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mosquito-borne arboviruses in arctic america.mosquito-borne arboviruses are prevalent throughout subarctic regions of canada and alaska, principally in the boreal forest extending between latitudes 53 and 66 degrees n, but they have been identified in tundra regions as far north as 70 degrees n. all mosquito-borne agents have been bunyaviruses, comprising principally the snowshoe hare subtype of california encephalitis (ce) virus, but also northway virus. mosquito vectors comprise several aedes species and culiseta inornata, all of which h ...19751602
arbovirus surveillance in six states during 1972.a virus surveillance project was established and maintained during 1972 along 10 major river drainages in six states. mosquitoes, biting flies, and blood specimens from sentinel equines were collected during 83 field trip visits to 141 arthropod collecting sites and 22 sentinel locations from april into december 1972. there were 173,074 mosquitoes tested and 303 arboviruses isolated from 11 of 41 species. from 13,388 biting flies tested, 8 arbovirus isolations were obtained in 1 of 5 species. th ...19767148
ecology of western equine encephalomyelitis in the eastern united states. 197716462
antiviral effect of tebrofen.tebrofen inhibited the replication of western equine encephalomyelitis (wee) virus in multicycle experiments in chick embryo cell cell cultures. the compound did not inhibit the replication of vaccinia and newcastle disease viruses.197718926
ecology of keystone virus, a transovarially maintained arbovirus.our studies in the pocomoke cypress swamp of maryland have shown that key strain of ce is endemic and is carried by the floodwater mosquito a. atlanticus. the virus is transmitted transstadially in nature, as evidenced by our recovery of virus from larvae and males of this species. serologic evidence, both here and elsewhere, indicates that vertebrates are infected with key, but their role in the transmission cycle remains unknown. we have found several animals, for example, the gray squirrel, t ...197520017
chromatographic separations of alphavirus strains by hydroxylapatite.hydroxylapatite column chromatography methods were developed to characterize selected alphavirus populations. different conditions of ph and phosphate molarity were required to obtain satisfactory elution profiles and separations for western equine encephalomyelitis virus strains, compared with eastern equine encephalomyelitis virus and semliki forest virus strains. raising the ph of the buffers effected earlier elutions of all viruses. selection of phosphate gradients with more gentle slopes an ...197720452
occurrence and distribution of western equine encephalomyelitis in florida.research and surveillance programs relating to the occurrence and distribution of western equine encephalomyelitis virus in florida, conducted between 1955 and 1976, suggest that the virus is (1) an endemic arbordae, (2) transmitted in a continuous cycle throughout the year by culiseta melanura mosquitoes, and (3) restricted to fresh water swamps and waterways in central, north, and northwest florida.197823372
mosquito surveys in manitoba during 1975. 19769196
variations in biological properties of geographic strains of western equine encephalomyelitis virus before and after passage in culex tarsalis and culiseta melanura.western equine encephalomyelitis (wee) virus strains from the eastern and western united states were compared using two biological markers: antigenic properties measured by cross complement fixation (cf) tests and the size of plaques produced in vero cell cultures. slight antigenic differences were discernible on a geographic basis, and all of the virus strains from the west produced significantly larger plaques than the eastern isolates. one virus strain from each region was serially passaged i ...197830265
vector competence of colonized culiseta melanura (diptera: culicidae) for western equine encephalomyelitis virus. 197935613
antiviral activity of benzothiazole and benzothiazolinethione derivatives in cell cultures.the virus inhibitory activity of benzothiazole, benzothiazolinethione and naphthothiazole derivatives was tested with vaccinia virus, newcastle disease virus (ndv) and western equine encephalomyelitis (wee) virus in the agar-diffusion plaque-inhibition test. among 58 compounds examined, 5 showed medium activity and selectivity with vaccinia virus. the highest selective effect was found with 3-(2-ethylthio-6-benzothiazolylaminomethyl)-2-benzothiazolinethione. a much lower inhibitory effect was ob ...197941432
a microprecipitation test for rapid detection and identification of venezuelan, eastern and western equine encephalomyelitis viruses.the development of a new diagnostic procedure for the identification of venezvelan, eastern and western equine encephalomyelitis (vee, eee, wee) viruses is described. the procedure utilizes virus precipitation with reference fluorescein-conjugated gamma globulin, followed by cellulose acetate electrophoresis. clinical specimens containing varying concentrations of virus yielded, in primary duck embryo cell culture, sufficient virus for detection within 22 to 44 hours. identification of vee, eee ...197546134
