| the opposite temperature-sensitivity character (ts) in two attenuated flaviviruses, used for human immunization: 17d yellow fever and e5"14" (langat) viruses. a reappraisal of thoughts. | for the reproduction of the man-attenuated e5"14" clone of the langat virus (tick-borne encephalitis complex) in pig kidney epithelial cells, the temperature of 39 degrees c was shown as restrictive, whereas it was permissive for the 17d strain of yellow fever virus and three virulent strains of tick-borne encephalitis (western subtype) virus. the temperature of 36 degrees c permitted the reproduction of all viruses studied. the implication of genetic marker studies in the assessment of human ne ... | 1976 | 11663 |
| potentiation of langat virus infection by lead intoxication--influence on host defenses. | pathogenesis was studied in mice with moderate levels of lead intoxication after langat virus infection. both lead chloride and lead nitrate increased mortality by 40--50%. this increase was associated with decreased in vivo interferon and neutralizing antibody synthesis. the increased mortality was associated with enhancement of viral growth in peripheral tissues as evidenced by early appearing and long-lasting high titer viremia following lead intoxication. this resulted in early penetration o ... | 1977 | 20766 |
| graft-versus-host reactivity of langat virus-infected spleen cells in a syngeneic mouse system. | | 1976 | 63239 |
| an immunopathologic component in experimental togavirus encephalitis. | the effects of immune manipulation upon survival and histopathology in two experimental group b togavirus encephalitides were studied in inbred mice. the median survival time 8 days after intracerebral injection of langat virus increased to 10 days with an immunosuppressive course of cyclophosphamide, with concomitant reduction in the inflammatory response. adoptive immunization with immune lymphoid cells or serum also tended to prolong langat virus survival while increasing inflammation. surviv ... | 1975 | 171349 |
| the occurrence of vacuolated neurons in the brains of hamsters affected with subacute sclerosing encephalitis following measles or langat virus infection. | hamsters infected by the intranasal route with either hamster adapted langat virus passaged at least 10 times in hamsters and the hnt strain of measles virus passaged 149 times in hamsters, developed subacute sclerotic lesions in the pyriform cortex, and beginning from 2 months after infection, were accompanied by neuronal vacuolation with ballooning of the cytoplasm, especially in parts of the brain in close proximity of the sclerotic lesions. the vacuolated neurons resembled those seen in scra ... | 1975 | 173381 |
| further observations on subacute sclerosing encephalitis in adult hamsters: the effects of intranasal infections with langat virus, measles virus and sspe-measles virus. | passage by i.c. inoculations of suckling hamsters enhanced the virulence for adult hamsters of langat virus (tp21), neurotropic strain of measles virus (hnt) and sspe-measles virus (hbs), not only for i.c. infections but also for intranasal instillations. the various viral strains passaged in hamsters showed a great similarity of behaviour including the ability of producing in a proportion of apparently unaffected survivors a subacute sclerosing encephalitis, leading to atrophy of parts of the b ... | 1976 | 178335 |
| isolation of langat virus from haemaphysalis papuana thorell in thailand. | a strain of langat virus (lgt), t-1674, was isolated from a pool of haemaphysalis papuana thorell collected in the forest of khao yai national park in central thailand. the isolated virus was found to have growth and antigenic similarity to the prototype langat strain (tp-21). this is the first report of a natural infection of haemaphysalis ticks with lgt and of the isolation of this arbovirus in thailand. the wide distribution of known vectors of lgt in thailand suggests that the virus may be p ... | 1976 | 180846 |
| enhanced resistance of mice to infection with langat (tp21) virus following pre-treatment with sindbis or semliki forest virus. | significant protection to heterologous i.c. challenge with the flavovirus langat occurred after a single i.c. injection of avirulent strains of the alpha viruses semliki forest or sindbis given 1 day to 5 weeks before challenge. some protection also occurred after an i.p. infection with these viruses. we consider that the protection afforded by the alpha viruses is due to interference with the multiplication of langat virus and is related to the maximum level of brain infectivity reached in the ... | 1976 | 187719 |
| reactions of egyptian human and rodent sera to langat virus antigens. | | 1977 | 198509 |
| potentiation of the neurovirulence of langat virus infection by lead intoxication in mice. | | 1978 | 214336 |
| [characteristics of the response of mice with temporary immunodepression to the administration of live or inactivated vaccine against tick-borne encephalitis]. | mice with immunity defects caused by administration of cyclophosphane were inoculated with an inactivated vaccine or langat virus (tp-21 strain) considered to be an approximate model of the vaccine against tick-borne encephalitis. in mice with depressed immune response, the asymptomatic infection caused by langat virus turns into acute form and encephalitis with a fatal outcome develops in 86--100%. pre-treatment with inactivated tick-borne encephalitis vaccine did not protect the animals with t ... | 1979 | 217179 |
| ultrastructural and virological aspects of langat virus-induced sspe in suckling hamsters. | the morphology of subacute sclerosing panencephalitis (sspe) lesions in hamsters following i.p. inoculation of langat virus was studied by light microscopy and electron microscopy. the lesions' temporal relationship to virus presence and antibody production was studied by immunofluorescence, virus isolation from brains and brain cell cultures, and by antibody assay of serum and spinal fluid. all 10-day-old hamsters infected with langat virus developed sspe lesions, most prominently in the cerebe ... | 1979 | 231978 |
