failure to prove arenavirus infection among the small mammals from an endemic area of korean hemorrhagic the light of recent knowledge on a complex of diseases caused by a new group of viruses, arenaviruses, virological studies largely directed toward small field mammals were undertaken during 1973-1974 aiming at etiological clarification of korean hemorrhagic nephrosonephritis (khnn). specimens were collected in an endemic area of khnn located north to northeast of seoul. virus isolation tests with 299 urine specimens and 131 mite pools recovered from small mammals and 14 acute stage sera from ...197612383
editorial: lassa fever. 197546518
editorial: lassa or marburg or jo'burg. 197547490
letter: lassa by letter. 197552067
decreasing any viral infectivity in blood-smears for malarial parasite examination. 197874655
protection of rhesus monkeys from lassa virus by immunisation with closely related arenavirus. 197990819
lassa fever virus: properties and characteristics. 1979111436
[viral contamination in laboratories and hospital units].viral contamination is at least as important in hospital laboratories and wards as contamination by bacteria or microscopic fungi, but it is much more insidious and sometimes unrecognized. there are two main types: the first has a purely technical effect and only interest the virologist. this is contamination of reagents, reference strains, cell cultures, etc.., by foreign viral agents. it may be the cause of errors on diagnosis or regrettable errors of interpretation of certain experimental dat ...1975165448
arenaviruses. 1975168692
arenavirus taxonomy: a review.despite a late beginning, the construction of the arenavirus taxon and its placement in the scheme of the international committee on taxonomy of viruses has now been completed. the bringing together of the member viruses has already provided valuable indications of promising laboratory and field study approaches; in the future this classification will contribute further to our understanding of the natural history and disease processes of the human pathogens of the group.1975182395
morphology and morphogenesis of arenaviruses.arenaviruses have unique structural characteristics; they are pleomorphic, have a mean diameter of 110-130 nm, and consist of a membranous envelope with surface projections surrounding an interior containing ribosomes and filaments. virus particles bud from plasma membranes of infected cells and in many cases large intracytoplasmic inclusion bodies are formed. these characteristics allow generic identification, but not differentiation of individual viruses. ultrastructural identification of viru ...1975182396
antigenic properties of the arenaviruses.arenaviruses are known to show antigenic relationships in the complement-fixation (cf) and fluorescent antibody tests but not in the neutralization test. the humoral response to some of the arenaviruses is characterized by a dissociation between the antibodies determined by the cf test and those determined by the neutralization test and also by its late appearance following natural infection. investigations are reported showing that, as regards the cf test, junin, machupo, amapari, and tacaribe ...1975182397
the structure of rodent faunas associated with arenaviral infections.the biogeographical examination of rodent faunas associated with arenaviruses reveals two distinct patterns. lymphocytic choriomeningitis (lcm) virus is associated primarily with a single murid species, mus musculus, although it is also known to cause laboratory infections in other species. on the other hand, the arenaviruses from the western hemisphere are associated exclusively with a large and diverse group of cricetid rodents. studies to date, although limited, have not demonstrated their as ...1975182403
status of arenavirus vaccines and their application.a limited but definite need exists for vaccines against lassa, junin, and machupo viruses. medical and laboratory personnel, as well as defined high-risk population groups, require protection from these highly virulent agents. to date little work has been done on inactivated vaccines for these viruses. a live attenuated junin vaccine has been tested successfully in more than 600 persons, and a high-passage machupo virus strain has protected rhesus monkeys against lethal infection produced by a h ...1975182407
arenaviruses in perspective. 1978204386
[arenaviruses]. 1978206025