variations in the susceptiblility of field and laboratory populations of culex tarsalis to experimental infection with western equine encephalomyelitis virus.four field populations and four laboratory colonies of culex tarsalis from california were evaluated for their susceptibility to infection with western equine encephalomyelitis (wee) virus by intrathoracic inoculation and by feeding on pledgets soaked with a virus-blood-sucrose mixture. all mosquito strains were uniformly susceptible to infection by intrathoracic inoculation, but 50% infective doses for field and colonized strains varied as much as 1000- to 1500-fold, respectively, by pledget fe ...197658557
interaction of mouse peritoneal macrophages with different arboviruses in vitro [proceedings]. 197666026
[intensification of antibacterial and antiviral nonsusceptibility and of the immune response with an officinal rna preparation].sodium nucleinate increased essentially the insusceptibility of mice to pathogenic escherichia, strain o26, pr. vulgaris, ps. aeruginosa, ser. marcescens, and produced a total stimulating effect on the nonspecific bacterial resistance; analogous stimulating activity was found in the homologous low polymeric rna from the liver. sodium nucleinate intensified the insusceptibility of the animals to the tick-born encephalitis and encephalomyelitis viruses, and increased the antibody-forming cells cou ...1979106911
effects of influenza, mumps, and western equine encephalitis viruses on fetal rhesus monkeys (macaca mulatta).pregnant rhesus monkeys were infected via instillation of influenza, mumps and western equine encephalomyelitis viruses respectively into the amniotic sacs at approximately 90 days gestation to determine if fetal infections would occur. virus was recovered from fetal tissues after seven days in 100% of the exposed animals. thus, the viruses are capable of causing fetal infection. rhesus monkey fetuses were inoculated with influenza, mumps and wee viruses by the direct intracerebral route at appr ...1979117564
fetal mortality and malformations associated with experimental infections of western equine encephalomyelitis vaccine virus in rhesus monkeys (macaca mulatta).pregnant rhesus monkeys were infected via installation of western equine encephalomyelitis (wee) vaccine virus into the amniotic sacs at 50 and 80 days gestation to determine if the resulting infections would produce fetal mortality or fetal malformations, particularly within the central nervous system. of those receiving virus at 50 days gestation, 13 of 18 fetuses were aborted or dead in utero at time of caesarean section; 2 of 18 were malformed (hydrocephalus and polyarthrosis); and 3 of 18 w ...1979117565
viral infection and interferon in cell cultures aged in vitro.cells from leucosis-free chick embryos (skin and muscles), grown in vitro 1 and 7 days with no medium change, are used as a model for young dividing and stationary in vitro aged cells, respectively. aged cultures are advantageous for if induction by cytopathic and noncytopathic viruses. decreased virus production in them is ascribed to a back effect of the early formed if onto the inducing virus. a factor which stimulates viral if interferon induction also in young cultures, is released from age ...1975164104
a serologic survey of pronghorns in alberta and saskatchewan, 1970-1972.to determine the exposure of free-ranging pronghorns (antilocapra americana ord) to selected pathogens, serum samples were obtained from 33 live-trapped animals from southwestern saskatchewan in 1970, and from 26 and 51 animals from southeastern alberta, in 1971 and 1972, respectively. antibodies were found to the agents of parainfluenza 3, bovine virus diarrhea, eastern and western encephalomyelitis, infectious bovine rhinotracheitis and the chlamydial group. no serologic reactors were found to ...1975167203
laboratory diagnosis of western encephalomyelitis. 19769195
equine viral encephalitis.the most important neurotropic viral infections of the horse are the arthropod-borne encephalitides. these include venezuelan encephalitis (ve), eastern encephalitis (ee) and western encephalitis (we), which are found in the americas, and japanese b encephalitis which occurs in the far east. all the viruses cause encephalitis in man. between 1969 and 1972 an epidemic of ve occurred in central america. in 1971 the disease was reported in texas, where it was brought under control by the vaccinatio ...19764301
photochemical inactivation of dna and rna viruses by psoralen derivatives.western equine encephalitis virus, and rna virus, and herpes simplex virus type i, a dna virus, were efficiently inactivated in less than i min by exposure to long-wave ultraviolet light (320 to 380 nm) in the presence of several psoralen derivatives. the psoralen photochemical reaction was chosen for study due to its known specificity for nucleic acids. neither the light nor any of the drugs alone caused appreciable inactivation. the inactivation kinetics and dependence on light intensity and o ...1978211184
buoyant density of some togaviruses in sucrose density gradient and capacity of their haemagglutinin fractions to interact with antibody.the buoyant densities of western equine encephalomyelitis virus (an alphavirus) and tick-borne encephalitis (tbe) virus (a flavivirus) antigens prepared by different methods were studied. sucrose density centrifugation revealed a heterogeneity in the density of the virions. the sedimentation pattern and height of peaks of the haemagglutinating activities and infectivity, other conditions being equal, depended both on the virus species and properties of its strains and on the mode of preparation ...197611662
