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Query: UMLS:C0014070 (encephalomyelitis)
 13,017 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In an extension of recent work on the antigenic interrelationships of arthropod-borne viruses, the plaque-inhibition test has been applied to the study of 15 Group A strains. Middelburg and eastern equine encephalomyelitis viruses show no relationship to any other virus in the group. Sindbis and western equine encephalomyelitis viruses show a one-way relationship only. The remaining viruses all share some antigenic components which react with hyperimmune rabbit sera prepared against Semliki Forest virus. However, using single-dose rabbit sera, or more specific mouse-immune sera, four distinct subgroups can be defined. One includes Semliki Forest virus strains; another Chikungunya virus and its substrains, Vereeniging and TH 35 viruses; the third contains O'nyong-nyong virus; and the fourth Mayaro and Uruma viruses.This paper also demonstrates how the plaque-inhibition technique may be used for the rapid identification of new virus isolates.
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PMID:Cross-neutralization studies with group A arthropod-borne viruses. 1373 88

A prolongation in the lives of Swiss mice inoculated intracerebrally with lymphocytic choriomeningitis virus (LCM) was observed after treatment with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). A variety of treatment schedules, including therapy once or twice daily up to 17 days and single treatments at various times after virus inoculation, were employed. Virus titers ranging to greater than 10(4) were detected in the blood and brains of surviving drug-treated animals. In three comparative studies in which different treatment schedules were used, BCNU was shown to exert a protective effect approximately equal to that of methotrexate in LCM virus-infected mice. Tests were also carried out to investigate the activity of BCNU in mice experimentally infected with eastern equine encephalomyelitis (EEE) virus, western equine encephalomyelitis virus, Semliki Forest (SF) virus, herpes simplex virus, influenza virus strain PR8, vaccinia virus strain WR, Rous sarcoma virus, Friend leukemia virus (FLV), and poliovirus. Slight increases in life span were observed in the treated EEE, SF, and influenza PR8 virus-infected animals. Significant reduction in splenomegaly in FLV-infected animals treated with BCNU was demonstrated. The possible mechanisms of LCM virus inhibition by BCNU, on the basis of these and other studies, were postulated to be either specific antiviral activity or inhibition of "lethal" immune response to the LCM virus. Each of these postulates is discussed.
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PMID:IN VIVO ANTIVIRAL ACTIVITY OF 1,3-BIS(2-CHLOROETHYL)-1-NITROSOUREA. 1433 66

Three arthropod-borne alphaviruses, western equine encephalitis viruses (WEEV), eastern equine encephalitis viruses (EEEV) and Venezuelan equine encephalitis viruses are the aetiological agents of a sometimes severe encephalomyelitis in equines and humans in the New World. With regard to the different ecology and epidemiology of these viruses, a method applied in serological screening should be able to distinguish between them as well as other related members of the genus Alphavirus in the American continent. However, this has been hampered in the past by (a) the close antigenic relationship between alphaviruses in traditional serological assays, especially in the routinely used haemagglutination-inhibition, and (b) the need of biosafety level 3 facilities to grow the viral antigens. An epitope blocking assay using an EEEV glycoprotein E1-expressing recombinant Sindbis virus and virus-specific monoclonal antibodies (mAbs) binding to the E1 of EEEV (strain NJ/60) and the E1 of Sindbis virus was established using automated flow cytometry. The test was evaluated using sera of infected and vaccinated rabbits. A cut-off value of 30% inhibition for antigenic complex-specific seroconversion was found to be sufficient for the detection of the respective infection. By using three different mAbs in parallel, we were able to detect alphavirus genus-, EEEV- and WEEV-complex-specific serum antibodies. As this test is based on the inhibition of binding of virus-specific mAbs, sera of every origin other than mouse can be tested. Thus, this assay may prove useful in the serological screening of a variety of animal species during an outbreak investigation.
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PMID:Detection of antibodies to alphaviruses and discrimination between antibodies to eastern and western equine encephalitis viruses in rabbit sera using a recombinant antigen and virus-specific monoclonal antibodies. 1462 96

As part of a comprehensive study on the ecology of arthropod-borne viruses in the Amazon Basin region of Peru, we assayed 539,694 mosquitoes captured in Loreto Department, Peru, for arboviruses. Mosquitoes were captured either by dry ice-baited miniature light traps or with aspirators while mosquitoes were landing on human collectors, identified to species, and later tested on Vero cells for virus. In total, 164 virus isolations were made and included members of the Alphavirus (eastern equine encephalomyelitis, Trocara, Una, Venezuelan equine encephalomyelitis, and western equine encephalomyelitis viruses), Flavivirus (Ilheus and St. Louis encephalitis), and Orthobunyavirus (Caraparu, Itaqui, Mirim, Murutucu, and Wyeomyia viruses) genera. In addition, several viruses distinct from the above-mentioned genera were identified to the serogroup level. Eastern equine encephalomyelitis virus was associated primarily with Culex pedroi Sirivanakarn & Belkin, whereas Venezuelan equine encephalomyelitis virus was associated primarily with Culex gnomatos Sallum, Huchings & Ferreira. Most isolations of Ilheus virus were made from Psorophora ferox (Von Humboldt). Although species of the Culex subgenus Melanoconion accounted for only 45% of the mosquitoes collected, 85% of the virus isolations were made from this subgenus. Knowledge of the viruses that are being transmitted in the Amazon Basin region of Peru will enable the development of more effective diagnostic assays, more efficient and rapid diagnoses of clinical illnesses caused by these pathogens, risk analysis for military/civilian operations, and development of potential disease control measures.
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PMID:Isolation of viruses from mosquitoes (Diptera: Culicidae) collected in the Amazon Basin region of Peru. 1636 1