| a live vaccine against tick-borne encephalitis: integrated studies. i. basic properties and behaviour of the e5 "14" clone (langat virus). | the course of plaque segregation from the langat e5 strain of the e5 "14" clone is described. the virus, displaying an ic+ sc s plus or minus t e u s character, reproduced at 35 and 37, but not at 39 degree c. in subcutaneously (sc) inoculated monkeys, viraemia lasted for 2--4 days without detectable central nervous system (cns) involvement. in sc inoculated 8--10 g mice, the infection was manifested only by a transient trace viraemia, but caused a marked resistance against challenge with virule ... | 1975 | 239576 |
| a live vaccine against tick-born encephalitis: integrated studies. iii. response of man to a single dose of the e5 "14" clone (langat virus). | the clinical and immunological events in volunteers following administration of 5 and 6 dex newborn mouse intracerebral ld5o (nmicld5o) of the e5 "14" virus clone, segregated from the langat tp21 e5 strain (tick-borne encephalitis-te-complex) and propagated in 7 days old spf chick embryos, are reported. the experimental vaccine, containing the cloned virus, carrying a set of genetic markers of an ic(+) sc s(+/-) t e u (s) n character, caused in volunteers no clinically recognizable effects, but ... | 1975 | 239578 |
| cloning and sequence analysis of the genes encoding the nonstructural proteins of langat virus and comparative analysis with other flaviviruses. | langat virus, a member of the family flaviviridae is antigenically very similar to highly pathogenic tick-borne encephalitis viruses. we cloned and sequenced the complete nonstructural gene-coding region of langat virus (strain tp21) and compared the deduced amino acid sequences of each nonstructural protein to those of other flaviviruses. by alignment with the reported amino acid sequences of the nonstructural proteins of several flaviviruses, we were able to predict proteolytic cleavage sites ... | 1992 | 1316684 |
| t-cells of virus-infected mice produce a lymphokine which activates the autoreactivity of intact mouse lymphocytes. | the role of lymphokines was estimated in induction of autoreactive t-cells during langat virus infection in mice. it was shown that in vitro cultured splenocytes from virus-infected animal containing autoreactive lymphocytes (arl) spontaneously produce a lymphokine which is capable to activate the autoreactivity of lymphocytes derived from the spleen of intact syngeneic mice. the capacity of this lymphokine to activate the autoreactivity of acceptor cells within 2 hr was demonstrated by local gr ... | 1991 | 1683123 |
| fusion activity of flaviviruses: comparison of mature and immature (prm-containing) tick-borne encephalitis virions. | the fusion activity of flaviviruses [tick-borne encephalitis (tbe) virus and japanese encephalitis virus] was assessed by inducing fusion from without of c6/36 mosquito cells with purified virus preparations. membrane fusion and polykaryocyte formation was observed only after incubating the viruses at acidic ph. two groups of monoclonal antibodies reacting with distinct non-overlapping antigenic domains on the tbe virus protein e inhibited fusion from without. one of these domains contains the m ... | 1991 | 1710648 |
| sequence of the genes encoding the structural proteins of the low-virulence tick-borne flaviviruses langat tp21 and yelantsev. | the structural protein coding regions of the genomes of langat virus (strain tp21) and yelantsev virus, which was originally described to be a low virulence natural isolate of tick-borne encephalitis virus, were cloned and sequenced. these viruses had both been used as experimental live vaccines against tick-borne encephalitis in czechoslovakia and russia, respectively. peptide mapping and monoclonal antibody binding experiments yielded identical reaction patterns for langat virus and yelantsev ... | 1991 | 1720591 |
| the relationship between the flaviviruses skalica and langat as revealed by monoclonal antibodies, peptide mapping and rna sequence analysis. | the flavivirus skalica was isolated from a bank vole in czechoslovakia in 1976. it can be serologically distinguished from prototype strains of tick-borne encephalitis (tbe) virus and has a decreased virulence for adult mice. we have further defined the relationship of skalica virus to other members of the tbe serocomplex (tbe european and far eastern subtypes, langat and louping ill virus) by using a panel of 22 monoclonal antibodies, peptide mapping and rna sequence analyses. by these criteria ... | 1991 | 1847173 |
| comparison of skalica, hypr, and langat viruses by kinetic haemagglutination-inhibition test. | the skalica virus has been compared with hypr and langat viruses by kinetic haemagglutination-inhibition (hi) test. using hypr antigen, differences were observed between skalica, hypr, and langat viruses. by the use of skalica antigen, a close relationship between hypr and skalica viruses was detected, however, it was possible to differentiate the langat virus. when langat antigen was tested, a close relationship among all the three viruses was found. | 1990 | 1975983 |
| replication of langat virus in immunocompetent cells of mice subjected to immobilization stress. | immobilization stress (hypokinesis) in balb/c mice may aggravate asymptomatic infection with langat virus (strain tp-21) as evidenced by 4-fold increased lethality in comparison with control animals. the virus levels in the spleen and brain of stressed and infected mice and the in vitro yield of the virus in immunocompetent cells derived from stressed mice were significantly higher than in controls. enhanced virus replication in latter cells may contribute to increased accumulation of the infect ... | 1990 | 1980400 |