arbovirus vector ecology studies in mexico during the 1972 venezuelan equine encephalitis outbreak.virus vector studies were conducted in the states of durango, chihuahua, and tamaulipas, mexico, in june and july 1972. apparently only a low level of venzuelan equine encephalitis (vee) virus transmission to equines occured at the time of the study, and the infection was restricted to areas which had not experienced overt activity during the preceding year. the low level of infection was associated with a scarcity of mosquitoes. the ib (epidemic) strain of vee virus was isolated from two pools ...1975235213
a supportive treatment for equine viral encephalitis. 1977244159
correlation between virus-cell receptor properties of alphaviruses in vitro and virulence in vivo.virulent and avirulent clones of venezuelan, western, and eastern equine encephalitis viruses were examined for their in vitro attachment characteristics to the surface of cultured cell monolayers. these attachment characteristics were correlated with in vivo plasma clearance rates and virulence. for the clones investigated, avirulence correlated in vitro with attachment ph optima close to physiologic ph and in vivo with a rapid clearance from plasma. conversely, virulent clones had lower in vit ...1979295182
antiviral effects of double-stranded rna from rice dwarf virus on infection of mice with western equine encephalitis virus.a single administration (1 to 10 mg/kg) of rice dwarf virus rna (rdv-rna) prior to virus challenge reduced the mortality of mice infected with western equine encephalitis (wee) virus. the protective effect of rdv-rna was significantly higher than that of polyinosinic-polycytidylic acid. however, when these rnas were given after virus infection, the protective effect was negligible. the titer of circulating interferon in mice reached a peak about 5 hr after injection of these rnas and remained at ...1977333233
mosquito-virus relationships of american encephalitides. 197824407
complementation between temperature-sensitive mutants isolated from aedes albopictus cells persistently infected with western equine encephalitis virus. 1979425324
inhibition of dna synthesis in bhk cells infected with western equine encephalitis virus. 2. properties of the inhibitory factor of dna polymerase induced in infected cells. 1979228480
studies on immunity to alphaviruses in foals. 1979453684
interaction of alphaviruses with human peripheral leukocytes: in vitro replication of venezuelan equine encephalomyelitis virus in monocyte cultures.human peripheral blood leukocytes (pbl) were examined for their ability to support growth of several group a arboviruses in vitro. cells were refractory to infection with eastern (eee) and western (wee) equine encephalitis viruses, whereas venezuelan equine encephalomyelitis (vee) virus was shown to infect and replicate to a substantially high titer. when pbl were fractionated into purified subpopulations, only the monocytes were susceptible to predictive vee virus infection. lymphocytes treated ...1979468371
prevalence of selected zoonotic diseases in vertebrates from haiti, 1972.vertebrate animals collected in haiti in 1972 were tested for selected zoonotic diseases. no rabies virus or neutralizing (n) antibody was detected in bats (artibeus jamaicensis). however, n antibody against st. louis encephalitis, western equine encephalitis (wee), and eastern equine encephalitis were detected in resident species of birds and wee antibody in bats. no n antibody against venezuelan equine encephalitis was found. the possible introduction by migratory birds and local transmission ...1979480524
evaluation in humans of a new, inactivated vaccine for venezuelan equine encephalitis virus (c-84).a new, formalin-inactivated vaccine for venezuelan equine encephalitis (vee) virus (c-84), prepared from an attenuated vaccine strain of virus (tc-83), was tested in humans. only occasional, mild, local and systemic reactions were noted in 28 volunteers; no meaningful changes in clinical laboratory values occurred. the vaccine augmented preexisting titers of serum neutralizing antibody to vee virus in seropositive recipients of tc-83 vaccine, and it induced high titers of neutralizing antibody i ...1979528788
seroepidemiologic studies in oaxaca, mexico. ii. survey for arbovirus antibody.a serologic survey was conducted in south-western mexico to obtain information on human experience with arbovirus infections. sera were collected from two semitropical areas along the pacific coast of oaxaca state, two mountain areas above 1,700 meters and the interior valley at 1,500 meters. of the 610 sera tested for group a antibody, 4.9 per cent were positive in the hemagglutination-inhibition (hi) test to venezuelan (ve), 11 per cent to eastern, and none to western encephalitis viruses. in ...1979539866
western equine encephalitis with rapid onset of parkinsonism.a patient with confirmed western equine encephalitis had the rapid onset of postencephalitic parkinsonian sequelae. this observation corroborates similar previous but rare reports. response to therapy with levodopa, dopa decarboxylase inhibitor, and trihexyphenidyl was dramatic. however, remission maintained for 12 months without medication suggests that the parkinsonism would have remitted spontaneously. in either case, this has not previously been reported with the western equine togavirus.1977563006
