| development of a species-diagnostic polymerase chain reaction assay for the identification of culex vectors of st. louis encephalitis virus based on interspecies sequence variation in ribosomal dna spacers. | culex pipiens complex mosquitoes (cx. p. pipiens and cx. p. quinquefasciatus) are among the principal vectors of st. louis encephalitis (sle) virus in the eastern united states; cx. restuans and cx. salinarius play secondary roles in the transmission and maintenance of the virus cycle. accurate identification of these three species in field collections is required for epidemiologic studies of sle virus transmission. we have developed a polymerase chain reaction (pcr) assay for this purpose. spec ... | 1995 | 7625528 |
| nonvascular delivery of st. louis encephalitis and venezuelan equine encephalitis viruses by infected mosquitoes (diptera: culicidae) feeding on a vertebrate host. | we determined whether mosquitoes infected with the viruses st. louis encephalitis (sle) or venezuelan equine encephalitis inoculate virus extravascularly or directly into the vascular system. infected mosquitoes fed on the distal 3rd of the tails of suckling mice. significantly more mice whose tails were amputated at the midpoint within 10 min of mosquito feeding survived than did siblings whose tails remained intact. even when tails were amputated 1-6 h after sle virus-infected mosquitoes fed, ... | 1995 | 7650720 |
| vector competence of aedes albopictus from pine bluff, arkansas, for a st. louis encephalitis virus strain isolated during the 1991 epidemic. | the vector competence of aedes albopictus from pine bluff, ar, was assessed for a st. louis encephalitis (sle) virus strain isolated during the 1991 epidemic. aedes albopictus were fed on hamsters with viremia levels of 10(4.6)-10(4.9) vero cell plaque-forming units (pfu)/ml. at 7 and 15 days postbloodfeeding, transmission trials were conducted using individual suckling mice. three of 313 ae. albopictus were determined to be infected with sle virus with titers of 10(6.3)-10(7.0) pfu/mosquito. at ... | 1994 | 7707054 |
| comparison of chickens and pheasants as sentinels for eastern equine encephalitis and st. louis encephalitis viruses in florida. | pheasants and chickens were compared as sentinels for monitoring the transmission of arboviruses of public health significance in florida during 1991-93. results suggest that pheasants are better sentinels for eastern equine encephalitis (eee) virus. they detected virus transmission 3-6 weeks earlier in epizootic years, 2-4 times more frequently during the season, and twice as many birds within a flock seroconverted during a given week. pheasants detected virus transmission at 2 sites during 2 i ... | 1994 | 7707062 |
| viremia and serological responses in adult chickens infected with western equine encephalomyelitis and st. louis encephalitis viruses. | adult hens, similar to those used for arbovirus surveillance, were experimentally infected with western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses to describe the viremia response, to compare serological testing methods, and to evaluate a new method of collecting whole blood onto filter paper strips from lancet pricks of the chicken comb. young (19 weeks), but not old (38 weeks), hens developed a low-titer, transient viremia for a 1-day period. immunoglobulin g (igg) ... | 1994 | 7707063 |
| arboviruses in water birds (ciconiiformes, pelecaniformes) from florida. | sera from 360 ciconiform and pelecaniform birds collected in florida (usa) from 1974 to 1990 were tested for serum neutralizing (sn) antibodies to eastern equine encephalitis (eee), st. louis encephalitis (sle), and everglades (eve) viruses. serum neutralizing antibodies to eee virus were detected in 2%, to sle virus in 7%, and to eve virus in none of the samples. pelecaniform birds (16%) had a higher antibody prevalence (p < 0.02) for sle virus than did ciconiform birds (5%). virus could not be ... | 1994 | 8028106 |
| potential effect of global warming on mosquito-borne arboviruses. | if global warming occurs in california, daily mean temperatures may increase by 3 to 5 degrees c, precipitation patterns will change, and sea level may rise 1 m. studies were done on effect of temperature changes on survival of culex tarsalis coquillett, the primary vector of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses, in two regions where temperatures differed by 5 degrees c. daily mortality of adult vectors increased by 1% for each 1 degree c increase in te ... | 1994 | 8057305 |
| [the relationship between mosquito vectors and aquatic birds in the potential transmission of 2 arboviruses]. | the authors studied for two years the role of the chicks of aquatic birds in the arboviral cycles in coastal lagoons in central panama in order to determine the relation between culex (melanoconion) ocossa and mansonia (mansonia) dyari mosquitoes in the transmission and dissemination of the viruses of saint louis encephalitis (sle) and venezuelan equine encephalitis (vee). mosquitoes were captured every fifteen days on two consecutive nights to isolate the virus, using light traps (cdc) and bait ... | 1993 | 8101009 |
| epidemiologic aspects of a st. louis encephalitis outbreak in fort walton beach, florida in 1980. | from july 10 through august 4, 1980, five cases of st. louis encephalitis (sle) occurred in and near fort walton beach on the gulf coast of northwest florida. these were the first cases of sle ever reported from the florida panhandle. to determine the extent of sle infection in the community, sera (n = 968) were collected from patients at the local hospital and county public health unit and tested for sle virus antibody. the sle attack rate was highest in a centrally located impoverished census ... | 1994 | 8147497 |
| st louis encephalitis virus establishes a productive, cytopathic and persistent infection of sf9 cells. | the sf9 cell line, commonly used for gene expression by recombinant baculovirus, has been productively infected by st louis encephalitis (sle) virus, a flavivirus. sle viral infection produced a c.p.e. in the sf9 cells characterized by giant cells and the presence of 10-fold fewer cells in the infected cultures after the first week of infection compared with uninoculated control cultures. infected sf9 cells expressed sle viral antigens, and intracellular virus particles were observed by electron ... | 1993 | 8345362 |
| epidemiologic aspects of a st. louis encephalitis epidemic in jefferson county arkansas, 1991. | in 1991, the first epidemic of st. louis encephalitis (sle) ever reported in arkansas resulted in 25 cases in pine bluff (attack rate: 44 per 100,000; 95% confidence interval [ci] 28-65). to identify risk factors for sle viral infection and risk factors for neuroinvasive illness, we conducted a community-based, cross-sectional study of noninfected and asymptomatically infected persons and a case-control study of asymptomatically and symptomatically infected persons. the sle viral infection rate ... | 1993 | 8352389 |
