive dot immunobinding assay for serodiagnosis of african swine fever virus with application in field conditions. | the present work describes a simple dot immunobinding assay (dia) for african swine fever virus (asfv) antibody detection that can be used under field conditions. the assay uses nitrocellulose strips dotted with a cytoplasmic soluble antigen (cs-p) of asfv. the nitrocellulose strips are adhered to a plastic handle. the test serum samples react with the cs-p, and antibodies are detected using a protein a-peroxidase conjugate. both incubations are carried out at 20 c. the efficacy of the dia as a ... | 1992 | 1515486 |
| a ubiquitin conjugating enzyme encoded by african swine fever virus. | the post-translational modification of proteins by covalent attachment of ubiquitin occurs in all eukaryotes by a multi-step process. a family of e2 or ubiquitin conjugating (ubc) enzymes catalyse one step of this process and these have been implicated in several diverse regulatory functions. we report here the sequence of a gene encoded by african swine fever virus (asfv) which has high homology with ubc enzymes. this asfv encoded enzyme has ubc activity when expressed in escherichia coli since ... | 1992 | 1310934 |
| detection of african swine fever viral antigens in paraffin-embedded tissues by use of immunohistologic methods and polyclonal antibodies. | tissues obtained from pigs inoculated with african swine fever virus (asfv), fixed by vascular perfusion using glutaraldehyde, and embedded in paraffin or araldite were used for an immunohistologic electron microscopic study. to detect asfv antigens, 4 methods were used on paraffin sections with or without pretreatment of the tissues. use of biotinylated anti-asfv antiserum combined with avidin-biotin complex and peroxidase proved to be the most suitable method, and antigen was detected in tissu ... | 1992 | 1510327 |
| african swine fever virus: generation of subpopulations with altered immunogenicity and virulence following passage in cell cultures. | virus subpopulations with variable virulence, immunogenicity, and infectivity to pigs were readily generated by passaging tengani isolate of african swine fever virus, either biologically cloned or uncloned, in vero cell cultures. avirulent virus populations which account for more than 99% of virus in an uncloned preparation of the 27th passage are laboratory artefacts, perhaps do not exist in nature. furthermore, attenuation of virulence did not occur uniformly in all subpopulations newly gener ... | 1992 | 1558888 |
| [light and electron microscopic findings in the intestine of spontaneous and experimentally-produced african swine fever]. | light and electron microscopical studies were carried out after experimental induced and spontaneous infection with african swine fever virus. the experimental infection was performed in 18 pigs divided into two groups consisting of 9 animals. the pigs of group i were inoculated with virulent isolate e 70, those of group ii with attenuated isolate e 75. two infected pigs of group i and one control animal were killed on days 3, 5 or 7 p.i., two pigs of group ii and one control animal were killed ... | 1992 | 1559460 |
| a gene homologous to topoisomerase ii in african swine fever virus. | a putative topoisomerase ii gene of african swine fever virus was mapped using a degenerate oligonucleotide probe derived from a region highly conserved in type ii topoisomerases. the gene is located within ecori fragments p and h of the african swine fever virus genome. sequencing of this region has revealed a long open reading frame, designated p1192r, encoding a protein of 1192 amino acids, with a predicted molecular weight of 135,543. open reading frame p1192r is transcribed late after infec ... | 1992 | 1316688 |
| amino acid sequence and structural properties of protein p12, an african swine fever virus attachment protein. | the gene encoding the african swine fever virus protein p12, which is involved in virus attachment to the host cell, has been mapped and sequenced in the genome of the vero-adapted virus strain ba71v. the determination of the n-terminal amino acid sequence and the hybridization of oligonucleotide probes derived from this sequence to cloned restriction fragments allowed the mapping of the gene in fragment ecori-o, located in the central region of the viral genome. the dna sequence of an ecori-xba ... | 1992 | 1583732 |
| comparison of the sequence of the gene encoding african swine fever virus attachment protein p12 from field virus isolates and viruses passaged in tissue culture. | comparison of the amino acid sequence of the african swine fever virus attachment protein p12 from different field virus isolates, deduced from the nucleotide sequence of the gene, revealed a high degree of conservation. no mutations were found after adaptation to vero cells, and a polypeptide with similar characteristics was present in an ibrs2-adapted virus. the sequence of the 5' flanking region was conserved among the isolates, whereas sequences downstream of the gene were highly variable in ... | 1992 | 1583733 |