isolation and preliminary characterization of temperature-sensitive mutants of western equine encephalitis virus. 1978622811
study of homologous and heterologous antibody response in california horses vaccinated with attenuated venezuelan equine encephalomyelitis vaccine (strain tc-83).of 359 horses vaccinated with attenuated venezuelan equine encephalomyelitis (vee) vaccine (strain tc-83), 87% developed hemagglutination-inhibition (hi) antibodies to vee virus within 1 month. blood from a subsample of 101 of the 359 horses was obtained over a 1-year period. within 1 month after vaccination, 84% of the 101 horses had developed vee hi antibodies, 87% had developed vee-neutralizing (nt) antibodies, and 78% had developed vee complement-fixing (cf) antibodies. one year after vaccin ...1978637386
selection of a strain of culex tarsalis highly resistant to infection following ingestion of western equine encephalomyelitis virus.after prolonged selection, two hybrid strains of culex tarsalis were evolved that were highly resistant to infection following ingestion of western equine encephalomyelitis virus. these strains were greater than 25,000-fold more resistant than the most susceptible parental strain when fed on viremic chicks. resistance was associated with a mesenteronal barrier since both refractory and parental strains were equally susceptible to infection by intrathoracic inoculation. susceptibility was dominan ...1978646024
efficacy of trivalent inactivated encephalomyelitis virus vaccine in horses.twenty-nine horses were vaccinated with a trivalent (venezuelan, eastern, and western) inactivated equine encephalomyelitis virus vaccine. the vaccine purchased for this study was the only one licensed and commercially available in may, 1975. plaque-neutralizing and hemagglutinin-inhibiting antibodies in response to each of the 3 equine encephalomyelitis viruses were determined after vaccination. horses had rising levels of plaque-neutralizing and hemagglutinin-inhibiting antibodies shortly afte ...1978646197
intranasal exposure of the richardson's ground squirrel to western equine encephalomyelitis virus.adult richardson's ground squirrels were infected with western equine encephalomyelitis virus by intranasal instillation. mortality followed the instillation of a minimum threshold of 4.7 logs of virus while infection was produced by a dosage of 2.3 logs. the incubation period was from four to seven days, being preceded by a viremic phase. signs were depression, ataxia and paralysis of the limbs. highest titres of virus were recovered from the brain and histopathological changes involving the ce ...1978667706
venezuelan equine encephalomyelitis vaccine (strain tc-83): a field study.in 1971, more than 370 horses in south texas were studied with respect to their clinical, virologic, and neutralizing antibody responses to vaccination with venezuelan equine encephalomyelitis (vee) strain tc-83. this study confirms reported findings that the vaccine used in the 1971 epizootic in the lower rio grande valley of texas was safe and efficacious. vaccinal virus viremia titers were generally below the postulated infection threshold of epizootic vectors. in general, reactions to the va ...1978717877
the history of western encephalomyelitis in manitoba. 1976786451
rapid diagnosis of venezuelan equine encephalomyelitis by fluorescence microscopy.goat venezuelan equine encephalomyelitis (vee) antiserum and normal serum were conjugated and evaluated for staining sensitivity and specificity. cross-staining with either eastern or western equine encephalomyelitis virus-infected cells did not occur. the baby hamster kidney (bhk-21) cell line when combined with highly specific vee conjugate detected 100 medium suckling mouse intracerebral lethal doses (suckling mouse ld-50/ic) of the 1b subtype of vee virus per milliliter of equine tissue susp ...1975803352
antibody studies in ponies vaccinated with venezuelan equine encephalomyelitis (strain tc-83) and other alphavirus vaccines.serologic studies in 24 ponies indicated that prevaccination antibodies to venezuelan equine encephalomyelitis (vee) virus (strain tc-83) had no influence on hemagglutination-inhibition (hi) antibody stimulation by western equine encephalomyelitis (wee) or eastern equine encephalomyelits (eee)-wee vaccines. however, studies of the effects of vee neutralizing antibodies on neutralizing antibody stimulation by the heterologous alphavirus vaccines were inconclusive. the vee, wee, and eee antibody r ...1977851275
maturation defect of a temperature-sensitive mutant of western equine encephalitis virus.the defective step of a temperature-sensitive mutant of western equine encephalitis virus, which synthesize viral rna but not mature virus at the restrictive temperature, was studied. cells infected with the mutant virus at the restrictive temperature synthesized the same intracellular viral rna as that in wild type infection. cells infected with the mutant at the restrictive temperature formed three proteins (e1, e2 and c) which migrated to positions identical with those of purified virions and ...1977857772