| entomologic investigations of an epidemic of st. louis encephalitis in pine bluff, arkansas, 1991. | an epidemic of st. louis encephalitis (sle) occurred in jefferson county, arkansas during july-august 1991. at least 26 human cases were involved, with 25 cases in the town of pine bluff. twelve isolates of sle virus were obtained from mosquitoes collected in pine bluff between august 13 and 24: 11 from pools of culex pipiens quinquefasciatus, resulting in a minimum infection rate of 1.6 per 1,000 (n = 6,768) for this subspecies, and one isolate from a pool of 22 mosquitoes identified as cx. (cu ... | 1993 | 8352390 |
| avian hosts of st. louis encephalitis virus in pine bluff, arkansas, 1991. | an investigation of the extent of st. louis encephalitis (sle) virus activity in the avian population in pine bluff, arkansas was conducted from august 30, 1991 through september 5, 1991, following an sle epidemic that resulted in 25 human cases. a total of 363 birds of 33 species were captured with ground-level mist nets at four sites along the northern edge of the city. no viruses were isolated from the serum of these birds, but 91 birds (25%) of 11 species had detectable neutralizing antibody ... | 1993 | 8352391 |
| effect of temperature on the transmission of western equine encephalomyelitis and st. louis encephalitis viruses by culex tarsalis (diptera: culicidae). | the extrinsic incubation rate (inverse of the time in days from infection to median transmission) of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses by laboratory strains of culex tarsalis coquillett increased as a linear function of incubation temperatures from 10 to 30 degrees c. the estimated temperatures for zero transmission thresholds (intercept of the x axis) were 10.9 and 14.9 degrees c, and the number of degree days above these thresholds required for med ... | 1993 | 8433322 |
| arbovirus surveillance in northern colorado, 1987 and 1991. | arbovirus surveillance was conducted during an epizootic of western equine encephalitis (wee) during 1987 and during a nonepizootic year, 1991, in the same area in northern colorado. mosquitoes were collected in larimer county, co, during weeks 33-37 (10 august to 7 september) in 1987 and during weeks 26-35 (24 june to 26 august) in 1991. in total, 13,099 mosquitoes in 694 pools collected during 1987 and 8,672 mosquitoes in 242 pools collected during 1991 were tested for virus. wee virus was iso ... | 1993 | 8433334 |
| search for viral nucleic acid sequences in brain tissues of patients with schizophrenia using nested polymerase chain reaction. | we used polymerase chain reaction to search for nucleic acid sequences of several viruses in dna and rna extracted from brain tissues of schizophrenic and control subjects. | 1996 | 8540775 |
| mosquito productivity and surveillance for st. louis encephalitis virus in chicago during 1993. | the city of chicago's department of health monitors weekly deposition of egg rafts of culex species, prevalence of st. louis encephalitis (sle) virus-specific antibodies in feral birds, and prevalence of the virus in mosquito pools. the total number of culex egg rafts collected in 1993 (4,623) was 2-fold greater than for the 1992 mosquito season. virtually all of the early summer egg rafts were identified as culex restuans. after the week of july 18, culex pipiens accounted for 20-70% of the tot ... | 1995 | 8551297 |
| immunisation with dna polynucleotides protects mice against lethal challenge with st. louis encephalitis virus. | in vivo transfection by intramuscular injection with plasmids expressing the immunogenic proteins of microbial pathogens has considerable potential as a vaccination strategy against many pathogens of both man and animals. here we report that weanling mice given a single intramuscular injection of 50 micrograms of a plasmid, psle1 expressing the st. louis encephalitis virus (sle) prm/e protein under the control of the cytomegalovirus immediate early protein promoter produced sle-specific antibody ... | 1996 | 8645110 |
| seasonal variation in the vector competence of culex tarsalis (diptera:culicidae) from the coachella valley of california for western equine encephalomyelitis and st. louis encephalitis viruses. | the vector competence of culex tarsalis coquillett from the coachella valley of california for western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses was monitored monthly from february to november 1993. the concentration of wee virus required to infect 50% of the females increased during summer coincidentally with ambient temperature and was highest during july. transmission rates of wee virus were high during march, low during may-june, and high again during july-septe ... | 1996 | 8667391 |
| arbovirus titer variation in field-collected mosquitoes. | patterns in the distribution of titers in arbovirus-positive mosquito pools were examined. virus isolation records from the division of vector-borne infectious diseases, centers for disease control and prevention, from 1974 through 1993 were used to estimate virus titers in field-collected pools. pools were classified as either low titer (< or = 3.0 log10 plaque-forming units [pfu]/ml) or high titer (> 3.0 log10 pfu/ml). the proportion of virus-positive pools that had high titers varied among th ... | 1996 | 8827588 |
| antibodies to arthropod-borne encephalitis viruses in small mammals from southern florida. | from 1987 through 1991, blood samples were collected from 10 species of small mammals in indian river country, florida (usa). sera from 1,347 animals were analyzed for hemagglutination-inhibition (hi) antibody to st. louis encephalitis (sle) and eastern equine encephalitis (eee) viruses. of these, 75 (5.6%) were positive for hi antibody to sle virus and 121 (9.0%) were positive for eee antibody. sera from five mammalian species were tested for neutralizing (nt) antibody to sle, eee, highlands j ... | 1996 | 8827668 |
| eastern equine encephalitis transmission to emus (dromaius novaehollandiae) in volusia county, florida: 1992 through 1994. | from may 1992 through october 1994, sera were collected from 204 domestic emus (dromaius novaehollandiae) at a ranch in volusia county, fl, and tested for antibody evidence of arboviral infection. hemagglutination-inhibition (hi) and neutralizing (nt) antibodies to eastern equine encephalitis (eee) virus were identified in sera collected during each year. in addition, hi and nt antibodies to st. louis encephalitis virus were detected in 3 naturally infected emus. isolations of eee virus were mad ... | 1996 | 8887222 |
| restriction analysis of the ribosomal dna internal transcribed spacer region of culex restuans and mosquitoes in the culex pipiens complex. | members of the culex pipiens linn. complex in the eastern, southern, and central united states are the primary vectors of st. louis encephalitis virus. although species and subspecies in the complex can be identified as 4th-instar larvae and by characters on the male genitalia, adult females cannot be identified accurately. in this study a ribosomal dna (rdna) segment that includes the internal transcribed spacer region (its) was amplified from culex pipiens pipiens linn., culex quinquefasciatus ... | 1996 | 8887228 |