isolation of an arenavirus closely related to lassa virus from mastomys natalensis in south-east africa.five unidentified virus strains were recovered from the multimammate mouse ,mastomys natalensis, during the course of studies on arbovirus infections in mozambique. these agents were found to be morphologically and immunologically related to lassa virus. four of 19 sera from mastomys captured in the study area had antibodies to both lassa virus and one of the unidentified strains. although not definitive, the differences noted in results of complement fixation and indirect immunofluorescent test ...1977304387
a serological survey of lassa fever in liberia.a serological survey was undertaken at four liberian hospitals in 1974 in which serum samples were taken from 104 health workers and 61 patients. six persons had lassa fever antibodies: four midwives and two students of midwifery. of those persons who had lived in loffa county, 4 of 22 midwives were seropositive whereas none of the other 39 residents were positive (p = 0.014).1978310723
pathobiology of lassa fever. 1978350792
[marburg, lassa and ebola virus as cause of hemorrhagic fever]. 1978352653
lassa virus antibodies in hospital personnel in western liberia.the sera of 844 liberian hospital staff memebers were positive for lassa virus (lv) antibodies in a survey using the indirect fluorescent antibody technique (ifat). in two hospitals in lofa county near the sierra leone border, the prevalence, 15.4%, was significantly higher than the 8.4% in seven others. there were near differences between the prevalence among laboratory workers, 15.3%, and other workers, 7.7%, and between midwifery students, 21.2%, and midwives, 4.2%, suggesting their infection ...1979382467
[lassa fever and marburg disease]. 1978417467
lassa fever antibodies in hospital personnel in the plateau state of nigeria. 1979463337
a neutralization test survey for lassa fever activity in lassa, nigeria.5-8% of 434 sera collected in lassa village, nigeria, in august 1970 were positive by neutralization test for lassa fever (lf) virus. a second survey in march 1971 found 15 of 47 complete compounds tested in lassa, dille and yuba villages had at least one peron with serologically demonstrable experience with lf virus. 67% of positive compounds had more than one infected member. four of 17 hospital staff sero-converted between august 1970 and march 1971 without symptoms, evidence that subclinical ...1977560072
[new high-risk infectious diseases]. 1978566498
[recent lassa, marbourg and ebola viruses in african tropical viruses. i. semiology--physiopathology--diagnosis--treatment (author's transl)].three new viruses have been identified in africa during the present decade. they may cause sporadic cases or limited outbreaks, and they are probably endemic in areas which are still ill-defined. severe forms of infection lead to the haemorrhagic syndrome or to hypovolemic shock, the physiopathology of which is being studied. the case-fatality ratio of severe cases is between 30 and 85 per cent. nosocomial outbreaks have been observed, but they can be avoided if appropriate barrier nursing measu ...1978569288
[marburg, ebole and lassa virus infections]. 1979574072
[viral haemorrhagic fever].two outbreaks of haemorrhagic fever caused by a marburg-like virus occurred in the sudan and zaire from august to november 1976. the inital epidemiological investigations and emergency control measures were carried out by sudanese and zairian health personnel and several of them unfortunately died in the course of their duties. in view of the unusual gravity of the outbreaks and the unknown nature of the agent, assistance was provided by a who team in the sudan and a multinational team in zaire. ...1977590991
[tropical medicine. lassa fever in sierra leone]. 1978652080
serological survey for the detection of antibodies to lassa virus in india. 1978659905
biological species in praomys (mastomys) natalensis (smith), a rodent carrier of lassa virus and bubonic plague in africa.plague has been known from countries surrounding rhodesia from as early as 1935, but was first reported from rhodesia in 1974. part of our investigation of the complex ecosystem involving yersinia pestis is critical assessment of the evolutionary status of natural populations belonging to formal, taxonomic species of implicated rodents. we present data on chromosomal and hemoglobin variation in sympatric populations and laboratory produced hybrids that give unequivocal evidence for at least two ...1978677375
editorial: viral haemorrhagic fevers. 1975810212
editorial: lassa and marburg viruses. 1975810647