western equine encephalomyelitis in horses in the northern red river valley, 1975.in mid-july, 1975, western equine encephalomyelitis (wee) virus was isolated from mosquitoes collected in flooded areas of eastern north dakota and western minnesota. inasmuch as clinical manifestations of wee are usually observed in horses before human cases of encephalitis are recognized, surveillance of equine disease was initiated. sixty-one practicing veterinarians from the are under surveillance reported 281 cases of wee in horses from june through september, with peak incidence in late ju ...1977873843
subcutaneous exposure of the richardson's ground squirrel (spermophilus richardsonii sabine) to western equine encephalomyelitis virus.both adult and suckling richardson's ground squirrels (spermophilus richardsonii) were susceptible to subcutaneous exposure with western equine encephalomyelitis (wee) virus, but the virus was more virulent for sucklings than adults. in sucklings, the incubation period was from 4 to 5 days, followed by apparent signs of central nervous system (cns) involvement. death occurred 10 to 13 days postexposure. in adults, infections were inapparent or acute with typical signs of cns involvement similar ...1976933316
preparation and testing of vaccines prepared from the envelopes of venezuelan, eastern, and western equine encephalomyelitis viruses.envelope components were separated from venezuelan, eastern, and western equine encephalomyelitis viruses after treatment of the virions with detergent. vaccines prepared from the envelope component were capable of stimulating mice to produce humoral antibodies. protective efficacy studies were performed using mono-, di-, and trivalent vaccine combinations. these elicited varying degrees of homologous protection, and eastern and venezuelan equine encephalomyelitis envelope products appeared to c ...1976942635
virulence heterogeneity of a predominantly avirulent western equine encephalitis virus population.selective removal of small plaque (sp) western equine encephalitis (wee) virus from a population heterogeneous with respect to virulence and plaque morphology permitted direct detection of a small sub-population of virulent large plaque (lp) wee virus. selective removal of sp-wee virus was achieved by intracardiac (i.c.a.) inoculation of hamsters; plasma obtained 60 min after inoculation was proportionately enriched for lp-wee virus since only the sp-wee virus was cleared. by this method, the pr ...1976956785
sentinel flock monitoring procedures for western encephalomyelitis in manitoba-1975. 1976963653
equine epizootic of western encephalomyelitis in manitoba-1975. 1976963654
an epidemic of western encephalomyelitis in humans-manitoba, 1975. 1976963655
weather conditions affecting mosquito populations in southern manitoba during 1975. 1976963656
western encephalomyelitis in manitoba, 1975: the decision-making process. 1976963657
emergency measures and mosquito control operations during the 1975 western encephalomyelitis outbreak in manitoba. 1976963658
public information on western encephalomyelitis and emergency mosquito control in manitoba, 1975. 1976963659
environmental monitoring of insecticide applications during the emergency mosquito control operation in manitoba, 1975. 1976963660
assessment of the emergency mosquito control operation in manitoba, 1975. 1976963661
analysis of western encephalomyelitis surveillance and control programs in manitoba, 1975. 1976963662
[western encephalomyelitis in manitoba during 1975: summary and recommendations]. 1976963663
the arbovirus problem in canada. 1976963664
variables affecting viral plaque formation in microculture plaque assays using homologous antibody in a liquid overlay.a liquid antibody microculture plaque assay and the variables that govern its effectiveness are described. the assay is based on the principle that low concentrations of homologous antibody can inhibit secondary plaque formation without inhibiting formation of primary plaques. thus, clear plaques that followed a linear dose response were produced. the assay was found to be more rapid, less cumbersome, and less expensive than assays using agar overlays and larger tissue culture plates. it was rep ...1977194918
sensitivities of neurotropic arboviruses to human interferon.the sensitivities of selected neurotropic arboviruses (st. louis encephalitis, western equine encephaltis, and la crosse viruses) to human interferon and polyriboinosinic-polyribocytidylic acid (poly i-poly c) were determined in primary human fetal glial cell cultures. the sensitivities were measured by an end point (inhibition of virus yield). all of the viruses were sensitive to human interferon and poly i-poly c; st. louis encephalitis and western equine encephalitis viruses were inhibited at ...1975171314
inhibition of dna synthesis in bhk cells infected with western equine encephalitis virus. 1. induction of an inhibitory factor of cellular dna polymerase activity. 1979452420
diffusible viral interference during arbovirus plaque formation.a radially diffusing zone of nonspecific interference was observed surrounding plaques of western equine encephalitis virus. the increase in diameters of the zones of interference were linear and more rapid than increases in plaque diameters. these observations raise the possibility that viral-induced interference could account for the diminished growth of western equine encephalitis virus plaques with time or even the initial formation of plaques. in addition, this system could be used as a mod ...1976971948
infectivity of a multiploid-forming mutant of western equine encephalitis virus. 1976978836
effect of cycloheximide on the replication of western equine encephalitis virus. 19761003688