| evaluation of a reverse transcriptase-polymerase chain reaction assay for detecting st. louis encephalitis virus using field-collected mosquitoes (diptera: culicidae). | a reverse transcriptase-polymerase chain reaction assay (rt-pcr) was compared with a tissue culture assay (tc) and an enzyme immunoassay (eia) to detect st. louis encephalitis virus (slev) in mosquito pools. overall, 1,725 mosquito pools with a low viral prevalence (3.3%-5.0%) were tested. the comparison of the eia to tc showed that the eia was 0.947 sensitive, 0.988 specific, and 0.987 accurate. comparison of rt-pcr to tc showed that the rt-pcr was 0.947 sensitive, 0.980 specific, and 0.979 acc ... | 1996 | 8906915 |
| transmission patterns of st. louis encephalitis and eastern equine encephalitis viruses in florida: 1978-1993. | sentinel chickens were maintained at field sites in 40 florida counties for varying periods between 1978 and 1993. for each county, the total number of st. louis encephalitis virus (sle) or eastern equine encephalitis (eee) virus seroconversions were divided by the number of chickens exposed to calculate a mean annual seroconversion rate. these rates were used to evaluate the annual and geographical distributions of these viruses within florida. for sle, the rates in counties that reported human ... | 1996 | 8906917 |
| prevalence of antibodies to mosquito-borne encephalitis viruses in residents of the coachella valley, california. | sera from 19 (2.6%) and 118 (16.4%) of 719 outpatients attending clinics in the southeastern coachella valley, california during 1993 and 1994 exhibited igg antibodies to western equine encephalomyelitis and st. louis encephalitis (sle) viruses, respectively, using enzyme immunoassays. however, only seven (1.0%) and 36 (5.0%) outpatients were positive by plaque-reduction neutralization tests (prnts), and seven (1.0%) and 84 (11.7%) outpatients were positive by sera hemagglutination inhibition as ... | 1996 | 9025696 |
| a simple device for the exposure of animals to infectious microorganisms by the airborne route. | in order to evaluate prophylaxis and therapy for individuals infected with pathogens by the airborne route, we have designed and built a simple apparatus in which small laboratory animals may be exposed to aerosols of infectious microorganisms. animals are kept in a chamber closed by a hepa filter and exposed to the pathogen aerosolized using a collison nebulizer. air in the exposure chamber may be sampled to show that the infectious agent is present but the dose of agent must be expressed as 50 ... | 1997 | 9042037 |
| landscape ecology of arboviruses in southeastern california: temporal and spatial patterns of enzootic activity in imperial valley, 1991-1994. | western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses were detected in the imperial valley during the summers of 1991-1994 by isolation from the primary vector, culex tarsalis coquillett, and by the seroconversion of sentinel chickens. enzootic transmission consistently was not detected first each year at sampling sites near specific landscape features such as a heron rookery and other riparian habitats along the new river, sites along the mexican border, or saline and ... | 1997 | 9103761 |
| development of a polymerase chain reaction assay for differentiation between culex pipiens pipiens and cx. p. quinquefasciatus (diptera: culicidae) in north america based on genomic differences identified by subtractive hybridization. | culex pipiens is a complex of mosquitoes that are involved in the transmission of pathogens, including st. louis encephalitis virus in north america. the 2 major taxa in the complex, cx. p. pipiens and cx. p. quinquefasciatus, are nearly identical morphologically, making identification of field-collected specimens difficult, and attempts at differentiation based on biochemical and molecular techniques have been unsuccessful. we report here the use of genomic subtractive hybridization to identify ... | 1997 | 9379458 |
| prevalence of antibodies to western equine encephalomyelitis and st. louis encephalitis viruses in residents of california exposed to sporadic and consistent enzootic transmission. | sera from outpatients attending county health department clinics in areas of california with consistent (imperial valley) and sporadic (sacramento valley) enzootic transmission of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses exhibited neutralizing antibody prevalence rates of 1.3% (n = 690) and 0.5% (n = 1,066) for wee and 11.0% and 0.8% for sle, respectively. seroprevalence for sle virus in imperial county increased as a function of both age and years of resid ... | 1997 | 9392590 |
| effects of water quality on the vector competence of culex tarsalis (diptera: culicidae) for western equine encephalomyelitis (togaviridae) and st. louis encephalitis (flaviviridae) viruses. | the effects of water quality during immature development on the vector competence of adult female culex tarsalis coquillett for western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses was evaluated during 6 field and 4 laboratory experiments. immatures of the bakersfield field station laboratory strain and the f1 progeny of field-collected females were reared in the field or laboratory and then infected by feeding on pledgets, after which remnants (head, thorax, abdomen), ... | 1997 | 9439117 |
| neutralizing antibodies protect against lethal flavivirus challenge but allow for the development of active humoral immunity to a nonstructural virus protein. | antibody-mediated neutralization of viruses has been extensively studied in vitro, but the precise mechanisms that account for antibody-mediated protection against viral infection in vivo still remain largely uncharacterized. the two points under discussion are antibodies conferring sterilizing immunity by neutralizing the virus inoculum or protection against the development of disease without complete inhibition of virus replication. for tick-borne encephalitis virus (tbev), a flavivirus, trans ... | 1998 | 9525632 |
| seroprevalence of selected disease agents from free-ranging black bears in florida. | sera obtained from 66 free-ranging florida black bears (ursus americanus floridanus) from three geographic areas of florida (usa) between november 1993 and august 1995 were tested for antibodies to 13 disease agents. antibody prevalences were 3 positive of 37 tested (8%) coxiella burnetti, 37 of 66 (56%) toxoplasma gondii, 3 of 61 (5%) bluetongue virus/epizootic hemorrhagic disease virus (btv/ehdv), 4 of 66 (6%) canine adenovirus-type 1, 5 of 66 (8%) canine distemper virus (cdv), 10 of 62 (16%) ... | 1998 | 9706572 |