| genetic manipulation of african swine fever virus: construction of recombinant viruses expressing the beta-galactosidase gene. | homologous recombination is shown to be specifically induced in vero cells by infection with african swine fever (asf) virus. the frequency of recombination induced by asf virus infection between cotransfecting plasmids is comparable to that found after infection with the prototype poxvirus, vaccinia virus. the induction of recombination is accompanied by replication of the plasmid templates in the asf virus-infected cells. an asf virus insertion/expression plasmid vector containing the escheric ... | 1992 | 1566585 |
| characterization of p30, a highly antigenic membrane and secreted protein of african swine fever virus. | we have identified and characterized a 30-kda phosphoprotein (p30) of african swine fever virus (asfv) that is synthesized, membrane localized, and released into the culture medium at early times after infection. sequence analysis of the p30 open reading frame predicts a highly antigenic protein with putative phosphorylation, glycosylation, and membrane attachment sites. | 1992 | 1604821 |
| cell culture propagation modifies the african swine fever virus replication phenotype in macrophages and generates viral subpopulations differing in protein p54. | we have detected 86 african swine fever (asf) virus-induced proteins in infected pig macrophages by two-dimensional electrophoresis. no differences among protein patterns of wild-type viruses could be observed by this methodology. however, during cell culture adaptation and propagation we have characterized changes in the molecular weight of the asf virus specified protein p54, which show direct correlation with both size and number of viral subpopulation variants generated during cell culture p ... | 1992 | 1604931 |
| morphogenesis of african swine fever virus in monkey kidney cells after reversible inhibition of replication by cycloheximide. | the late cytoplasmic phases of african swine fever virus (asfv) morphogenesis in monkey kidney cells have been studied by transmission electron microscopy, focusing attention on the synthesis of viral envelopes. morphogenesis was studied after reversible cycloheximide blockage of monkey kidney cells infected with asfv. asfv appears to synthesize its external and internal envelopes within the cellular cytoplasm, at the same time as the capsid is formed, with intracellular and extracellular virion ... | 1992 | 1605742 |
| structure of (+)-(s)-1,3-dimethyl-6-oxiranyl-2,4-pyrimidinedione showing anti-asfv activity. | c8h10n2o3, mr = 182.18, monoclinic, p2(1), a = 6.6405 (7), b = 7.9493 (9), c = 8.3662 (9) a, beta = 103.07 (1) degrees, v = 430.18 (8) a3, z = 2, dx = 1.41 mg m-3, lambda (cu k alpha) = 1.54184 a, mu = 0.879 mm-1, f(000) = 192, t = 298 k, r = 0.037 for 1247 reflections with fo greater than or equal to 4 sigma (fo). the configuration at c7 is s. the pyrimidine-2,4-dione ring is nearly planar [r.m.s. deviation: 0.010 (8) a] and is antiperiplanar with respect to the epoxide ring. this arrangement i ... | 1992 | 1605931 |
| an african swine fever virus gene with homology to dna ligases. | sequence analysis of the sali g region of the genome of a virulent isolate of asfv (malawi lil 20/1) has revealed an open reading frame with the potential to encode a 48 kilodalton (kd) polypeptide which has significant homology with eukaryotic and prokaryotic dna ligases. this asfv encoded gene also contains the putative active site region of dna ligases including the lysine residue which is necessary for enzyme-adenylate adduct formation, but lacks the c-terminal basic region conserved in othe ... | 1992 | 1614852 |
| role of the host cell nucleus in the replication of african swine fever virus dna. | an examination by autoradiography of african swine fever virus-infected alveolar macrophages pulse labeled with [3h]thymidine showed that, at early times of viral dna replication, the grains were localized exclusively in the nucleus in 20% of the cells, while in 45% the label was found in the cytoplasm. in the remaining 35%, newly synthesized dna was detected in both the nucleus and the cytoplasm. at later times, the percentage of cells with grains in the nucleus decreased considerably. pulse-ch ... | 1992 | 1585638 |
| swine leukocyte antigen and macrophage marker expression on both african swine fever virus-infected and non-infected primary porcine macrophage cultures. | swine leukocyte antigens (sla) and a macrophage specific marker were monitored on porcine macrophages cultured with or without macrophage colony stimulatory factor (m-csf) and on cells infected with african swine fever virus (asfv). sla expression was maximal either in the total cell extract or on the cell surface at 3-4 days of culture; after 4 days these values began to decrease. fluorescence analyses of immunostained macrophages cultured with or without m-csf indicated a major upward shift in ... | 1992 | 1632065 |