lassa fever: response to an imported february, 1976, a peace corps worker returned to the united states from sierra leone with an undiagnosed illness later recognized as lassa fever. to assess the risk of transmission and to contain a potential outbreak, we identified 552 contacts as having had exposure to the patient before the start of strict isolation procedures, and maintained intensive surveillance on these contacts for 21 days. at the end of the surveillance period, no illness had developed in contacts. one month later, a ...1977895819
[lassa fever]. 1976934650
lassa fever. 1976958983
lassa fever (arenaviruses) as a public health problem.two "new" virus infections, marburg and lassa fever, now constitute diseases of public health importance in several countries of africa, especially west africa. lassa fever has an insidious onset, is initially difficult to diagnose, has "nonspecific" clinical symptoms which have been confused with yellow fever and typhoid, shows evidence of persistent infection, is tremendously contagious, has a high mortality rate, and in particular exhibits unusual nosocomial propensity. it has also been shown ...19761026322
lassa fever. 19751040192
[lassa fever]. 19751043497
diagnosis of lassa fever and the isolation and management of patients.the clinical spectrum of lassa fever is described and discussed in terms of the possible pathophysiological events involved. early diagnosis is essential to permit prompt isolation of the potentially infectious patient. lassa fever may be suspected on clinical grounds, but specific early diagnosis depends upon isolation of the virus. virus isolation is best accomplished from serum obtained during the first 2 weeks of illness. the patterns of viraemia and virus excretion described in this paper a ...19751085225
handling patients with suspected lassa fever entering great britain.a special isolation unit has been created at the hospital for tropical diseases, london, for the reception of patients arriving in great britain from west africa with suspected lassa fever. the management of such patients and the operation of the unit are described. experience during the first eighteen months of operation has been very satisfactory and valuable lessons have been learned concerning the diagnosis and treatment of lassa fever and the nursing of patients.19751085226
arenavirus chemotherapy--retrospect and prospect.two groups of compounds, identifiable by structural similarity, have been found to interfere with the in vitro replication of arenaviruses. all 4 members of the benzimidazole group contain dipolar fused benzene and 5-membered nitrogen-containing rings and share potential chelating ability through the different bidentate structures formed with their side-chains. the biological activity of one of these compounds, metisazone, has been shown to depend on the presence of divalent metals of the first ...19751085227
the arenaviruses: some priorities for future this paper lassa virus is used as a model in pinpointing priorities for future research on the arenaviruses. suggestions for specific investigations and public health measures cover the detection of lassa virus infection, the pathology and therapy of the disease, and its prevention and control.19751085230
[lassa fever]. 19751102478
[viral hemorrhagic fever in man]. 19751103342
letter: imported diseases. 19751109675
editorial: lassa fever. 19751111738
letter: lassa fever. 19751115977
[lassa fever]. 19751118049
experimental lassa virus infection in the squirrel monkey.experimental lassa virus infection was investigated in a nonhuman primate in order to elucidate the target organs of the viral infection and the course of pathologic events. four squirrel monkeys (saimiri scirreus) were inoculated intramuscularly with lassa virus and sacrificed for organ titrations and histopathology, one each day, on days 7, 12, 14, and 28 after inoculation. the animals showed a variable clinical course, with an incubation period of 8 to 18 days. the virus was demonstrated to b ...19751163630
unrecognized diseases in africa. ii. lassa fever. 19751165154
haemorrhagic fevers. 19751169820
lassa virus hepatitis. observations on a fatal case from the 1972 sierra leone epidemic.during a recent outbreak of lassa fever in sierre leone, a 20-year-old woman developed an acute febrile disease with tonsillar exudates and hemorrhagic manifestations. lassa virus was isolated in cell cultures from pharyngeal secretions and pleural fluid and was identified by complement fixation. typical arenavirus particles were observed in these infected cell cultures. in a liver biopsy specimen, diffuse hepatocellular damage and focal necroses were evident, with a spectrum of liver cell chang ...19751227472