| surveillance for arthropod-borne viral activity in nebraska, 1994-1995. | a 2-yr arbovirus surveillance program was established in nebraska following the midwest flood of 1993. cdc light traps were used to collect mosquitoes at 11 localities throughout nebraska. in 1994, we collected 685,582 mosquitoes, and we tested 1,359 pools of culex mosquitoes for arbovirus infection, with st. louis encephalitis virus isolated from 2 pools collected in scotts bluff county in western nebraska. in 1995, 1,163,741 mosquitoes were collected and 2,788 pools tested, with 36 positive fo ... | 1998 | 9775605 |
| new mouse model for dengue virus vaccine testing. | several dengue (den) virus vaccines are in development; however, the lack of a reliable small animal model in which to test them is a major obstacle. because evidence suggests that interferon (ifn) is involved in the human anti-den virus response, we tested mice deficient in their ifn functions as potential models. intraperitoneally administered mouse-adapted den 2 virus was uniformly lethal in ag129 mice (which lack alpha/beta ifn and gamma ifn receptor genes), regardless of age. immunized mice ... | 1999 | 9847388 |
| interferon-alpha protects mice against lethal infection with st louis encephalitis virus delivered by the aerosol and subcutaneous routes. | in common with other flaviviruses, there is no specific therapy for st louis encephalitis (sle) virus infections. a number of cases have occurred where infection may have been acquired by the aerosol route in laboratory accidents. the recombinant human interferon hybrids ifn-alpha a/d (roche laboratories) and ifn-alpha b/d (ciba-geigy) have activity in murine models. given for several days around the time of exposure to the virus or shortly after, these compounds reduce the mortality from sle vi ... | 1999 | 10321579 |
| use of base excision sequence scanning for detection of genetic variations in st. louis encephalitis virus isolates. | twenty-two isolates of st. louis encephalitis (sle) virus of various geographical origins (brazil, argentina, panama, texas, missouri, maryland, california, and florida) were examined for genetic variation by the base excision sequence scanning (bess t-scan) method. a fragment was amplified in the envelope gene with the forward primer labeled in the pcr. the bess t-scan method determined different clusters according to the profiles generated for the isolates and successfully grouped the isolates ... | 1999 | 10325350 |
| mosquito-borne viruses in western europe: a review. | several mosquito-borne arboviruses belonging to the genera alphavirus, flavivirus, and bunyavirus have been reported to occur in mosquitoes and to infect humans and other vertebrates in western europe. these zoonotic viruses circulate in nature either in an aedes-mammal, anopheles-mammal, or culex-bird transmission cycle. infected humans normally do not contribute to the virus circulation. west nile virus (flavivirus) caused an outbreak of fever, malaise, pain in eyes and muscles, and headache a ... | 1999 | 10436876 |
| identification of genetic variation among st. louis encephalitis virus isolates, using single-strand conformation polymorphism analysis. | a single-strand conformation polymorphism (sscp) technique was developed for identification of genetic variation among 26 isolates of st. louis encephalitis (sle) virus. a 750-bp portion of the envelope gene was amplified by reverse transcription-polymerase chain reaction (rt-pcr) and the products analyzed by sscp. sscp reliably identified genetic variation among the isolates from the us, central and south america. closely related isolates from a smaller geographic area (panama) were also distin ... | 1999 | 10471026 |
| electron microscopic diagnosis of human flavivirus encephalitis: use of confocal microscopy as an aid. | the distinction between intracranial viral infections and inflammatory conditions requiring immunosuppression is important. although specific laboratory reagents are readily available for some viruses, diagnosis of arbovirus infection is more difficult. transmission electron microscopy (tem) theoretically allows identification of viral particles independent of reagent availability, but it has limited sensitivity. we report two cases of human flavivirus encephalitis diagnosed by tem. laser scanni ... | 1999 | 10524522 |
| update: west nile-like viral encephalitis--new york, 1999. | the outbreak of human arboviral encephalitis attributable to a mosquito-transmitted west nile-like virus (wnlv) continues to wane in the northeast. as of october 5, the number of laboratory-positive cases had increased to 50 (27 confirmed and 23 probable), including five deaths. the increase in cases is mainly a result of completed retesting with west nile virus antigen of specimens previously tested with the related st. louis encephalitis virus antigen and to intensive retrospective case findin ... | 1999 | 10550041 |
| groups race to sequence and identify new york virus. | | 1999 | 10577182 |
| phylogeny of the genus flavivirus using complete coding sequences of arthropod-borne viruses and viruses with no known vector. | attempts to define the evolutionary relationships and origins of viruses in the genus flavivirus are hampered by the lack of genetic information particularly amongst the non-vectored flaviviruses. using a novel protocol for sequence determination, the first complete coding sequence of st louis encephalitis virus and those of two representative non-vectored flaviviruses, rio bravo (isolated from bat) and apoi (isolated from rodent), are reported. the encoded polyproteins of rio bravo and apoi vir ... | 2000 | 10675416 |
| role of peridomestic birds in the transmission of st. louis encephalitis virus in southern california. | in response to the 1984 st. louis encephalitis (sle) epidemic in the los angeles basin of southern california (usa), an investigative program was initiated to evaluate the interactive components of the sle virus transmission cycle. from 1987 through 1996 (10 yr), 52,589 birds were bled and their sera tested for sle and western equine encephalomyelitis (wee) virus antibodies by the hemagglutination inhibition (hai) test. eighty-three percent of the birds tested were house finches (carpodacus mexi ... | 2000 | 10682741 |
| method of infection does not alter response of chicks and house finches to western equine encephalomyelitis and st. louis encephalitis viruses. | the effects of method of infection and virus dose on the viremia and antibody responses of 1-wk-old chicks and after-hatching-year house finches to infection with western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses were studied under laboratory conditions. using a capillary tube technique, females from 2 strains of culex tarsalis coquillett mosquitoes were estimated to expectorate from 1.0 to 1.7 log10 plaque forming units (pfu) of wee and from 1.9 to 2.2 log10 pfu of ... | 2000 | 10730496 |