[peculiarities of carbohydrate metabolism in rabbits following prolonged immunization with viral antigens].prolonged, for a period of 5 cycles, immunization of rabbits with tick-borne encephalitis virus, reproduced in the brain of albino mice, caused diabetogenic reaction of the carbohydrate metabolism. it was expressed in hyperglycemia, reduction of hexokinase activity and of glycolysis of hepatic tissue and activation of phosphorylase, glycogenolysis and pentous way of carbohydrate transformation. metabolic changes were accompanied by a reduction of insulin activity of the immunized rabbit serum. a ...19761007747
amount of western equine encephalitis virus inoculated by transmitting culex tarsalis mosquitoes.the amount of western equine encephalitis virus inoculated by infected culex tarsalis mosquitoes is highly variable between individual mosquitoes. the majority (68 per cent) inoculate less than 100 intracerebral three-week-old mouse ld50 at time of feeding and the quanity appears unrelated to temperature or length of incubation following initial infection.19761025639
evaluation of the epidemic potential of western equine encephalitis virus in the northeastern united states. 19761035448
epidemic venezuelan equine encephalitis in north america in 1971: vertebrate field studies.epidemic venezuelan equine encephalitis in north america in 1971: vertebrate field studies. am j epidemiol 101:36-50, 1975.-in june 1971, epidemic venezuelan equine encephalitis (vee) invaded the lower rio grande valley in south texas. the boca chica area of cameron county was selected as a study site to investigate vertebrate involvement in the natural cycle of epidemic vee on the basis of considerable evidence of vee virus activity there in equines, humans, and mosquito vectors. only one vee v ...19751119481
natural infections of richardson's ground squirrels with western equine encephalomyelitis virus, saskatchewan, canada, 1964-1973.a survey (1964-1973) was conducted on naturally occurring western equine encephalomyelitis (wee) virus infections of richardson's ground squirrels (rgs) in agricultural areas of saskatchewan. the survey included both serology and virus isolation attempts on live-trapped wild squirrels. throughout the study, seropostive squirrels were found in the known enzootic regions of the province each summer. the infections rate was high (11.6% of 250) in the epidemic year of 1965 and low (less than 2% o ...19751148947
prevalence of antibodies to arboviruses in egypt. results of a serologic survey among 1,113 university students. 1975173201
morphological and physical properties of a multiploid-forming mutant of western equine encephalitis virus.morphological and physical properties of a multiploid-forming mutant of western equine encephalitis virus were studied. electron micrographs of the infected cells showed that most of mutant virions bud from the plasma or vacuolar membrane as a multiploid particle containing a various number of nucleocapsids enclosed with a defined common envelope. the mutant virions contained three polypeptides which migrated to the position identical with those of wild type on discontinuous acrylamide gels. cel ...19751170339
neutralization kinetics of western equine encephalitis virus by antibody fragments. 19751184110
a field study of persistence of antibodies in california horses vaccinated against western, eastern, and venezuelan equine encephalomyelitis.as a result of the continuing threat of venezuelan equine encephalomyelitis (vee), a study was made to determine if revaccination against vee (tc-83 vaccine) was feasible and if revaccination could be incorporated into other routine vaccination practices. of the horses given annual vaccination with bivalent western equine encephalomyelitis (wee) and eastern equine encephalomyelitis (eee) vaccine, 57% retained detectable serum-neutralizing (sn) antiboyd titers for vee 18 months after the initial ...19751190598
pathogenicity of an attenuated, temperature-sensitive mutant of western equine encephalitis virus induced by a chemical mutagen.to know the pathogenicity of the chemically induced, temperature-sensitive (ts) mutant of western equine encephalitis virus, designated tsng39, the lethality for mice injected with tsng39, virus yield, interferon production, and histological changes in the brains of these mice were examined in parallel with those of mice inoculated with the parent strain (ps). all of the mice injected intracranially with ps died within 3.5 days after injection irrespective of the inoculum size of virus, whereas ...19751193717
trivittatus virus infections in wild mammals and sentinel rabbits in central iowa.a serological survey was conducted in iowa to determine the prevalence rate of california group virus antibodies in sera of several vertebrate species. serum specimens were assayed for infectivity-neutralizing antibody in a microneutralization system with baby hamster kidney cell culture. of 77 sera assayed, 21 (27%) neutralized trivittatus (tvt) virus infectivity. the antibody prevalence rate was highest for eastern cottontail rabbits inasmuch as 46% (10/22) of the serum specimens form this spe ...19751200251