| [role of antigen-nonspecific suppressors occurring in stress in the pathogenesis of langat virus infection in mice]. | stress factors of different nature activate antigen-nonspecific suppressors inhibiting different mechanisms of immune response in mice. the adoptive transfer of the population of immunocompetent cells containing stress-induced suppressors to mice infected with langat virus has been found to lead to the activation of asymptomatic infection. the data obtained in this investigation indicate that the above-mentioned mechanism of the development of antigen-nonspecific immune deficiency is of importan ... | 1987 | 2448977 |
| [a survey of antibodies to arboviruses in residents in south-western part of yunnan province]. | in order to provide serological evidence for arbovirus infection in yunnan province, 760 samples of human sera collected from nine counties in south-western part of yunnan province were examined for hi antibodies to 11 arboviral antigens. the viruses used in this experiment included 3 alphaviruses (may, vee and chik) and 8 flaviviruses (je, mve, kun, den3, den4, kfd, lgt and pow). 275 samples were found positive for hi antibodies to alphaviruses (36.2%) and 189 of them (68.7%) reacted with may v ... | 1989 | 2544277 |
| [the possibility of preparing a live vaccine against tick-borne encephalitis from malay langat virus tp-21]. | | 1989 | 2560847 |
| 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 |
| detection of virus-specific antigen in the nuclei or nucleoli of cells infected with zika or langat virus. | two monoclonal antibodies (mabs) with molecular specificities for either the viral envelope glycoprotein (mab 541) or the non-structural ns1 glycoprotein (mab 109) were derived using west nile and yellow fever (yf) viruses respectively. their antigenic reactivity with a large number of flaviviruses was tested by indirect immunofluorescence microscopy. both produced cytoplasmic fluorescent staining patterns with the homologous virus against which they were raised. additionally, mab 541 reacted wi ... | 1988 | 2841406 |
| virus-induced decrease in the activity of serum blocking factor(s): a mechanism of activation of the autoreactive t effectors in graft versus host reaction and of controlling t suppressors. | it has been shown that serum blocking factor(s) (sbf) previously detected in normal mice bind(s) to receptors on the surface membranes of virus-induced autoreactive t lymphocytes (artl) and to that of artl activity inhibiting t suppressors (tsar). the interaction of sbf with the receptors is reversible, h-2 restricted and associated with the inhibition of functional activity of the tested t lymphocyte populations. in mice during acute tick-borne encephalitis (tbe), in the course of inapparent in ... | 1985 | 2859760 |
| formation of autoimmune effectors after transfer of virus-induced autoreactive precursors to syngeneic intact receptor animals. | we verified the assumption that autoimmune responses underlie immunosuppression developing in the course of virus infection. it has been shown by adoptive transfer that administration of langat-virus-induced autoreactive lymphocytes (arl) to the syngeneic recipient is followed by accumulation of autoreactive effectors (ae) eliciting a graft-verus-host reaction (gvhr) in the syngeneic system (aegvhr). in addition, cytotoxic t-lymphocytes (aec) appeared against the syngeneic macrophages. this effe ... | 1987 | 2894142 |
| antibody-dependent enhancement of tick-borne encephalitis virus infectivity. | fourteen mouse monoclonal antibodies raised against tick-borne encephalitis virus (tbev) and polyclonal antisera raised against six other flaviviruses, edge hill (ehv), japanese encephalitis (jev), langat (lgtv), louping ill (liv), west nile (wnv) and yellow fever (yfv), were tested for their ability to enhance the replication of tbev in cells of the mouse macrophage-like line p388 d1, and for their reactivity in elisa and haemagglutination inhibition (hi) tests. irrespective of their specificit ... | 1985 | 2991448 |
| [role of virus-induced autoreactive t-lymphocytes, t-suppressors and the serum factor regulating their activity in the pathogenesis of experimental infection caused by the langat virus in mice]. | the precursors of autoreactive t-lymphocytes (partl) have been detected in the spleen of mice infected with langat virus. when introduced into syngeneic recipients, partl differentiate in their lymph nodes into autoreactive t-lymphocytes (artl) causing a fatal autoimmune disease in the syngeneic recipients in vivo and capable of destroying syngeneic cell cultures in vitro. in the thymus of mice infected with langat virus t-suppressors (ts) inhibiting the differentiation of partl into artl have b ... | 1985 | 2998127 |
| [course of an experimental infection caused by the langat virus in mice against a background of restricted movement-related stress]. | | 1986 | 3026100 |
| [study of immunological mechanisms of action of temperature and emotional stress factors in experimental flavivirus infections]. | the influence of two stress factors, sharp changes in temperature and hypokinesia, on the course of experimental tick-borne encephalitis and langat virus infections in mice has been studied. the data obtained in this study indicate that both factors produce defects in t- and b-cell-mediated immunity, accompanied by the activation of asymptomatic infection and the decrease of the mean survival time in acute infection. these two stress factors, differing in their intensity and nature (physical and ... | 1986 | 3030031 |
| in vitro evidence for a cell-mediated component of the immune response in mice given the highly attenuated e5 "14" langat virus (the tick-borne encephalitis complex). | | 1973 | 4148122 |