Active Eastern or Western equine encephalomyelitis virus in three forms,-chemically untreated but simply passaged through series of mice; adsorbed on alumina Gel C, and precipitated by tannin,-yielded practically the same results when employed for the immunization of guinea pigs. The virus is not inactivated by the process of adsorption or precipitation : guinea pigs and mice inoculated in the brain with these materials develop lethal encephalomyelitis in the same manner as when chemically untreated mouse passage virus has been used. Moreover, there is no difference in the rate of absorption in vivoof the chemically treated and untreated virus preparations. After storage of the three immunizing preparations-the longest periods thus far studied being 2 to 3 months for mouse passage and for precipitated suspensions, and 6 months for adsorbed material-each was found to contain an amount of virus sufficient to produce immunity in animals against the usual intracerebral test inoculation. Finally, the protection afforded by the three preparations is apparently durable, as is true of many active viruses utilized in preventive treatments. The amount of the virus necessary to confer protection may be defined as that which immunizes (a) with the least number of antigenic units and (b) with the minimum of febrile reaction and blood infection. In proportion as this amount is exceeded, the incidence of fever and of circulating virus increases and, on the other hand, as this amount is decreased, the degree of induced immunity is diminished. We have thus shown that for this particular virus and in the guinea pig, one or two subcutaneous doses of I cc. of any of the different virus preparations, each containing 3 x 10(3) to 3 x 10(4) mouse infective units, bring about protection regularly against experimental infection by way of the nose or subcutis. The results are irregular when the test is made by way of the brain. By three injections, resistance is invariably obtained against as many as 10(3) to 10(4) lethal doses, given intracerebrally. No matter in what form the virus is given, as mouse passage, or adsorbed, or precipitated material, in certain instances fever occurs and virus circulates. With the amount of virus adequate for immunization (3,000 to 30,000 m.i.u.) a mild or subclinical infection may occur in the guinea pig without other manifestation of disease. Lesser quantities of virus apparently fail to gain a foothold in the animal and thus fail to bring about resistance. To conclude, a quantitative basis has been established for the comparison of the immunizing capacities of preparations employed in experimental equine encephalomyelitis in guinea pigs.
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PMID:ACTIVE IMMUNICATION OF GUINEA PIGS WITH THE VIRUS OF EQUINE ENCEPHALOMYELITIS : I. QUANTITATIVE EXPERIMENTS WITH VARIOUS PREPARATIONS OF ACTIVE VIRUS. 1987 Apr 74

A specific complement fixation test can be obtained in various central nervous system virus infections by using as antigens emulsions of infected brain tissue, freezing and thawing the brain emulsion, and then centrifuging it in an angle head centrifuge at 3500 R.P.M. for 1 hour. The method has proved reliable in the case of rabies, St. Louis encephalitis, Japanese B encephalitis, lymphocytic choriomeningitis, Eastern equine encephalomyelitis, Western equine encephalomyelitis, louping ill, and spontaneous encephalomyelitis of mice (Theiler's disease). The specificity of the reaction, regardless of the virus involved, requires different temperatures of inactivation of the sera according to animal species: 56 degrees C. for guinea pig, 60 degrees C. for mouse, and 65 degrees C. for rabbit and dog sera, all heated for 20 minutes. For human sera a temperature of inactivation of 60 degrees C. also for 20 minutes has been adopted; at this temperature the reaction is in general specific. Complement-fixing antibodies in high titre were found in the sera of rabbits, guinea pigs, mice, and dogs immunized with rabies virus. Complement-fixing antibodies were present in high titre in sera drawn from two persons 8 years after an attack of louping ill, from five persons 2(1/2) years after an attack of Eastern equine encephalomyelitis, and from two persons 2(1/2) years after Western equine encephalomyelitis. In cases of St. Louis encephalitis and lymphocytic choriomeningitis, complement-fixing antibodies have been found shortly following infection but not after long periods.
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PMID:THE COMPLEMENT FIXATION TEST IN THE DIAGNOSIS OF VIRUS INFECTIONS OF THE CENTRAL NERVOUS SYSTEM. 1987 Nov 44