[dependence of immune cytolysis of cells infected with western equine encephalomyelitis virus upon the cell cycle stages].in the first few hours after inoculation of chinese hamster cells with western equine encephalomyelitis virus the mitotic activity of the cells did not change significantly but mitoses stopped mainly in the stage of metaphase and had all signs of pathological mitoses. treatment of the cells for 1 hour with the homologous antiviral immune serum and complement resulted in destruction and death of practically all cells except those in the state of mitosis. in the latter specific fluorescence of vir ...19751241178
arboviral disease--united states, 1991.during 1991, state and local health departments reported 122 cases of human arboviral encephalitis to cdc. more than half (69) of the cases resulted from outbreaks of st. louis encephalitis (sle) in arkansas and texas. in addition, an epizootic of eastern equine encephalitis (eee) extending from the atlantic and gulf coasts into the upper midwest caused sporadic human cases and a substantial loss of livestock. this report summarizes the reported cases of arboviral encephalitis in the united stat ...19921321947
mosquito and arbovirus ecology in southeastern california, 1986-1990.mosquito abundance and western equine encephalomyelitis (wee) and st. louis encephalitis (sle) virus activity were monitored in five valleys in southeastern california from june 1986 through april 1990 to study virus overwintering and possible dissemination from south to north along geographically defined corridors. culex tarsalis coquillett predominated in co2 trap collections and was the only species repeatedly infected with wee and sle viruses. abundance peaked during april-may and august-oct ...19921352557
transmission of western equine encephalomyelitis virus by argentine aedes albifasciatus (diptera: culicidae).aedes albifasciatus (macquart) has been considered a potential vector of western equine encephalitis (wee) virus in argentina because it has been found naturally infected, it is susceptible to infection per os, and its distribution and feeding habits are compatible with those of an epizootic and epidemic vector. ae. albifasciatus females collected in the vicinity of cordoba, argentina, were highly susceptible to wee virus perorally (id50 less than 0.5 vero cell plaque-forming units) when fed on ...19921404265
arbovirus encephalitis-diagnostic considerations. 1976956673
nucleolar fragmentation in cells infected with alphaviruses (39886). 1977909877
solid-phase radioimmunossay for rapid detection and identification of western equine encephalomyelitis virus.a solid-phase radioimmunoassay technique was adapted for the rapid detection and identification of western equine encephalomyelitis virus in clinical specimens.1976824305
[immune mechanisms of resistance in mice to the western equine encephalomyelitis virus].using the immunogenetic method and method of immunomodification of outbred animals, it was established that immune response of humoral or cell-mediated type to wee virus antigens did not play any important role in the survival of intact mice infected with wee virus. under such conditions, it is inexpedient to select immune response modulators. the immune response of predominantly cell-mediated type is a determining factor of resistance to wee virus in mice after immunization started 7 days befor ...19901964514
effects of house sparrow age and arbovirus infection on attraction of mosquitoes.to test the hypothesis that arbovirus infection or advancing age increases the attractiveness of avian hosts to vector mosquitoes, we used an olfactometer that measures the response of mosquitoes to the passive, vertical diffusion of host-related cues. st. louis encephalitis or western equine encephalomyelitis virus infection in house sparrows (passer domesticus (l.], regardless of age, had no detectable effect on culex quinquefasciatus say or cx. tarsalis coquillett attraction, respectively, at ...19901977913
antiviral activities of pyrimidine nucleoside analogues: some structure--activity relationships.seventeen nucleoside derivatives (derived from arabinosylcytosine, resp. cytidine, 5-fluorouracil and uracil) were tested by agar-diffusion plaque-inhibition test for their antiviral activity with herpes simplex, vaccinia, fowl plague, newcastle disease and western equine encephalomyelitis viruses. the highest antiviral activity against dna viruses exhibited arabinosylcytosine, n4-acylarabinosylcytosines, arabinosylthiouracil, cyclocytidine and its 5'-chloroderivative. rna viruses were inhibited ...19901981442
an assessment of the biological capacity of a sacramento valley population of aedes melanimon to vector arboviruses.daily survivorship, duration of the gonotrophic cycle, absolute abundance and season-long relative abundance were estimated for aedes melanimon in the sacramento valley of california in 1987 and 1988 using mark-release-recapture (mrr) techniques and by monitoring changes in the abundance and parity rate of the native population. one objective of these studies was to determine the extent to which a. melanimon was biologically capable of serving as a horizontal arbovirus vector. daily survivorship ...19912042703
multiple intracranial calcifications after western equine encephalitis. 19912067893