| langat virus encephalitis in mice. i. the effect of the administration of specific antiserum. | | 1968 | 4175597 |
| experimental infection of monkeys with langat virus. 3. infection produced by virus feeding. | | 1969 | 4305203 |
| multiplication of langat virus in the tick ixodes ricinus. | | 1972 | 4401074 |
| stimulation of active immunity to langat virus in the presence of maternal antibody. | | 1972 | 4635160 |
| [stimulating effect of langat virus on reproduction of mycoplasma laidlawii in combined infection of a primary culture of chick embryo cells]. | | 1972 | 4672317 |
| subacute sclerosing encephalitis in adult hamsters infected with langat virus. | | 1973 | 4689822 |
| langat virus and vaccination against infections by the tick-borne complex of group b arboviruses. | | 1967 | 4872428 |
| langat virus encephalitis in mice. ii. the effect of irradiation. | | 1968 | 4877756 |
| a chick embryo attenuated strain (tp21 e5) of langat virus. i. virulence of the virus for mice and monkeys. | | 1966 | 4958356 |
| a chick embryo attenuated strain (tp21 e5) of langat virus. ii. stability after passage in various laboratory animals and tissue cultures. | | 1966 | 4958357 |
| experimental infections of monkeys with langat virus. i. comparison of viremia following peripheral inoculation of langat and japanese encephalitis viruses. | | 1966 | 4959333 |
| experimental infection of monkeys with langat virus. ii. turnover of circulating virus. | | 1967 | 4960867 |
| histological studies of the monkey neurovirulence of group b arboviruses. iv. evaluation of an attenuated strain (e5) of langat virus. | | 1968 | 4969351 |
| material for the study ofvariation in the malayan langat virus (tp-21 strain). | the lack of genetic uniformity of the malayan langat virus, tp-21 strain isolated from ixodes granulatus ticks in malaya, was demonstrated.increased pathogenicity of the virus for white mice and rhesus monkeys after passage through chick-embryo fibroblast cultures at temperatures of 36 degrees c and 40 degrees c is due to the selection of the pathogenic virus particles which are always present in the initial brain-tissue suspension of the tp-21 langat strain.the frequency of the occurrence of pa ... | 1968 | 4973556 |
| an electron microscope study of langat virus in tissue culture of the non-neuronal cells of mouse brain. | | 1971 | 5111710 |
| an electron microscopic study of langat virus encephalitis in mice. | | 1971 | 5111711 |
| [effect of mycoplasma-viral infection of a primary culture of chick embryo cells on interferon production induced by langat virus]. | | 1971 | 5167284 |
| experience in the study of a live vaccine made from the tp-21 strain of malayan langat virus. | the reaction-causing properties and immunogenicity of 2 cloned variants of the malayan tick virus, langat tp-21 strain, were studied. one clone, which was not pathogenic for rhesus monkeys when inoculated intracerebrally, caused the formation of antibody in moderate titre against tick-borne encephalitis virus in over 70% of persons given 2 inoculations of a live vaccine prepared from it. the other variant, which was pathogenic for rhesus monkeys, was characterized by greater immunogenicity but w ... | 1968 | 5303908 |
| langat virus. differentiation of strains of reduced pathogenicity suitable for vaccines. | | 1969 | 5355232 |
| role of serum protective factor (spf) in langat virus infection of neonatally thymectomized, cyclophosphamide-treated, or antilymphocyte-treated mice. | | 1969 | 5361570 |
| [the effect of certain mycoplasma on the formation of plaques by langat virus in a primary culture of chick embryo cells]. | | 1969 | 5377945 |
| role of serum protective factor and neutralizing antibody in pathogenesis of experimental infection with langat virus in mice. | | 1970 | 5459024 |
| antilymphocyte serum and tissue culture used to investigate role of cell-mediated response in viral encephalitis in mice. | antilymphocyte serum given to suppress selectively the cell response to langat virus in swiss albino mice prolonged the average survival times. in vitro, lymph-node cells from virus-immunized mice were strongly cytotoxic for syngenic non-neuronal brain cells infected with virus. the implications of these findings are discussed, with particular reference to the concept of autoimmunity. | 1970 | 5472783 |
| [neuropathology of encephalomyelitis caused by langat virus in the white mouse]. | | 1969 | 5789733 |
| effects of storage on the survival of langat virus in the tick, ixodes ricinus (l.). | | 1965 | 5827573 |
| a chick embryo attenuated strain (tp21 e5) of langat virus. 3. the ability to protect against homologous virus and powassan virus in cross-challenge experiments. | | 1966 | 5920389 |
| [analysis of the neurovirulent and immunogenic properties of clones isolated from a population of langat virus (strain tp-21)]. | | 1966 | 6002458 |
| neuropathological changes following treatment of human malignant disease with langat virus. | | 1967 | 6027440 |
| the course of langat virus infection in mice. | | 1967 | 6051242 |
| [role of virus-induced cytotoxic autoreactive t-lymphocytes and t-suppressors in the pathogenesis of an experimental infection in mice cause by the langat virus]. | in the spleens of mice experimentally infected with langat virus there accumulate precursors of autoreactive cytotoxic t-lymphocytes (arctl) which differentiate into mature lymphocytes when inoculated into the popliteal lymph nodes of syngeneic intact recipients. arctl inoculated intravenously into the intact or langat virus-infected syngeneic mice produce a fatal autoimmune disease characterized by the affection of the liver and spleen. inoculation of arctl into the infected recipients is accom ... | 1984 | 6087569 |