| african swine fever virus fatty acid acylated proteins. | labeling experiments with [3h]palmitic and [3h]myristic acids of african swine fever virus-infected vero cells have shown that 11 proteins induced during infection are covalently bound to myristic acid and that palmitic acid was not attached to viral proteins. the time course of synthesis of the myristylated polypeptides and the requirements of viral dna replication indicated that the myristylated proteins, with the exception of a 13-kda protein, belong to the late class of viral proteins. the m ... | 1991 | 1962463 |
| gel retardation analysis of ribonucleotide reductase gene expression in african swine fever virus. | | 1992 | 1633957 |
| a sequence comparison of the vp72 gene of african swine fever virus. | | 1992 | 1633960 |
| antiviral activity of sulfated polysaccharides against african swine fever virus. | the polyanionic substances lambda and kappa carrageenan, pentosan polysulfate, fucoidan, dextran sulfate and heparin were investigated for their inhibitory effect on the replication of african swine fever virus (asfv) in vitro. lambda carrageenan was the most efficacious with a selectivity index, as based on the ratio of the 50% cytotoxic concentration to the 50% antiviral effective concentration, of 120, followed by pentosan polysulfate with 30, kappa carrageenan 13.3 and fucoidan 10. dextran s ... | 1991 | 1713439 |
| a general method to cleave a known dna sequence at any site. | we describe a new method for obtaining dna fragments starting at a desired point where there is no recognition sequence for any known restriction endonuclease. a single-stranded dna containing the fragment of interest is annealed to a synthetic oligonucleotide hybridizing at the 5' end of the required fragment. then, a partially double-stranded dna is synthesized using the klenow fragment of dna polymerase i in the presence of the four deoxynucleoside triphosphates. the remaining single-stranded ... | 1991 | 1665337 |
| rapid and biologically safe diagnosis of african swine fever virus infection by using polymerase chain reaction. | in order to circumvent the need for infectious virus for the diagnosis of african swine fever (asf), we established the polymerase chain reaction (pcr) technique for the detection of asf virus (asfv) dna. a 740-bp fragment that originated from the conserved region of the viral genome was partially sequenced. from this sequence, four pcr primers and one oligonucleotide probe were designed and synthesized. a specific 640-bp pcr product was amplified by using oligonucleotides 1 and 5 as primers and ... | 1992 | 1734041 |
| repetitive nucleotide sequencing of a dispensable dna segment in a clonal population of african swine fever virus. | repetitive nucleotide sequencing of a dispensable genomic segment of a clonal population of african swine fever (asf) virus has been carried out to estimate the mutant frequency to neutral alleles. since no mutations have been detected in a total of 54026 nucleotides screened, the maximum mutant frequency is 5.5 x 10(-5) substitutions/nucleotide (95% confidence level). the result renders very unlikely the occurrence of hypermutational events during asf virus dna replication, at least within the ... | 1991 | 1685049 |
| induction of ribonucleotide reductase activity in cells infected with african swine fever virus. | infection of vero cells with african swine fever virus (asfv) resulted in a marked increase in ribonucleotide reductase activity. the induction of ribonucleotide reductase was detected early after infection and was proportional to the multiplicity of infection. inhibition of viral dna replication did not affect the induction of the enzyme. several characteristics could distinguish the virus-induced from the normal cell enzyme. asfv-induced ribonucleotide reductase was inhibited by magnesium, was ... | 1992 | 1736545 |
| variable regions on the genome of malawi isolates of african swine fever virus. | restriction enzyme site mapping showed that most bamhi and all clai sites were conserved on the genomes of 17 african swine fever virus isolates from separate disease outbreaks that occurred between 1982 and 1989 in malawi. however, frequent variation between virus genomes did occur due to addition or deletion of dna sequences at various positions along the genome and 11 virus genotypes could thus be distinguished among the 17 isolates analysed. length variations occurred at 10 different loci on ... | 1990 | 2230738 |