[problems of clinical diagnosis and therapy of a new arena virus infection (lassa fever)]. 19751229576
[ph-dependent fusion of eukaryotic cells, caused by arenaviruses, pathogenic and non-pathogenic for humans].the conditions necessary for fusion from inside (ffwi) of the bhk-21 cell culture affected by the lassa and mopeya arenaviruses were studied. the fusion was shown to occur only in the slightly acid medium and at lower ph meanings for the mopeya virus, than for the lassa virus.19921298876
[the immunogenic activity of the lassa virus structural proteins].the immunogenic properties of lassa virus gp1, gp2, and np polypeptides were studied in rabbits. lassa virus np polypeptide, in contrast to gp1 and gp2 polypeptides, was shown to induce the highest titres of antibodies determined by ifa and elisa tests. moreover, the antibody relative avidity experiment showed that the anti-np antibodies has elisa index of 0.63 whereas anti-gp1 and anti-gp2 antisera had those of 0.49 and 0.28, respectively.19921384241
the fusion of artificial lipid membranes induced by the synthetic arenavirus 'fusion peptide'.the fusing activity of the synthetic 23 amino-acid fragment (fusion peptide, fp) of the fusion protein of the lassa arenavirus membrane was tested in a model liposomal system. the resonance energy transfer between two fluorescent phospholipid probes was monitored in order to detect dioleoylphosphatidylcholine liposome fusion induced by the peptide. fusion rates were compared at different ph values, ionic strength and calcium concentrations. fp demonstrated fusing activity at ph 4.5-5.5, indicati ...19921390849
baculovirus expression of the glycoprotein gene of lassa virus and characterization of the recombinant protein.a recombinant baculovirus was constructed that expresses the glycoprotein gene of lassa virus (josiah strain) under the transcriptional control of the polyhedrin promoter. the expressed protein (b-lsgpc) comigrated with the authentic viral glycoprotein as observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page), was reactive with monoclonal antibodies (mabs) in western blots, and was glycosylated. although the recombinant protein was not processed into the mature glycopro ...19921413995
generation of reassortants between african arenaviruses.lassa (las) and mopeia (mop) viruses are african arenaviruses which are carried by wild rodents and occasionally transferred to humans. in humans and nonhuman primates, lassa causes mortality in 60% of untreated cases, whereas mopeia does not cause mortality and has been known to protect monkeys from lethal challenge with lassa. these two african arenaviruses also differ in their lethality for suckling outbred mice and in their plaque sizes under agar overlay. mop virus induces small plaques and ...19921585636
lassa fever encephalopathy: clinical and laboratory findings.clinical and laboratory findings are reported in nine patients who developed acute encephalopathy during the course of lassa fever. the encephalopathy manifested 3-17 days after disease onset with confusion, followed rapidly by tremor (seven patients), grand mal convulsions (seven), abnormal posturing (three) and coma (eight); focal neurological signs and evidence of raised intracranial pressure were not seen. eight patients died, most commonly from respiratory arrest following a protracted fit. ...19921597876
rats, fever and sudden deafness in sierra leone. 19921604723
inactivated lassa virus elicits a non protective immune response in rhesus monkeys.we attempted to protect three rhesus monkeys from lassa fever by vaccination with a preparation of purified whole lassa virus which had been inactivated by gamma irradiation. the vaccinated monkeys developed antibodies against the three major viral proteins of lassa virus demonstrated by radioimmunoprecipitation. when the three vaccinated monkeys and two unvaccinated control monkeys were challenged all five became severely ill and died. prior to death a secondary, high-titer antibody response to ...19921619397
[the interferon-inducing activity of the lassa virus in the body of inbred mice].the level and the time course of accumulation of endogenous interferon were studied in the blood sera of mice experimentally infected with lassa virus by the intracerebral route. the level of interferon correlated with case-fatality rate of the animals which may be important for the understanding of the pathogenesis of arenavirus infections.19901699360