| response of house finches to infection with sympatric and allopatric strains of western equine encephalomyelitis and st. louis encephalitis viruses from california. | adult house finches from kern county were inoculated subcutaneously with recent sympatric and allopatric isolates of western equine encephalomyelitis and st. louis encephalitis (sle) viruses made from culex tarsalis coquillett collected in kern county and coachella valley, ca, respectively. virulence, as measured by the amplitude of the viremia response during days 1 and 2 postinfection, varied significantly among strains, but independently of geographic origin. the intensity of the immune respo ... | 2000 | 10730497 |
| relationships among weather, mosquito abundance, and encephalitis virus activity in california: kern county 1990-98. | the summer abundance of culex tarsalis in kern county, california, during 1990-98 was related quantitatively to rainfall, snow depth and water content, and runoff of the kern river. total monthly rain that fell during winter, lagged by 4-6 months, explained only 13% of the variability in the number of host-seeking females collected per trap night per month during summer. in contrast, regression analysis showed that river runoff 1 month earlier explained 67% of the variability in mosquito abundan ... | 2000 | 10757487 |
| detection of anti-arboviral immunoglobulin g by using a monoclonal antibody-based capture enzyme-linked immunosorbent assay. | monoclonal antibody (mab)-based capture enzyme-linked immunosorbent assays (elisas) for the detection of anti-arboviral immunoglobulin g (igg elisas) were developed for a comprehensive array of medically important arboviruses from the alphavirus, flavivirus, and bunyavirus genera. tests were optimized and standardized so that maximum homology could be maintained among working parameters for the different viral agents, enabling a wide range of viruses to be easily tested for at one time. mabs wer ... | 2000 | 10790108 |
| pathology of fatal west nile virus infections in native and exotic birds during the 1999 outbreak in new york city, new york. | west nile fever caused fatal disease in humans, horses, and birds in the northeastern united states during 1999. we studied birds from two wildlife facilities in new york city, new york, that died or were euthanatized and were suspected to have west nile virus infections. using standard histologic and ultrastructural methods, virus isolation, immunohistochemistry, in situ hybridization and reverse-transcriptase polymerase chain reaction, we identified west nile virus as the cause of clinical dis ... | 2000 | 10810985 |
| migratory birds and spread of west nile virus in the western hemisphere. | west nile virus, an old world flavivirus related to st. louis encephalitis virus, was first recorded in the new world during august 1999 in the borough of queens, new york city. through october 1999, 62 patients, 7 of whom died, had confirmed infections with the virus. ornithophilic mosquitoes are the principal vectors of west nile virus in the old world, and birds of several species, chiefly migrants, appear to be the major introductory or amplifying hosts. if transovarial transmission or survi ... | 2000 | 10905964 |
| patterns of avian seroprevalence to western equine encephalomyelitis and saint louis encephalitis viruses in california, usa. | temporal and spatial changes in the enzootic activity of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses were monitored at representative wetland study sites in the coachella, san joaquin, and sacramento valleys of california from 1996 to 1998 using three methods: (1) virus isolation from pools of 50 host-seeking culex tarsalis coquillett females, (2) seroconversions in flocks of 10 sentinel chickens, and (3) seroprevalence in wild birds collected by mist nets and ... | 2000 | 10916291 |
| frequency of saint louis encephalitis virus in humans from florida, usa: 1990-1999. | four general frequencies of human st. louis encephalitis (sle) virus (epidemic, focal, sporadic, and no transmission) occurred in florida between 1990 and 1999. an epidemic with 226 clinical cases and 11 deaths was reported from 28 florida counties between july 1990 and january 1991. during the autumn of 1993, a focal outbreak was reported from lee (5 cases) and collier (3) counties in southwest florida. during the autumn of 1997, sporadic transmission to nine humans was reported from five flori ... | 2000 | 10916306 |
| [serological survey on arbovirus infection in residents of an ecological reserve]. | serological inquires conducted in the ribeira valley, s. paulo state, brazil, showed an intense circulation of pathogenic arboviruses in the region. the goal was to verify the prevalence of arboviral infections in people living at the local ecological, and its potential association with these population' individual and familiar characteristics. | 2000 | 10920445 |
| epidemiological features of and public health response to a st. louis encephalitis epidemic in florida, 1990-1. | a st. louis encephalitis (sle) epidemic in florida during 25 weeks in 1990-1, resulted in 222 laboratory-diagnosed cases, an attack rate in the 28 affected counties of 2.25/100,000. disease risk rose with advanced age, to 17.14/100,000 in persons over 80 years, and all 14 fatal cases were in persons over 55 years (median, 70 years). community serosurveys in indian river county, the epicenter of the outbreak (attack rate 21/100,000), showed acute asymptomatic infections in 3.6% of the persons sur ... | 2000 | 11057975 |
| [seroprevalence of infection by st. louis encephalitis virus in the province of formosa]. | the aim of this work was to determine the prevalence of antibodies against st. louis encephalitis virus (sle) in human sera provided by the laboratory of epidemiological surveillance from formosa district (province of formosa, argentina) in 1995 and 1997. the tests used for this study were hemagglutination inhibition (hi) and neutralization (nt). the screening performed by nt test showed prevalences of 21% (60/284) and 32% (50/157) of antibodies in samples obtained in 1995 and 1997 respectively. ... | 2000 | 11188954 |
| arbovirus surveillance in south carolina, 1996-98. | arboviruses isolated and identified from mosquitoes in south carolina (usa) are described, including new state records for eastern equine encephalitis virus (eee), st. louis encephalitis virus (sle), flanders virus, tensaw virus (ten), and a variant of jamestown canyon virus (jc). mosquitoes were collected at 52 locations in 30 of 46 south carolina counties beginning in june 1996, and ending in october 1998, and tested for arboviruses. of 1,329 mosquito pools tested by virus isolation (85,806 mo ... | 2001 | 11345423 |