| modulation of splenic macrophages, and swine leukocyte antigen (sla) and viral antigen expression following african swine fever virus (asfv) inoculation. | expression of viral and major histocompatibility complex (mhc) antigens and localization of t cells and macrophages was studied in frozen tissue sections of spleens taken from normal pigs or from pigs inoculated with highly virulent lisbon 60 (l60), or with moderately virulent dominican republic 1978 (dr-ii), african swine fever virus (asfv) isolates. splenic sections from l60 inoculated pigs exhibited a large decrease in macrophage staining, whereas dr-ii infected animals appeared more intensel ... | 1992 | 1550493 |
| interferon cures cells lytically and persistently infected with african swine fever virus in vitro. | human interferon alpha (ifn-alpha) and interferon gamma (ifn-gamma) inhibit african swine fever (asf) virus replication in vero cells. ifn-alpha and ifn-gamma exert a synergistic inhibition. human tumor necrosis factor (tnf) does not inhibit asf virus replication in this cell line, but in combination with ifns it has antiviral enhancing activity. analysis of the mechanism of inhibition suggests that the action of these cytokines blocks a step that comes prior to dna replication. the 2'-5' a synt ... | 1990 | 1695091 |
| mapping and molecular characterization of a functional thymidine kinase from amsacta moorei entomopoxvirus. | a thymidine kinase (tk) gene from the entomopoxvirus of amsacta moorei (amepv) has been identified, mapped, cloned, and sequenced. the amepv tk was shown to be biologically functional as cloning of the gene into a tk-derivative of the orthopoxvirus vaccinia creates a tk+ virus. the gene has been localized to a 1.5-kb ecori-q dna fragment which maps to the far left end of the viral genome. sequence analysis reveals an open reading frame (orf) of 182 amino acids potentially encoding a polypeptide ... | 1992 | 1733099 |
| interferon-gamma production by african swine fever virus-specific lymphocytes. | peripheral blood mononuclear cells (pbmc) from inbred pigs that were immunized with autologous macrophages infected with the african swine fever (asf) virus ba71v, a nonvirulent virus isolate, proliferated and produced interleukin-2 in response to homologous and heterologous isolates of the asf virus. they produced, however, interferon (ifn) only when challenged in vitro with homologous or attenuated isolates of the asf virus, but not with heterologous or virulent isolates. the ifn was ph 2 labi ... | 1992 | 1738818 |
| expression in vivo and in vitro of the major structural protein (vp73) of african swine fever virus. | the vp73 protein was produced by in vitro transcription and translation from the xho i-bam hi fragment located between the cla i-n and cla i-h fragments of the viral genome. this dna fragment encodes a late mrna of about 2.6 kb detected in infected ms monkey and bhk hamster cells. the transcript was initiated at a site within two bases upstream of the translation initiation codon. the in vitro synthesized polypeptide shows the same molecular weight as the in vivo synthesized polypeptide, suggest ... | 1992 | 1550491 |
| virus survival in the environment. | viruses pass into the environment from clinically ill or carrier hosts; although they do not replicate outside living animals or people, they are maintained and transported to susceptible hosts. population concentrations and movement, both animal and human, have been steadily increasing in this century, enhancing transmission of respiratory and enteric viruses and compounding the difficulty of preventing environmental transmission. studies on environmental survival factors of viruses have been m ... | 1991 | 1782426 |
| [the population structure of the african swine fever virus based on the quantitative hemadsorption trait]. | subpopulation composition of 8 asfv isolates and variants differing in virulence was evaluated comparatively by their haemadsorption capacity. the "quantitative haemadsorption marker" was shown to be useful for characterization of the strains, virus population phenotypic heterogeneity and structure. the marker expression was found to correlate with virulence: attenuated variants had low haemadsorption and more subpopulation components with that shift, and vice versa. | 1991 | 1796589 |
| effect of macrophage-specific colony-stimulating factor (csf-1) on swine monocyte/macrophage susceptibility to in vitro infection by african swine fever virus. | swine cells of the monocyte/macrophage lineage (mm) proliferate and survive for several weeks in vitro in medium supplemented with the murine macrophage-specific hematopoietic growth factor, colony-stimulating factor 1 (csf-1). the extent to which mm, cultured in csf-1, supported african swine fever virus (asfv) growth in vitro was investigated. mm, cultured in medium with csf-1, were sensitive to infection and viral-induced cytopathogenic damage by both natural field isolates of asfv and fibrob ... | 1990 | 2281603 |