lassa virus glycoproteins: antigenic and immunogenic properties of synthetic peptides to gp1.synthetic peptides corresponding to predicted lassa virus gp1 glycoprotein b-epitopes were used to study the antigenicity and immunogenicity of the protein. elisa results showed that guinea pig polyclonal anti-lassa virus serum bound effectively to peptides corresponding to amino acid residues 119-133 and 164-176 of the gp1 protein. essentially it did not react to a peptide corresponding to gp1 amino acid residues 234-256. sera obtained against peptides representing amino acid residues 119-133 a ...19901701079
antigenic relatedness between arenaviruses defined at the epitope level by monoclonal antibodies.monoclonal antibodies (mabs) were produced against two african arenaviruses, lassa virus and mopeia virus. competitive binding analysis of mabs identified four antigenic sites on the nucleoprotein (np), two on glycoprotein 1 (gp1) and six on glycoprotein 2 (gp2) of the josiah strain of lassa virus. 64 virus isolates from western, central and southern africa were all consistently distinguishable by mabs to certain epitopic sites on gp1, gp2 and np viral proteins. furthermore, mabs to lassa virus ...19911706408
[the therapeutic efficacy of ribamidil and virazole in experimental lassa fever in monkeys].the therapeutic efficacy of ribamydil and virasol was evaluated in experimental lassa fever in monkeys which received these drugs at various intervals after the onset of the clinical illness. ribamydil or virasol administered in the first day of fever protected from death 60% to 66% of the infected animals, but when the drugs were given 2 days after the onset of fever the number of survivors declined to 0.20%. when the treatment was started 4 days after the onset of fever none of the drugs preve ...19911858356
[the production of antibody-producing hybridomas to the lassa virus].the work deals with obtaining hybrid cell lines producing monoclonal antibodies to lassa arenavirus. to obtain preparations for the screening of hybridomas by indirect immunofluorescence techniques, the dynamics of the accumulation of lassa virus antigen in cell cultures vero and 4647 was studied. the maximum accumulation of the virus antigen in vero cells was shown to occur on day 3 after inoculation with a dose of 1.0 pfu/ml. the influence of different doses of gamma radiation on the infectiou ...19911872102
[the isolation and characteristics of reassortants between the lassa and mopeia arenaviruses].reassortants with a mixed phenotype were produced by combined inoculation of vero cells with lassa and mopeya viruses. these reassortants produced small plaques (mopeya virus phenotype) and were not pathogenic for newborn mice (lassa virus phenotype). the genotype of the reassortants was studied by dot hybridization experiments on filters using cdna-probes differentiating genome segments of these viruses. the reassortants were shown to have mopeya virus l-rna and lassa virus s-rna.19911882522
[experimental lassa fever in hamadryas baboons].intramuscular or aerogenic inoculation of baboons with lassa virus reproduced a severe form of the disease which clinically, pathoanatomically and virologically resembles the severe form of human lassa fever reported in the literature. the severity of monkey infection is demonstrated by rapid development of symptoms of general toxicity in the presence of fever, manifestations of hemorrhagic diathesis, high level of viremia and isolation of the causative agent from nasopharyngeal washings.19911882523
[fusion of artificial lipid membranes induced by synthetic "fusion peptide" of arenaviruses].the fusing capacity of lipid membranes of a synthetic 23-member peptide was studied. this hydrophobic peptide represents an analog of a predicted functional site ("fusion peptide") of the gp2 envelope protein of the lassa virus (family arenaviridae). fusion of small monolayer liposomes was detected by the method of resonance energy transfer between the fluorescent derivatives of the lipid, nbd-pe (donor) and rd-pe (acceptor). using this peptide, the ph-dependent fusing activity was found in lipo ...19911912065
sequence analysis of the s rna of the african arenavirus mopeia: an unusual secondary structure feature in the intergenic region.mopeia virus is an apparently nonpathogenic african arenavirus which can protect animals from subsequent challenge by the closely related lassa virus. as a step toward understanding these differences in pathogenicity and the means by which mopeia virus infection can protect against subsequent lassa virus infection, cdna clones corresponding to 3419 nucleotides of mopeia virus s rna were isolated and sequenced. two open reading frames, encoding the glycoprotein precursor (gpc) and nucleocapsid (n ...19911989384