| antigenic analysis of flaviviruses with monoclonal antibodies against negishi virus. | twelve monoclonal antibodies against negishi virus were obtained and characterized by hemagglutination inhibition (hi) and neutralization (nt) tests using five flaviviruses isolated in the pan-pacific region. the reaction pattern of the antibodies showed that negishi virus was most closely related to langat virus, followed by 3-arch, je and apoi viruses in that order. hemagglutinating (ha) antigen of the virus had distinct hi relating sites which were negishi virus specific, tick borne encephali ... | 1984 | 6096680 |
| [effectors of in vivo delayed hypersensitivity in experimental flavivirus infections and vaccination against tick-borne encephalitis in mice]. | the development of experimental infections caused by tick-borne encephalitis (tbe) virus, langat virus and dengue virus type 2 in mice or the immunization of these animals with live yellow fever vaccine (prepared from strain 17d) and inactivated tbe vaccine were accompanied by the formation of delayed hypersensitivity (dh) to viral antigens, determined in vivo. in experimental tbe infection the effectors of dh were identified as t-lymphocytes whose action was specific and followed the rule of h- ... | 1984 | 6098109 |
| restricted replication of the e5"14" clone of langat tp21 virus (from the tick-borne encephalitis complex) in cns of subadult mice. | subadult icr mice were infected with the low virulent langat virus tp21 e5 strain clone "14" belonging to the tick-borne encephalitis (tbe) complex by subcutaneous (s.c.) and intracerebral (i.c.) routes. from 5 to 6 days post infection (p.i.), no virus was detected in cultured brain fragments of mice, which received 10(6) ic ld50 into interscapular area. acute lethal encephalitis with lesions confined to the vicinity of the inoculation area (parietal cortex, basal ganglia, thalamus) has develope ... | 1982 | 6132543 |
| concentration of murine antigen-specific transfer factor of defined potency. | dialysates containing transfer factor (tf) activity were prepared from lyzed splenic cells of spf mice immunized with live, peripherally avirulent langat virus (tp21 e5 "14" clone) from the tick-borne encephalitis (tbe) complex. the amount of tf was estimated by its capacity to generate in recipient inbred c3h mice cytotoxic t lymphocytes inducing lysis of tbe virus-infected target cells as demonstrated by 51cr--release assay. a 100 to 1000-fold concentration of tf activity was achieved by combi ... | 1983 | 6138984 |
| in vivo inhibition by intact mouse serum of the activity of the flavivirus-induced t-suppressors of autoreactive t-lymphocytes. | in the serum of healthy mice a factor was found inhibiting the in vivo effect of t-suppressors of autoreactive t-lymphocytes (tsart1) induced in mice by tick-borne encephalitis (tbe) virus, langat virus, dengue virus type 2 (d2) and attenuated strain 17d of yellow fever virus. activity of the serum factor (s) was demonstrated providing that the tsart1 had h-2 antigens completely or partially identical with the h-2 antigens of serum donors. the activity was not connected with destruction of tsart ... | 1984 | 6147997 |
| cell-mediated immunity in flavivirus infections. i. induction of cytotoxic t lymphocytes in mice by an attenuated virus from the tick-borne encephalitis complex and its group-reactive character. | the lytic activity of splenocytes from c3h mice immunized with a highly attenuated line of langat virus [tick-borne encephalitis (tbe) complex] was determined by the in vitro 51cr release assay on tbe virus (western subtype)-infected target l929 cells. after the spleen cell suspensions were depleted of t cells with anti-mouse theta serum, or of b cells with anti-mouse immunoglobulin, the cytotoxic effect was found dependent on the presence of t lymphocytes. during immunization with langat virus, ... | 1981 | 6165230 |
| dialysable specific transfer factor in mice immunized with attenuated langat virus from the tick-borne encephalitis complex: generation, action and quantitative assay. | cytolytic t lymphocyte assay was developed in order to measure the response of inbred c3h mice to dialysable specific transfer factor (stf), induced in subadult outbred mice by one shot immunization with the attenuated langat virus. the first stf activity in mice splenic leukocytes was detected between 48-72 hr after virus administration. the conversion of splenic t-cell cytotoxic response in c3h mice in vivo occurred between 15-21 hr after stf administration. the killing activity of t-cells, in ... | 1982 | 6188353 |
| antigenic relationships among viruses of the tick-borne encephalitis complex as studied by monoclonal antibodies. | tick-borne encephalitis (tbe) monoclonal antibodies showed haemagglutination-inhibiting (hi) activity against viruses belonging to the tbe complex except of powassan virus. the hi titre with kyasanur forest disease virus was lower than with tick-borne encephalitis virus, when monoclonal antibodies were incubated with the antigen at +4 degrees c for 30 min. langat virus could be distinguished from other viruses of the tbe complex when the antigen was incubated with monoclonal antibodies at +4 deg ... | 1984 | 6201061 |
| [the course of flavivirus infections in mice in the presence of the graft versus host reaction under conditions of 2-way incompatibility]. | the graft versus host reaction (gvhr) under conditions of two-way incompatibility was shown to increase average longevity (al) of mice with experimental tick-borne encephalitis (tbe) and to activate asymptomatic infection caused by langat virus. experiments with tbe virus demonstrated participation of viable t lymphocytes in gvhr. inhibition of function of both humoral and cellular immunity was shown to occur in gvhr. the assumption that the increase in the average longevity in tbe is associated ... | 1980 | 6247848 |