peroral susceptibility of aedes albifasciatus and culex pipiens complex mosquitoes (diptera: culicidae) from argentina to western equine encephalitis virus.the transmission cycle of western equine encephalitis (wee) virus in south america is unknown. a wee virus strain was isolated from aedes albifasciatus in argentina during the wee epizootic of 1982-83. also, culex pipiens from argentina was reported to be able to transmit wee virus experimentally, but other results indicate that cx. pipiens from the usa is refractory to this virus. we determined the susceptibility of argentina strains of ae. albifasciatus and culex pipiens complex mosquitos to i ...19902103643
the effect of tilorone hydrochloride on the growth of several animal viruses in tissue cultures.tilorone hydrochloride, at a concentration of 10 mug/ml inhibits the growth of herpes simplex virus type 1 in bs-c-1 cells. the growth of vaccinia virus in bs-c-1 cells is partially inhibited; however, six viruses containing rna, including four members of the togavirus group grown in chick fibroblasts, are not affected by the drug. the inhibition of the growth of herpes virus by tilorone hydrochloride is greater when the multiplicity of infection is lower than 1 p.f.u/cell and when the drug is a ...1976177724
temporal variations in the susceptibility of a semi-isolated population of culex tarsalis to peroral infection with western equine encephalomyelitis and st. louis encephalitis viruses.a semi-isolated population of culex tarsalis in kern county, ca was found to vary significantly in its seasonal and yearly susceptibility to peroral infection with western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses during the breeding seasons of 1975-1981. female cohorts of the population were significantly more resistant to wee virus from 1975 through 1977 than from 1978 through 1981. on the average, females were 40 times more susceptible to wee virus during may tha ...19902160200
diel changes in adult mosquito microhabitat temperatures and their relationship to the extrinsic incubation of arboviruses in mosquitoes in kern county, california.microhabitat temperatures experienced by nocturnally active culex tarsalis coquillett mosquitoes were measured in the southern san joaquin valley of california. temperatures of the diurnal resting shelter and nocturnal activity air space were measured by digital recorder at three cx. tarsalis habitats in kern county. temperatures measured by digital recorders agreed well with temperatures recorded concurrently at nearby california irrigation management and inspection system weather stations. mon ...19902167374
persistence of mosquito-borne viruses in kern county, california, 1983-1988.the persistence of arboviruses was studied from 1983 to 1988 in mixed agriculture, marsh, riparian, and foothill habitats in kern county, ca. western equine encephalomyelitis (wee) virus was isolated frequently during 1983 from culex tarsalis and aedes melanimon and was detected by the seroconversion of sentinel chickens. wee virus then disappeared, even though vector competence studies during 1984-1986 showed that cx. tarsalis was able to transmit wee virus. st. louis encephalitis (sle) virus w ...19902240370
[insulin activity of blood serum of rabbits immunized with tick-borne encephalitis- and western-equine-encephalomyelitis viruses].administration of brain suspension of intact albino mice during the 1st, 3rd and 7th days after a single, double and prolonged (5-cycle) immunization of rabbits produced no significant changes in the functional condition of the insular apparatus. a single use in the capacity of an antigen of the brain tissue containing the tick-borne encephalitis or western horse encephalomyelitis viruses also led to no marked shifts in the blood serum insulin activity. in reimmunization with the virus-containin ...1978665023
binding of western equine encephalomyelitis virus to brush border fragments isolated from mesenteronal epithelial cells of mosquitoes.brush border fragments (bbf) were isolated from mesenteronal epithelial cells of mosquitoes that are either susceptible (ws culex tarsalis) or refractory (wr cx. tarsalis; culex pipiens) to peroral infection by western equine encephalomyelitis (wee) virus. the isolated bbf were combined with radiolabeled wee virus in a binding assay to compare the amount of virus bound by bbf from susceptible and refractory mosquitoes. bbf and wee virus were mixed in a microcentrifuge tube, incubated for 1 h and ...19902291333
detection of arbovirus antibodies in avian sera by the complement fixation-inhibition test.the complement fixation-inhibition (cfi) test was described for the detection of antibodies to arboviruses in bird sera. the cfi antibody present in bird sera inhibited the standard complement-fixation reaction of a reference complement-fixing antigen-antibody pair. using reference antigens (st. louis encephalitis, eastern equine encephalomyelitis, western equine encephalomyelitis, and yellow fever) prepared from infected mouse brains and reference antisera prepared in rabbits or horses, reprodu ...1979464371
properties of monospecific antibodies to the glycoprotein of western equine encephalitis virus.monospecific (msp-) antisera against e1 and e2 glycoproteins of western equine encephalitis (wee) virus were prepared and examined for binding activities to whole virions, hemagglutination-inhibition (hi), neutralization (nt) and protection. both anti-e1 and anti-e2 msp-abs protected mice against wee virus challenge. a competition experiment with monoclonal antibodies showed that these msp-antisera appear to lack the antibody population for some epitopes involved in viral neutralization.19862425229
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