exchange transfusion of a patient with fulminant lassa fever.we report a patient with fulminant lassa fever who responded dramatically to a 2.5-litre exchange transfusion of whole blood. on admission he was semicomatose with facial oedema and oral haemorrhage; his platelets showed markedly depressed aggregation to adp; and his plasma inhibited the aggregation responses of normal platelets in vitro. exchange transfusion resulted in rapid clinical improvement, recovery of platelet function, and disappearance of platelet-inhibitory activity in plasma. the pa ...19912041853
nucleotide sequence of the s rna of lassa virus (nigerian strain) and comparative analysis of arenavirus gene products.the nucleotide sequence of the small (s) genomic rna of lassa virus (strain ga391, of nigerian origin) has been determined. the rna has features which conform to those seen in most other arenavirus s rnas which have been characterised, including conserved terminal sequences, an ambisense arrangement of the coding regions for the precursor glycoprotein (gpc) and nucleocapsid (n) proteins and an intergenic region capable of forming a base-paired "hairpin" structure. comparison of the nucleotide se ...19912042397
[recombinant monoclonal antibodies to the lassa virus: the formation of reactive paratopes].eighteen hybrid lines secreting recombinant monoclonal antibodies to lassa virus were produced by fusion of mouse splenocytes with antibody-secreting x-63 myeloma cells. interrelations between the structure and reactivity of the antibodies were studied by different serological and immunochemical methods. monoclonal antibodies were divided into different groups according to their serological properties and macromolecular structure. a comparative analysis of the structure and reactivity of the rec ...19902082553
[experimental lassa infection in monkeys and its treatment with ribamidil]. 19902082557
[the comparative characteristics of the genetic traits of the lassa and mopeia viruses]. 19902219860
[the cultivation and physicochemical properties of the josiah strain of the lassa virus].data on the stability of lassa virus, josia strain, isolated from man to the effect of physicochemical factors (heating at 50 degrees c, solutions of urea and formalin of various concentrations, uv irradiation) as well as on the time course of this strain reproduction in cell lines of different origins are presented. recommendations for lowering of reactogenicity of the virus-containing material are given. the experimental results must be taken into consideration in the development and manufactu ...19902256317
[the isolation and characteristics of recombinant monoclonal antibodies to the lassa virus].recombinant monoclonal antibodies to lassa virus were produced. the reactivity of the monoclonal antibodies was studied by indirect fluorescence antibody (ifa) technique, enzyme-linked immunosorbent assay (elisa), and radioimmunoprecipitation method. the observed reactivity did not correlate with igg isotyping groups.19902267781
[the detection of a presumed fusion peptide comprising the surface glycoproteins of arenaviruses]. 19902267784
detection of lassa virus rna in specimens from patients with lassa fever by using the polymerase chain reaction.suitable oligonucleotide primers and probes were synthesized to amplify lassa virus (josiah strain)-specific nucleoprotein and glycoprotein gene fragments by using reverse transcription combined with the polymerase chain reaction (pcr). our primers did not amplify the related lymphocytic choriomeningitis virus. by using pcr, about 50 50% tissue culture infective doses could be detected in the supernatant of infected cells. furthermore, in all five serum specimens and four of five urine specimens ...19902279999
[immunization of rabbits with lassa virus].the parameters of humoral and cell-mediated immunity after inoculation of the infectious and inactivated antigen of lassa virus to rabbits which are insusceptible to this infection were studied. lassa virus antigen was demonstrated to induce synthesis of specific antibodies in rabbits the level of which was proportional to the dose of inoculation and the time of immunization. the results of leukocyte blastogenesis test and delayed type hypersensitivity test confirm the development of sensitizati ...19902363276