| replication of tbe and langat viruses in cells from immune individuals. | the replication of tbe virus and langat virus in cells of immune and non-immune individuals was compared in phytohemagglutinin (pha)-stimulated and non-pha-stimulated cultures and also following infection with low and high infection multiplicity. following infection of spleen cells from langat-immune mice with langat virus having a high infection multiplicity, higher virus replication rates than in non-immune cells were found to be present. replication of langat virus was generally superior to t ... | 1980 | 6252718 |
| [features of immunogenesis in simians infected with attenuated strains of tick-borne encephalitis and langat virus]. | certain parameters of humoral and cellular immunity induced by attenuated tick-borne encephalitis (tbe) and langat virus strains were studied in monkeys. the immunogenic activity of the strains inoculated subcutaneously and intracerebrally was manifested by two processes: synthesis of specific antibody and cellular immune response. the highest titers of humoral immunity in n, hi, and cf tests were observed to homologous viruses. the immune response to both homologous and heterologous viruses cou ... | 1981 | 6267819 |
| [effect of the tahyña virus on langat virus persistence in the central nervous system of the mouse]. | the features of development of a mixed infection in which one of the infectious agents (tahyña virus) had a marked immunodepressive activity and the other (langat virus) caused predominantly asymptomatic course of the disease were studied. successive infection with these agents increased the severity of the disease (lethality in monoinfection 7-18%, in mixed infection 57%). at the same time the duration of persistence in the brain of mice of langat virus but not of tahyña virus increased up to 1 ... | 1981 | 6278778 |
| [mechanisms of in vivo suppressive effect of togaviridae and bunyaviridae on the activity of effectors of graft vs host reaction]. | experiments on mice demonstrated the ability of 3 flaviviruses and 1 bunyavirus to suppress the activity of the effectors of the graft-versus-host (gvh) reaction. the conditions of the suppression of the primary immunological recognition were shown to differ in infections caused by different viruses. in experimental flavivirus infections caused by langat, dengue 2 or yellow fever (strain 17d) viruses t-suppressor cells were activated, and their activity was realized only in respect to syngeneic ... | 1982 | 6283771 |
| [functional activity of the macrophage elements of animal peritoneal exudate in the process of infection by tick-borne encephalitis complex viruses]. | investigations of the functional activity values of macrophages showed that free peritoneal macrophages of random-bred mice and guinea pigs participated in primary immune response to a single subcutaneous inoculation of the pan strain of tick-borne encephalitiss virus. tr-21 strain of langat virus, and the 237 strain, an experimentally attenuated variant of the latter. when the mice developed an acute infection, functional changes of macrophages were characterized by increased phagocytic activit ... | 1980 | 7423974 |
| the langat model for tick-borne encephalitis virus. specific detection by rt-pcr. | we have developed a reverse-transcriptase polymerase chain reaction assay for rapid detection of langat (lgt) virus, a flavivirus that is closely related to the highly pathogenic tick-borne encephalitis (tbe) viruses. unlike tbe viruses, lgt virus exhibits a significantly lower virulence for man. the assay serves as a safe alternative for the development and optimization of specific assays for the highly pathogenic subtypes of tbe viruses that are endemic throughout much of europe, the former so ... | 1993 | 7505284 |
| [characteristics of neurovirulence, stability, and immunogenicity of attenuated variants of tp-21 langat virus]. | clones of langat tp-21 virus with neurovirulence for primates much lower than that of elantsev 15-20/3 strain may be obtained by threshold dilutions method on mice. neurovirulence for monkeys of l1-l5 clones of langat tp-21 virus obtained at our laboratory was similar to neurovirulence of a.sabin's type iii vaccinal poliomyelitis virus. attenuated clones of langat virus are stable and retain protective properties in experiments with mouse protection from pathogenic viruses of tick-borne encephal ... | 1994 | 7716907 |
| [a live vaccine against tick-borne encephalitis: the principles of selecting the vaccinal strains]. | the comparative, semiquantitative, pathomorphological study of the neurovirulence of clones of elantsev virus and langat virus tp-21 for intracerebrally infected monkeys has been carried out. the study has revealed that the viruses may be differentiated by their neurovirulence for primates according to the average statistical data on the degree of pathomorphological changes in the central nervous system, but not to maximum lesions in cerebral structures. the level of neurovirulence of yellow fev ... | 1993 | 8067096 |
| inefficient mechanical transmission of langat (tick-borne encephalitis virus complex) virus by blood-feeding mites (acari) to laboratory mice. | one day after feeding on a viremic mouse, tropical rat mites, ornithonyssus bacoti (hirst), transmitted langat (tick-borne encephalitis virus complex) virus to a naive suckling mouse in one of four trials. however, no transmissions to naive mice by o. bacoti were recorded either immediately after the viremic blood meal (0/4 trials) or on days 4-18 (0/20 trials). after feeding on a viremic mouse, chicken mites, dermanyssus gallinae (de geer), failed to transmit langat virus to naive suckling mice ... | 1993 | 8389878 |