Under none of the experimental conditions here described was treatment of the infection induced by the virus of Western equine encephalomyelitis in mice and guinea pigs with specific hyperimmune rabbit serum effective if begun after the onset of signs of encephalitis. In mice, after intracerebral inoculation of virus, serum was ineffective when given even before that stage. After peripheral introduction of virus in guinea pigs the disease was completely arrested in certain animals by single or multiple doses of antiserum if treatment was begun within 24 to 48 hours after virus inoculation. In others the incubation period was prolonged to 2 or even as long as 7 weeks. In untreated guinea pigs, injection of virus alone led to active immunity in those which survived. Antiserum blocked the antigenicity of active virus in the serum-treated animals. The decrease in titer in the sera of all antiserum-treated animals proceeded at the same rate as in those of control guinea pigs which received antiserum alone. Thus it was not possible to predict which ones would survive and which would succumb after a prolonged incubation period. Delayed fatal disease occurred at a time when the neutralizing antibody of the treated guinea pigs had fallen to a low titer. It is therefore likely that the virus which persisted throughout this long incubation period had been prevented from passing to and infecting other cells but reached them when antibody fell to an ineffective level in the surrounding medium. The relative frequency of such delayed reactions limits to a further extent the degree to which antiserum can be depended on for effective treatment of infection with the virus of equine encephalomyelitis.
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PMID:INDUCED RESISTANCE OF THE CENTRAL NERVOUS SYSTEM TO EXPERIMENTAL INFECTION WITH EQUINE ENCEPHALOMYELITIS VIRUS : II. SEROTHERAPY IN WESTERN VIRUS INFECTION. 1987 Dec 90

Live animal trade is considered a major mode of introduction of viruses from enzootic foci into disease-free areas. Due to societal and behavioural changes, some wild animal species may nowadays be considered as pet species. The species diversity of animals involved in international trade is thus increasing. This could benefit pathogens that have a broad host range such as arboviruses. The objective of this study was to analyze the risk posed by live animal imports for the introduction, in the European Union (EU), of four arboviruses that affect human and horses: Eastern and Western equine encephalomyelitis, Venezuelan equine encephalitis and Japanese encephalitis. Importation data for a five-years period (2005-2009, extracted from the EU TRACES database), environmental data (used as a proxy for the presence of vectors) and horses and human population density data (impacting the occurrence of clinical cases) were combined to derive spatially explicit risk indicators for virus introduction and for the potential consequences of such introductions. Results showed the existence of hotspots where the introduction risk was the highest in Belgium, in the Netherlands and in the north of Italy. This risk was higher for Eastern equine encephalomyelitis (EEE) than for the three other diseases. It was mainly attributed to exotic pet species such as rodents, reptiles or cage birds, imported in small-sized containments from a wide variety of geographic origins. The increasing species and origin diversity of these animals may have in the future a strong impact on the risk of introduction of arboviruses in the EU.
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PMID:Identification of hotspots in the European union for the introduction of four zoonotic arboviroses by live animal trade. 2389 73

Summary Alphaviral equine encephalomyelitis is a mosquito-borne infection that causes severe neurological disease and fatalities in horses and humans in the Americas. Consequently, the equine alphaviruses (Eastern, Western and Venezuelan) are of considerable concern worldwide and are notifiable to the World Organisation for Animal Health. In addition, these diseases are considered a potent potential biological weapon, emphasising the need to develop an effective vaccine. Alphaviral equine encephalomyelitis is caused by Eastern equine encephalomyelitis virus (EEEV), Western equine encephalomyelitis virus (WEEV) or Venezuelan equine encephalomyelitis virus (VEEV), which are related members of the Alphavirus genus in the Togaviridae family. Although related, the three viruses are genetically and antigenically distinct. The disease is characterised by fever, anorexia, depression and clinical signs of encephalomyelitis, and may be fatal in up to 90% of cases, for both humans and horses, particularly in the case of EEE. Surviving horses develop lifelong immunity but may have permanent neuropathology. The aim of this paper is to analyse the scientific information available on the evolution of EEE, WEE and VEE, and any potential vaccines.
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PMID:Alphaviral equine encephalomyelitis (Eastern, Western and Venezuelan). 2660 51

Epidemiologic analysis of epidemic outbreaks caused by American equine encephalitis causative agents is carried out in the review. Eastern equine encephalomyelitis (EEE), Western equine encephalomyelitis (WEE) and Venezuela equine encephalomyelitis (VEE) viruses are etiologic agents of dangerous transmissive diseases that are usually accompanied by fever and neurologic symptoms. Among the New World alphaviruses, VEE virus has the most potential danger for humans and domestic animals. Currently, enzootic strains of VEE play an increasing role as etiologic agents of human diseases. Most of the VEE cases in humans in endemic regions during inter-epidemic period are caused by infection with VEE subtype ID virus. A possibility of emergence of novel epidemic outbreaks of VEE is determined by mutations of ID subtype strains into IC subtype, and those currently pose a potential threat as an etiologic agent of the disease. Despite low morbidity, EEE and WEE are a problem for healthcare due to a relatively high frequency of lethal outcomes of the disease.
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PMID:[EPIDEMIOLOGIC ANALYSIS OF OUTBREAKS OF DISEASES CAUSED BY AMERICAN EQUINE ENCEPHALITIS CAUSATIVE AGENTS IN ENDEMIC REGIONS]. 2682 61


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