prediction of arenavirus fusion peptides on the basis of computer analysis of envelope protein sequences.theoretical search and selection criteria for putative fusion peptides of enveloped viruses are proposed. arenavirus fusion peptides are predicted on the basis of computer-assisted analysis of amino acid sequences of arenavirus envelope proteins and elements of their secondary and tertiary structure. accordingly, two regions of gp2 surface protein from 5 viruses of arenaviridae family have been detected with properties typical of fusion peptides of other enveloped viruses. one region, named pept ...19902387394
[lysosomotropic agents inhibit the penetration of arenaviruses into a culture of bhk-21 and vero cells].lysosomotropic agents (nh4cl, amantadine, chloroquine, monensin) which prevent acidification of intracellular vacuoles, when introduced into the culture medium before or during inoculation of cells (bhk-21, vero) with arenaviruses inhibit reproduction of these viruses completely or significantly. mozambique virus proved to be 10 times more sensitive to the effect of lysosomotropic agents than pichinde and lassa viruses. thus, arenaviruses have a ph-dependent stage at the beginning of the reprodu ...19902389568
[comparative evaluation of the antiviral efficacy of virazole and ribamidil in experimental lassa fever in monkeys].lassa virus administered to monkeys aerogenically induced in these laboratory animals a fatal disease modelling the severe course of human lassa fever. it was demonstrated experimentally that ribamydil, a soviet analogue of virasol, as well as foreign commercial virasol was therapeutically effective in experimental lassa fever in aerogenically infected monkeys.19902389569
[characteristics of monoclonal antibodies against lassa virus].some properties of monoclonal antibodies to the lassa virus have been characterized. the competitive immunoenzyme analysis has revealed the presence of at least three antigens in the lassa virus nucleoprotein.19872441254
[characteristics of the immune response in mice immunized with the inactivated lassa virus].the influence of humoral and cell-mediated immunity on the formation of resistance in mice immunized with inactivated lassa virus was evaluated. as a result of immunization, both nonspecific and specific immune response developed, the main rule in the formation of resistance belonging to specific immunity.19892474905
epitope mapping of the lassa virus nucleoprotein using monoclonal anti-nucleocapsid antibodies.monoclonal antibodies with differing specificity were prepared against the josiah strain of the lassa virus. all monoclonal antibodies were characterized by subclass determination and the immunofluorescence test against lassa, lcm (we & arm strain), junin, machupo, and other arenavirus antigens. in radioimmune precipitation tests using purified lassa virus antigen all monoclonal antibodies precipitated a single band of 60 kd, specific for the viral nucleoprotein (p 60). three domains (a, b, c) w ...19892476109
antibody prevalence against haemorrhagic fever viruses in randomized representative central african populations.between 1985 and 1987, 5,070 randomly selected persons living in 6 central african countries (cameroon, central african republic, chad, congo, equatorial guinea and gabon) were checked for serological evidence of haemorrhagic fever. rural and urban areas were studied, including ecoclimatic zones ranging from dry savana to tropical rain forest. virus-reactive antibodies were found with all antigens tested, and the global prevalence of positive sera was distributed as follows: crimean-congo haemor ...19892505350
antibodies to haemorrhagic fever viruses in madagascar populations.sera of 381 adult people from 5 areas in madagascar were tested by the indirect immunofluorescence method for antibodies against congo-crimean haemorrhagic fever and rift valley fever viruses (bunyaviridae), ebola (strains zaire and sudan) and marburg viruses (filoviridae), and lassa virus (arenaviridae). the highest prevalence rate was that of ebola virus (4.5%). as no haemorrhagic syndrome has been found associated with this virus, the possible presence of a less pathogenic, antigenically rela ...19892515626
preparation and biochemical characterization of lassa virus subvirion fractions.14c-labelled lassa virus was purified by isopycnic centrifugation and split to subvirion fractions. the purified virus was treated with nonionic detergents nonidet p-40 (np-40) and with octylglycoside. after ultracentrifugation in urographin density gradient, two subvirion fractions with buoyant density of 1.24-1.26 and 1.08-1.10 g/cm3 were obtained. the first fraction corresponded to the nucleocapsid of lassa virus: it contained a protein with molecular mass of 60 kda, the l and s segments of t ...19892569820
identification of lassa fever virus infection with recombinant nucleocapsid protein antigen. 19892572935