| encephalitis virus persistence in california birds: preliminary studies with house finches. | field-collected house finches of mixed sex and age were infected experimentally with either western equine encephalomyelitis (wee) or st. louis encephalitis (sle) viruses during the summer or fall of 1998 and maintained over the winter under ambient conditions. to detect natural relapse during the spring, 32 birds were bled weekly from february through june 1999, and then necropsied 1 yr after infection to detect chronic infections using a reverse transcription polymerase chain reaction (rt-pcr) ... | 2001 | 11372964 |
| dengue and other emerging flaviviruses. | flaviviruses are among the most important emerging viruses known to man. most are arboviruses (arthropod-borne) being transmitted by mosquitoes or ticks. they derived from a common ancestor 10-20000 years ago and are evolving rapidly to fill new ecological niches. many are spreading to new geographical areas and causing increased numbers of infections. traditionally, three clinical syndromes are recognized: fever-arthralgia-rash, viral haemorrhagic fever, and neurological disease, though for som ... | 2001 | 11531316 |
| serologic evidence for west nile virus infection in birds in the new york city vicinity during an outbreak in 1999. | as part of an investigation of an encephalitis outbreak in new york city, we sampled 430 birds, representing 18 species in four orders, during september 13-23, 1999, in queens and surrounding counties. overall, 33% were positive for west nile (wn) virus-neutralizing antibodies, and 0.5% were positive for st. louis encephalitis virus-neutralizing antibodies. by county, queens had the most seropositive birds for wn virus (50%); species with the greatest seropositivity for wn virus (sample sizes we ... | 2001 | 11585522 |
| nucleic acid sequence-based amplification assays for rapid detection of west nile and st. louis encephalitis viruses. | the development and application of nucleic acid sequence-based amplification (nasba) assays for the detection of west nile (wn) and st. louis encephalitis (sle) viruses are reported. two unique detection formats were developed for the nasba assays: a postamplification detection step with a virus-specific internal capture probe and electrochemiluminescence (nasba-ecl assay) and a real-time assay with 6-carboxyfluorescein-labeled virus-specific molecular beacon probes (nasba-beacon assay). the sen ... | 2001 | 11724870 |
| detection of st. louis encephalitis and western equine encephalomyelitis rna in mosquitoes tested without maintenance of a cold chain. | western equine encephalomyelitis and st. louis encephalitis viral rna can be detected 20 days after death of infected culex tarsalis in the absence of a cold chain. viral rna was detected with the reverse transcription-polymerase chain reaction in mosquitoes infected either parenterally or perorally in the laboratory and then killed and held for up to 20 days at 27 degrees c. cell culture assay and in situ enzyme immunoassay did not detect infectious virus in the same mosquitoes. | 2001 | 11804455 |
| phylogenetic analysis of the envelope gene of st. louis encephalitis virus. | the complete nucleotide sequences of the envelope gene of 62 geographic isolates of st. louis encephalitis (sle) virus were determined. phylogenetic analyses of the sequences, conducted using both maximum parsimony and neighbor-joining methods, included four other members of the japanese encephalitis serogroup. the results indicated that the sle isolates formed a monophyletic group in which isolates generally clustered according to geographic origin. isolates from panama and south america predom ... | 2001 | 11811684 |
| immunization with heterologous flaviviruses protective against fatal west nile encephalitis. | prior immunization of hamsters with three heterologous flaviviruses (japanese encephalitis virus [jev] sa14-2-8 vaccine, wild-type st. louis encephalitis virus [slev], and yellow fever virus [yfv] 17d vaccine) reduces the severity of subsequent west nile virus (wnv) infection. groups of adult hamsters were immunized with each of the heterologous flaviviruses; approximately 30 days later, the animals were injected intraperitoneally with a virulent new york strain of wnv. subsequent levels of vire ... | 2002 | 11927020 |
| detection of encephalitis viruses in mosquitoes (diptera: culicidae) and avian tissues. | abstract diagnostic assays for the detection of st. louis encephalitis (sle) and western equine encephalomyelitis (wee) viruses in mosquito pools and avian tissues were compared for sensitivity, accuracy and specificity. the in situ enzyme immunoassay (eia), plaque assay on vero cells, passage in aedes albopictus skuse c6/36 and c7/10 cells, antigen capture enzyme immunoassay (ac-eia), and single and multiplex reverse transcription-polymerase chain reactions (rt-pcr) were evaluated using pools o ... | 2002 | 11931031 |
| simulated overwintering of encephalitis viruses in diapausing female culex tarsalis (diptera: culicidae). | female culex tarsalis coquillett in reproductive diapause were infected per os or by intrathoracic inoculation with western equine encephalomyelitis (wee) or st. louis encephalitis (sle) viruses during "fall," maintained over a simulated "winter," and then tested for virus infection and transmission in vitro and in vivo after "vernal" termination. exposure of f1 progeny of field-collected females to cool temperatures and short daylength produced females in reproductive diapause that were relucta ... | 2002 | 11931262 |
| in vitro antiviral and antibacterial activity of commercial intravenous immunoglobulin preparations--a potential role for adjuvant intravenous immunoglobulin therapy in infectious diseases. | the identification of specific antimicrobial activity of intravenous immunoglobulin (ivig) preparations against particular microbial pathogens can assist in determining their therapeutic potential for specific infectious diseases. we analysed five different commercial ivig preparations for the presence of antibodies directed against a large panel of viral, bacterial, fungal and parasitic pathogens. all ivig batches contained high activity against herpesviruses types 1, 2, 6 and 7, as well as aga ... | 2002 | 11982967 |
| simultaneous detection of three mosquito-borne encephalitis viruses (eastern equine, la crosse, and st. louis) with a single-tube multiplex reverse transcriptase polymerase chain reaction assay. | three mosquito-borne human encephalitis viruses (eastern equine encephalitis virus [eee], st. louis encephalitis virus [sle], and la crosse encephalitis virus [lac]) are sympatric in the southeastern united states. however, little is known concerning the temporal and spatial pattern of the distribution of these viruses in this area. as part of surveillance activities to detect the transmission of these 3 viruses in the tennessee valley area, we developed a single-tube multiplex reverse transcrip ... | 2002 | 11998926 |