| antigenic similarity of central european encephalitis and louping-ill viruses. | twenty isolates of central european encephalitis (cee) virus were compared with 20 isolates of louping-ill (li) virus in indirect immunofluorescence test (iift), using a panel of 17 monoclonal antibodies (moabs) prepared against the prototype li virus. three asian members of the tick-borne encephalitis (tbe) complex were also included in the comparison: turkish sheep encephalitis (tse), russian spring-summer encephalitis (rsse) and langat (lgt) viruses. antigenic relationships of the viruses wer ... | 1995 | 8722293 |
| characterization of langat virus antigenic determinants defined by monoclonal antibodies to e, ns1 and prem and identification of a protective, non-neutralizing prem-specific monoclonal antibody. | hybridomas secreting monoclonal antibodies (mab) to the tick-borne encephalitis (tbe) group virus, langat virus (lgtv), were prepared. of more than 200 mab screened, 19 antibodies, which cross-reacted with the etiologic agent of central european encephalitis, were selected for further characterization. of these mab, 15 were specific for lgtv e glycoprotein, two for the ns1 protein, and three for prem protein. the two ns1-specific mab and two of the e-specific mab reacted with all six of the othe ... | 1996 | 8864202 |
| [an immunomodifier--staphylococcal anatoxin--prevents the development of immunosuppression caused by informational stress in mice]. | the action of information stress for 14 days leads to the development of immunosuppression, which is manifested by the suppression of humoral response to sheep red blood cells (srbc) and the decrease of resistance to langat virus having low pathogenicity. as shown in this investigation, an immunomodifier, purified staphylococcal toxoid (pst), protects experimental animals from the immunosuppressive effect of information stress. after the injection of pst to stress-affected mice in doses of 15 or ... | 1996 | 9027182 |
| attenuation of the langat tick-borne flavivirus by chimerization with mosquito-borne flavivirus dengue type 4. | langat virus (lgt) strain tp21 is the most attenuated of the tick-borne flaviviruses for humans. even though lgt has low-level neurovirulence for humans, it, and its more attenuated egg-passage derivative, strain e5, exhibit significant neurovirulence and neuroinvasiveness in normal mice, albeit less than that associated with tick-borne encephalitis virus (tbev), the most virulent of the tick-borne flaviviruses. we sought to reduce or ablate these viral phenotypes of tp21 and e5 by using a strat ... | 1998 | 9465088 |
| spontaneous and engineered deletions in the 3' noncoding region of tick-borne encephalitis virus: construction of highly attenuated mutants of a flavivirus. | the flavivirus genome is a positive-strand rna molecule containing a single long open reading frame flanked by noncoding regions (ncr) that mediate crucial processes of the viral life cycle. the 3' ncr of tick-borne encephalitis (tbe) virus can be divided into a variable region that is highly heterogeneous in length among strains of tbe virus and in certain cases includes an internal poly(a) tract and a 3'-terminal conserved core element that is believed to fold as a whole into a well-defined se ... | 1998 | 9499069 |
| [stress increases the population of splenic macrophages, permissive for langat virus, in mice]. | as shown in experiments on balb/c mice, stress caused by hypokinesia is associated with a 3- to 8-fold increase in the number of splenic macrophages, permissive to langat virus. no changes in the proportion of t and b lymphocytes in the spleen of the animals occur under the influence of the stress. simultaneously with an increase in the subpopulation of permissive splenic macrophages, the stressed mice have exhibited an increase in sensitivity to intraperitoneal infection with langat virus. | 1998 | 9700885 |
| rapid clearance of simian immunodeficiency virus particles from plasma of rhesus macaques. | perturbation of the equilibrium between human immunodeficiency virus type 1 (hiv-1) and the infected host by administering antiretroviral agents has revealed the rapid turnover of both viral particles and productively infected cells. in this study, we used the infusion of simian immunodeficiency virus (siv) particles into rhesus macaques to obtain a more accurate estimate of viral clearance in vivo. consistently, exogenously infused virions were cleared from plasma with an extremely short half-l ... | 1999 | 9847402 |
| pathogenicity of tick-borne encephalitis virus isolated in hokkaido, japan in mouse model. | the pathogenic characteristics of tick-borne encephalitis (tbe) virus strain (oshima 5-10) isolated from a sentinel dog in hokkaido, japan, was compared by use of a mouse model with several inoculation routes to other strains of tbe virus (the far eastern subtype; sofjin strain and the western subtype; hochosterwitz strain) and tbe complex virus (langat virus; tp-21 strain). the degree of neuroinvasiveness of the strains in mice subcutaneously (s.c.) inoculated was sofjin equaled hochosterwitz w ... | 1999 | 10067683 |
| mapping of functional elements in the stem-anchor region of tick-borne encephalitis virus envelope protein e. | envelope protein e of the flavivirus tick-borne encephalitis virus mediates membrane fusion, and the structure of the n-terminal 80% of this 496-amino-acid-long protein has been shown to differ significantly from that of other viral fusion proteins. the structure of the carboxy-terminal 20%, the stem-anchor region, is not known. it contains sequences that are important for membrane anchoring, interactions with prm (the precursor of membrane protein m) during virion assembly, and low-ph-induced s ... | 1999 | 10364309 |