| experimental transmission of african swine fever virus by the tick ornithodoros (alectorobius) puertoricensis (acari: argasidae). | the soft tick ornithodoros puertoricensis fox has been found on the caribbean island of hispaniola (haiti and the dominican republic) where african swine fever (asf) was endemic from 1978 to 1984. to evaluate the vector potential of o. puertoricensis for african swine fever virus (asfv), second-instar nymphs were experimentally infected by feeding on a viremic pig that was infected with the dominican republic isolate (dr-ii) of asfv. subsequent infection rates and mean virus titers for individua ... | 1991 | 1770521 |
| inhibition of natural killer activity in porcine mononuclear cells by african swine fever virus. | the coincubation at 37 degrees c for 24 hours of swine peripheral blood mononuclear cells with african swine fever virus inhibited in part the natural killer activity shown by cells incubated without the virus. this inhibition depended on the dose of the virus and on the time that cells were incubated with it. when the virus preparation was fractionated by ultracentrifugation, most of the inhibitory activity was found in the sedimented fraction, where viral particles were present; however, the l ... | 1991 | 1780588 |
| glomerular pathology in surviving pigs experimentally infected with african swine fever virus. | twelve miniature pigs were inoculated with an attenuated african swine fever virus to study glomerular involvement in surviving pigs. in acute phase, kidneys were severely affected and displayed a glomerular capillary thrombosis with fibrin deposition in vascular lumen, detected by immunofluorescence. fibrin-positive deposits were progressively cleared between one to three months after infection in surviving pigs. the histological picture in kidneys of surviving pigs, up to one post-infection ye ... | 1991 | 1806048 |
| vaccinia virus-mediated expression of african swine fever virus genes. | bacteriophage lambda and plasmid clones containing african swine fever virus (asfv) dna inserts, which together covered more than 90% of the genome of a malawi asfv isolate (lil 20/1), were transfected into vaccinia virus (vv)-infected cells. expression of asfv-encoded proteins was assayed at late times after vv infection by immunoprecipitation of [35s]methionine-labeled proteins with hyperimmune serum from asfv-infected pigs, separation of immunoprecipitated proteins by denaturing polyacrylamid ... | 1991 | 1826575 |
| isolation and molecular characterization of the swinepox virus thymidine kinase gene. | swinepox virus (spv), the only member of the suipoxvirus genus, shows little antigenic relatedness or dna homology to members of the other poxvirus genera. a spv thymidine kinase (tk) gene was detected and mapped to the left end of the hindiii g fragment using degenerate oligonucleotide probes. cloning and sequencing of a 1.8-kb hindiii-bamhi fragment containing the spv tk gene revealed an open reading frame (orf) of 181 amino acids yielding a predicted polypeptide of mr 20.6 kda with significan ... | 1991 | 1853562 |
| the sequences of the ribonucleotide reductase genes from african swine fever virus show considerable homology with those of the orthopoxvirus, vaccinia virus. | two african swine fever virus (asfv) recombinant plasmids containing large inserts of dna have been sequenced at random, and translations of the dna sequence have been compared to libraries of vaccinia virus protein sequences. among other genes identified by their extensive homology with vaccinia virus genes were the large and small subunits of ribonucleotide reductase. a 5.5-kb fragment from the malawi (lil20/1) strain of asfv was identified as containing the genes for both these subunits. the ... | 1991 | 1871976 |
| rapid isolation of monoclonal hybridoma cultures by a 'fusion-cloning' method: the requirement for aminopterin. | hybridomas were generated by fusing the balb/c sp2/0 myeloma-like cell line with either: (i) splenocytes from balb/c mice immunized with foot-and-mouth disease virus (fmdv), rinderpest virus (rpv), peste des petits ruminants virus (pprv), african swine fever virus (asfv) or pig thymocytes; or (ii) lymph node cells from cattle immunized with fmdv. if the fusion mixtures were plated in cloning medium of methyl cellulose and hat medium, small hybridoma colonies developed which rarely survived. fusi ... | 1991 | 1954000 |
| detection of african swine fever virus by a biotinylated dna probe: assay on cell cultures and field samples. | african swine fever virus was detected in various samples using a molecular hybridization technique. a fragment located in a constant area of the viral genome was biotin-labelled. this probe, when present at a concentration of 100 ng/ml of the hybridization solution, could detect 10 pg of target dna immobilized on nitrocellulose with cellular dna and rna. the virus was evidenced after being passaged on monkey kidney cells, either 8 h post-inoculation (pi) if the multiplicity of infection (moi) w ... | 1991 | 1897870 |