| drought-induced amplification of saint louis encephalitis virus, florida. | we used a dynamic hydrology model to simulate water table depth (wtd) and quantify the relationship between saint louis encephalitis virus (slev) transmission and hydrologic conditions in indian river county, florida, from 1986 through 1991, a period with an slev epidemic. virus transmission followed periods of modeled drought (specifically low wtds 12 to 17 weeks before virus transmission, followed by a rising of the water table 1 to 2 weeks before virus transmission). further evidence from col ... | 2002 | 12023912 |
| two new rhabdoviruses (rhabdoviridae) isolated from birds during surveillance for arboviral encephalitis, northeastern united states. | two novel rhabdoviruses were isolated from birds during surveillance for arboviral encephalitis in the northeastern united states. the first, designated farmington virus, is a tentative new member of the vesiculovirus genus. the second, designated rhode island virus, is unclassified antigenically, but its ultrastructure and size are more similar to those of some of the plant rhabdoviruses. both viruses infect birds and mice, as well as monkey kidney cells in culture, but their importance for hum ... | 2002 | 12023919 |
| age-related seroprevalence study for st. louis encephalitis in a population from cordoba, argentina. | a serological screening was performed in 615 individuals aged 0-87 years, living in the city of cordoba, argentina to study the relationship between antibody prevalence for the sle virus and age. a 13.98% prevalence of neutralizing antibodies was obtained and its relation to age was significantly high (p = 0.045). the highest seroprevalence was noted on individuals over 60 years old (>20%), whereas no subject under 10 was seropositive for this virus. our results confirm that the agent is endemic ... | 2002 | 12048540 |
| the japanese encephalitis serological group of flaviviruses: a brief introduction to the group. | | 2002 | 12082984 |
| emergence of usutu virus, an african mosquito-borne flavivirus of the japanese encephalitis virus group, central europe. | during late summer 2001 in austria, a series of deaths in several species of birds occurred, similar to the beginning of the west nile virus (wnv) epidemic in the united states. we necropsied the dead birds and examined them by various methods; pathologic and immunohistologic investigations suggested a wnv infection. subsequently, the virus was isolated, identified, partially sequenced, and subjected to phylogenetic analysis. the isolates exhibited 97% identity to usutu virus (usuv), a mosquito- ... | 2002 | 12095429 |
| st. louis encephalitis virus induced pathology in cultured cells. | apoptosis is a highly regulated process of cellular self-destruction with diverse functions in multicellular organisms. it is known to be one of the mechanisms of viral pathogenesis. st. louis encephalitis virus (slev), an arthropod-borne flavivirus, causes encephalitis disease of varying severity mostly in north america and in some regions of south america. this virus induces cytopathic effects in vertebrate cell lines, however, the mechanism by which this occurs is yet to be elucidated. slev i ... | 2002 | 12111422 |
| isolation of st. louis encephalitis virus from bats (tadarida b. mexicana) in texas. | a strain of st. louis encephalitis virus has been isolated from mexican free-tailed bats (tadarida b. mexicana) collected at the time of an outbreak of encephalitis in texas in 1964. | 1966 | 12325353 |
| persistence and amplification of st. louis encephalitis virus in the coachella valley of california, 2000-2001. | the introduction of a st. louis encephalitis virus (sle) genotype new to southeastern california during 2000 was followed by focal enzootic amplification in the coachella valley that was detected by seroconversions of 29 sentinel chickens in five of nine flocks of 10 chickens each, isolations of virus from 30 of 538 pools of 50 culex tarsalis coquillett females, and collection of 30 positive sera from 2,205 wild birds. this sle strain over wintered successfully and then amplified during the summ ... | 2002 | 12349864 |
| temporal and geographic genetic variation in culex nigripalpus theobald (culicidae: diptera), a vector of st. louis encephalitis virus, from florida. | a field population of culex (culex) nigripalpus theobald from vero beach, fl sampled monthly over a period of 24 mo, a colony sample and 10 geographic samples were analyzed for genetic variation at 14 enzyme loci using polyacrylamide gel electrophoresis. the cx. nigripalpus colony sample showed significantly lower genetic variation than the field-collected samples, measured by mean number of alleles per locus (colony 1.4 +/- 0.1 versus field 2.1 +/- 0.22), percentage of polymorphic loci (colony ... | 2002 | 12495183 |
| vector competence of california mosquitoes for west nile virus. | to identify the mosquito species competent for west nile virus (wnv) transmission, we evaluated 10 california species that are known vectors of other arboviruses or major pests: culex tarsalis, cx. pipiens pipiens, cx. p. quinquefasciatus, cx. stigmatosoma, cx. erythrothorax, ochlerotatus dorsalis, oc. melanimon, oc. sierrensis, aedes vexans, and culiseta inornata. all 10 became infected and were able to transmit wnv at some level. ochlerotatus, culiseta, and aedes were low to moderately efficie ... | 2002 | 12498652 |
| the extent of homologous recombination in members of the genus flavivirus. | the family flaviviridae includes important human pathogens, such as dengue (den) virus, yellow fever (yf) virus and hepatitis c virus, many of which have emerged or re-emerged in recent years. until recently, flavivirus evolution was thought to proceed in a clonal manner, with diversity generated mainly through the accumulation of mutational changes. however, this assumption has now been shown to be invalid, with homologous recombination demonstrated in all three genera of the flaviviridae: sinc ... | 2003 | 12560576 |
| wicking assays for the rapid detection of west nile and st. louis encephalitis viral antigens in mosquitoes (diptera: culicidae). | the recent outbreaks of west nile (wn) encephalitis and st. louis encephalitis (sle) in the united states have highlighted the need for rapid and specific methods of detecting arboviral antigens in mosquitoes. we evaluated rapid, field-usable assays for detecting and differentiating wn and sle viruses in mosquito pools, based on a patent-pending, immunochromatographic technology (vectest) formatted on a dipstick. the device provides results in less than 20 min and can be used in laboratories wit ... | 2003 | 12597660 |
| st. louis encephalitis in argentina: the first case reported in the last seventeen years. | | 2003 | 12604006 |
| epitope-blocking enzyme-linked immunosorbent assays for the detection of serum antibodies to west nile virus in multiple avian species. | we report the development of epitope-blocking enzyme-linked immunosorbent assays (elisas) for the rapid detection of serum antibodies to west nile virus (wnv) in taxonomically diverse north american avian species. a panel of flavivirus-specific monoclonal antibodies (mabs) was tested in blocking assays with serum samples from wnv-infected chickens and crows. selected mabs were further tested against serum samples from birds that represented 16 species and 10 families. serum samples were collecte ... | 2003 | 12624027 |