| replacement of the f and g proteins of respiratory syncytial virus (rsv) subgroup a with those of subgroup b generates chimeric live attenuated rsv subgroup b vaccine candidates. | human respiratory syncytial virus (rsv) exists as two antigenic subgroups, a and b, both of which should be represented in a vaccine. the f and g glycoproteins are the major neutralization and protective antigens, and the g protein in particular is highly divergent between the subgroups. the existing system for reverse genetics is based on the a2 strain of rsv subgroup a, and most efforts to develop a live attenuated rsv vaccine have focused on strain a2 or other subgroup a viruses. in the prese ... | 1999 | 10559287 |
| infectious cdna clones of langat tick-borne flavivirus that differ from their parent in peripheral neurovirulence. | tick-borne flavivirus strain langat tp21 (lgt tp21) recovered from ticks, is naturally attenuated for humans but retains demonstrable neurovirulence and peripheral virulence ("neuroinvasiveness") for mice. previously a mutant, strain e5, less virulent for mice was derived from lgt tp21. multiple attempts to prepare a full-length infectious tp21 cdna from cdna fragments cloned in e. coli were uniformly unsuccessful. a more informative sequence than that obtained from these cloned cdna fragments a ... | 2000 | 10725214 |
| charged residues in the transmembrane domains of hepatitis c virus glycoproteins play a major role in the processing, subcellular localization, and assembly of these envelope proteins. | for most membrane proteins, the transmembrane domain (tmd) is more than just an anchor to the membrane. the tmds of hepatitis c virus (hcv) envelope proteins e1 and e2 are extreme examples of the multifunctionality of such membrane-spanning sequences. indeed, they possess a signal sequence function in their c-terminal half, play a major role in endoplasmic reticulum localization of e1 and e2, and are potentially involved in the assembly of these envelope proteins. these multiple functions are su ... | 2000 | 10729138 |
| replacement of the ectodomains of the hemagglutinin-neuraminidase and fusion glycoproteins of recombinant parainfluenza virus type 3 (piv3) with their counterparts from piv2 yields attenuated piv2 vaccine candidates. | we sought to develop a live attenuated parainfluenza virus type 2 (piv2) vaccine strain for use in infants and young children, using reverse genetic techniques that previously were used to rapidly produce a live attenuated piv1 vaccine candidate. the piv1 vaccine candidate, designated rpiv3-1cp45, was generated by substituting the full-length hn and f proteins of piv1 for those of piv3 in the attenuated cp45 piv3 vaccine candidate (t. tao et al., j. virol. 72:2955-2961, 1998; m. h. skiadopoulos ... | 2000 | 10864657 |
| experimental infection of monkeys with langat virus ii. turnover of circulating virus, 1967. | | 2000 | 10891869 |
| chimeric yellow fever/dengue virus as a candidate dengue vaccine: quantitation of the dengue virus-specific cd8 t-cell response. | we have constructed a chimeric yellow fever/dengue (yf/den) virus, which expresses the premembrane (prm) and envelope (e) genes from den type 2 (den-2) virus in a yf virus (yfv-17d) genetic background. immunization of balb/c mice with this chimeric virus induced a cd8 t-cell response specific for the den-2 virus prm and e proteins. this response protected yf/den virus-immunized mice against lethal dengue encephalitis. control mice immunized with the parental yfv-17d were not protected against de ... | 2000 | 10933719 |
| chimeric langat/dengue viruses protect mice from heterologous challenge with the highly virulent strains of tick-borne encephalitis virus. | langat virus (lgt), a tick-borne flavivirus, is naturally attenuated for humans but it is very virulent in scid mice. in contrast, viable recombinant chimeras of lgt (prem and e genes) and dengue type 4 virus (all other sequences) recovered in mosquito cell culture were completely attenuated in scid mice but still capable of providing protection against lgt. to develop the chimeras into vaccine candidates, we adapted them to replicate efficiently in simian vero cells, a satisfactory substrate fo ... | 2000 | 10936085 |
| langat virus m protein is structurally homologous to prm. | langat (lgt) virus m protein has been generated in a recombinant system. antiserum raised against the lgt virus m protein neutralizes tick-borne encephalitis serocomplex flaviviruses but not mosquito-borne flaviviruses, indicating that the m protein is exposed on the surface of virions. the antiserum recognizes intracellular lgt virus prm/m and binds to prm and m in western blots of whole-cell lysates and purified virus, respectively. these data suggest that the prm and m proteins are structural ... | 2001 | 11264391 |
| biophysical characterization and vector-specific antagonist activity of domain iii of the tick-borne flavivirus envelope protein. | the molecular determinants responsible for flavivirus host cell binding and tissue tropism are largely unknown, although domain iii of the envelope protein has been implicated in these functions. we examined the solution properties and antagonist activity of langat virus domain iii. our results suggest that domain iii adopts a stably folded structure that can mediate binding of tick-borne flaviviruses but not mosquito-borne flaviviruses to their target cells. three clusters of phylogenetically c ... | 2001 | 11264392 |
| infectious cdna clone of attenuated langat tick-borne flavivirus (strain e5) and a 3' deletion mutant constructed from it exhibit decreased neuroinvasiveness in immunodeficient mice. | forty-five years ago a naturally attenuated tick-borne flavivirus, langat (lgt) strain tp21, was recovered from ticks in malaysia. subsequently, it was tested as a live attenuated vaccine for virulent tick-borne encephalitis viruses. in a large clinical trial its attenuation was confirmed but there was evidence of a low level of residual virulence. thirty-five years ago further attenuation of lgt tp21 was achieved by multiple passages in eggs to yield mutant e5. to study the genetic determinants ... | 2001 | 11289811 |