[lassa and mozambique viruses: cross protection in experiments on mice and action of immunosuppressants on experimental infections].the pathogenicity of mozambique virus for random-bred mice and cba mice was studied. in contrast to lassa virus, intracerebral inoculation of newborn zandom-bred mice with mozambique virus (1000 pfu/mouse) results in death of the animals. the pathogenic properties of both viruses for adult cba mice were found to be similar: intracerebral inoculation of the viruses caused death of the animals within 6-8 days, but not intraperitoneal inoculation. with the latter, they produced a population of immu ...19892609647
[dynamics of antigen and antibody accumulation in adult mice, infected with lassa virus]. 19892658319
[the first imported case of lassa fever in japan]. 19892724572
protection of guinea pigs from lassa fever by vaccinia virus recombinants expressing the nucleoprotein or the envelope glycoproteins of lassa virus.a recombinant vaccinia virus that expresses the nucleoprotein gene of lassa virus (josiah strain) under the control of the p7.5 promoter was constructed using the lacz coexpression transfer vector psc11. southern blot analysis demonstrated that recombination of the sequences inserted within the thymidine kinase gene of the transfer vector into the hindiii j fragment of vaccina virus genomic dna occurred properly. a 63-kda protein identical in electrophoretic mobility to authentic lassa nucleopro ...19892741340
[effect of immunosuppression on the development and outcome of an acute infection in mice caused by administration of the lassa virus].in experimental infection of mice with lassa virus, the infectious virus could be detected in all the organs and brain tissues tested. histopathological lesions were demonstrated in cerebral and spinal cord tissues only. roentgen irradiation in a dose of 500 r and cyclophosphamide protected mice against a lethal lassa virus dose. cyclosporin a in various doses exerted no effect on the outcome of the acute infection. the adoptive transfer of splenocytes from mouse donors inoculated intraperitonea ...19892763513
a plasma inhibitor of platelet aggregation in patients with lassa fever.previous studies have shown that haemorrhage in lassa fever is associated with abnormal in vitro platelet aggregation and a high mortality. in sierra leone we studied platelet aggregation in healthy local subjects, patients with laboratory-confirmed lassa fever and febrile patients in whom lassa virus infection was excluded. there were no significant differences in the mean platelet counts of these groups. patients with fulminant lassa virus infection showed a gross depression of in-vitro platel ...19892775659
[pathogenic machupo and lassa arenaviruses: the biochemical properties of virion rna and proteins].lassa virus purified in the isodensity sucrose concentration gradient had the following buoyant densities: 1.17 g/cm3 (sucrose), 1.19 g/cm3 (cesium chloride), 1.16 g/cm3 (urografin). similar parameters were obtained for machupo virus. virion rnas of these viruses contained 5 sedimentation classes of molecules: 30-31s, 28s, 22-24s, 18s, and 4-6s. experiments on hybridization of individual sedimentation classes of rna with an excess of poly(a)-containing rna from the infected cells as well as inhi ...19872825435
[identification of the mrna of the nucleocapsid proteins of pathogenic arenaviruses].total rna from cells infected with machupo and lassa viruses as well as individual sedimentation classes of these rnas were translated in the cell-free protein-synthesizing system from rabbit reticulocytes. the translation products were precipitated either with anti-machupo immune gamma-globulin or monoclonal antibodies to nucleocapsid protein (np) of lassa virus. both total rna and rna fraction with the sedimentation coefficient 15-16s promoted the synthesis of protein which comigrated in gel w ...19872829439
[template activity of poly(a+) and poly(a-) messenger rna of pathogenic arenaviruses].the total rna from cells infected with machupo and lassa viruses as well as poly(a+) and poly(a-) fractions of the rna were translated in the cell-free protein synthesizing system from rabbit reticulocytes. the translated products were treated with specific antibodies and analyzed in polyacrylamide gel electrophoresis. only poly(a-) fraction of rna coded for the synthesis of np protein in vitro. the mrnas for np protein of machupo and lassa viruses are supposed to contain no poly(a) sequences at ...19882848192
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