| antibody and interleukin-12 treatment in murine models of encephalitogenic flavivirus (st. louis encephalitis, tick-borne encephalitis) and alphavirus (venezuelan equine encephalitis) infection. | early and sustained treatment with interleukin-12 (il-12) ameliorated disease in a mouse model of infection with the encephalitogenic flavivirus, st. louis encephalitis virus (slev, japanese encephalitis serogroup). however, this effect was not reproduced in murine infections with either the flavivirus tick-bore encephalitis virus (tbev) or the alphavirus venezuelan equine encephalitis virus (veev). il-12 exacerbated tbev disease when used in conjunction with monoclonal antibody (mab), suggestin ... | 2003 | 12639298 |
| detection of anti-west nile virus immunoglobulin m in chicken serum by an enzyme-linked immunosorbent assay. | the emergence of west nile (wn) virus in new york and the surrounding area in 1999 prompted an increase in surveillance measures throughout the united states, including the screening of sentinel chicken flocks for antibodies. an enzyme-linked immunosorbent assay (elisa) for the detection of chicken immunoglobulin m (igm) to wn virus was developed, standardized, and characterized as a rapid and sensitive means to detect wn viral antibodies in sentinel flocks. serum specimens from experimentally i ... | 2003 | 12734241 |
| case records of the massachusetts general hospital. weekly clinicopathological exercises. case 17-2003. a 38-year-old woman with fever, headache, and confusion. | | 2003 | 12773652 |
| [another case of west nile fever in the netherlands: a man with encephalitis following a trip to canada]. | shortly after his return to the netherlands from a trip to ontario, a part of canada where infection with west-nile virus has been reported, a 69-year-old man became increasingly confused and generally unwell, accompanied by fever. the clinical picture was compatible with viral encephalitis and this was supported by eeg findings and the results of the cerebrospinal-fluid examination. mri of the brain did not contribute to the diagnosis. the patient was treated with aciclovir because herpes simpl ... | 2003 | 12784533 |
| experimental transmission of st. louis encephalitis virus by ochlerotatus j. japonicus. | ochlerotatus japonicus japonicus a newly discovered nonindigenous mosquito species in north america, and a colonized strain of culex pipiens were compared for their vector competence for st. louis encephalitis virus (sle). infection rates in oc. j. japonicus were 0-33% after feeding on chickens with viremias between 10(4.1) and 10(4.7) plaque-forming units (pfu)/ml of blood. in comparison, infection rates were 12-94% for cx. pipiens that fed on the same chickens. when fed on chickens with viremi ... | 2003 | 12825669 |
| viral meningitis and encephalitis: traditional and emerging viral agents. | in the united states, the annual number of central nervous system (cns) infections that occur as a result of viral agents far exceeds that of infections caused by bacteria, yeast, molds, and protozoa combined. the recent incursion of west nile virus (wnv) into north america has led to a dramatic change in the incidence and epidemiology of summer-associated viral cns disease. as a result of increased testing for wnv, lesser known viral causes of cns infection have been identified. even the epidem ... | 2003 | 12881794 |
| serologic evidence of west nile virus infection in horses, coahuila state, mexico. | serum samples were obtained from 24 horses in the state of coahuila, mexico, in december 2002. antibodies to west nile virus were detected by epitope-blocking enzyme-linked immunosorbent assay and confirmed by plaque reduction neutralization test in 15 (62.5%) horses. we report the first west nile virus activity in northern mexico. | 2003 | 12890327 |
| serologic evidence of west nile virus infection in horses, yucatan state, mexico. | serum samples were obtained from 252 horses in the state of yucatan, mexico, from july to october 2002. antibodies to west nile virus were detected by epitope-blocking enzyme-linked immunosorbent assays in three (1.2%) horses and confirmed by plaque reduction neutralization test. we report the first west nile virus activity in the state of yucatan. | 2003 | 12890328 |
| previous infection protects house finches from re-infection with st. louis encephalitis virus. | antibody titers against st. louis encephalitis virus (sle) measured by a plaque reduction neutralization test (prnt) decreased rapidly in house finches (capodacus mexicanus) after initial infection, whereas antibodies measured by enzyme immunoassay (eia) remained detectable in all birds for the length of the experiment, indicating long-term persistence and greater assay sensitivity of the eia. after 52 wk, birds were challenged by subcutaneous inoculation with the same strain of sle virus. virus ... | 2003 | 12943108 |
| immunoassay targeting nonstructural protein 5 to differentiate west nile virus infection from dengue and st. louis encephalitis virus infections and from flavivirus vaccination. | west nile virus (wnv) is an emerging flavivirus that has caused frequent epidemics since 1996. besides natural transmission by mosquitoes, wnv can also be transmitted through blood transfusion and organ transplantation, thus heightening the urgency of development of a specific and rapid serologic assay of wnv infection. the current immunoassays lack specificity because they are based on detection of antibodies against wnv structural proteins and immune responses to structural proteins among flav ... | 2003 | 12958248 |
| interference between st. louis encephalitis virus and western equine encephalomyelitis virus along a neuronal pathway. | | 1952 | 12981275 |
| effect of pregnancy upon the immunity of mice vaccinated against st. louis encephalitis virus. | | 1952 | 13011696 |
| the hemagglutinin of st. louis encephalitis virus. i. recovery of stable hemagglutinin from the brains of infected mice. | | 1953 | 13035118 |
| the hemagglutinin of st. louis encephalitis virus. ii. physico-chemical properties and nature of its reaction with erythrocytes. | | 1953 | 13035119 |
| the hemagglutinin of st. louis encephalitis virus. iii. properties of normal inhibitors and specific antibody; use of hemagglutination-inhibition for diagnosis of infection. | | 1953 | 13035120 |
| polyradiculopathy in man produced by st. louis encephalitis virus (sle). | | 1953 | 13076770 |
| propagation of st. louis encephalitis virus in cells of the ehrlich ascitic tumor of mice. | | 1953 | 13120899 |
| multiplication of st. louis encephalitis virus in mice exposed to roentgen radiation. | | 1956 | 13279127 |
| the relationship of the epidemic keratoconjunctivitis virus of sanders to the st. louis encephalitis virus. | | 1957 | 13411133 |