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Cite this publication as: ICTVdB Management (2006). 00.073.0.01.008. Eastern equine encephalitis virus. In: ICTVdB - The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA
Cite this site as: ICTVdB - The Universal Virus Database, version 4. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
Host of Isolate and Habitat Details
Source of
isolate: horses.
Virus was isolated from adults.
Collection and Isolation Details
Virus was
isolated by Ten, Broeck and Merrill. The United States of America.
Reference to Isolation Report
Ten, Broeck & Merrill (1933). Proc. Soc. Exp. Biol. Med. 31
217-220.
ICTVdB Virus Code: 00.073.0.01.008. Virus accession number:
73001008. Obsolete virus code: 73.0.1.0.008; superceded accession number:
73010008.
NCBI Taxon Identifier NCBI Taxonomy ID:
11021.
ICTV approved acronym: (EEEV). Virus is an ICTV approved species. Virus is of the genus 00.073.0.01. Alphavirus; of the family 00.073. Togaviridae; not assigned to an order.
Distinct viral structures are visible in thin sections of infected tissue and nucleic acid of virions is encapsidated. Size and shape of virus has been determined by electron microscopy.
Virion populations are comprised of particles of uniform size. Capsids all have the same appearance and only one species is recovered in preparations.
Reference to nucleotide sequence in PubMed: reference(s). GenBank records for nucleotide sequences; complete genome sequences.
The viral genome encodes structural proteins and non-structural proteins. Virions consist of 5 structural protein(s) located in the envelope (E1, E2, E3), nucleocapsid (C) (6k). The viral envelope contains 3 integral membrane proteins.
Structural Proteins: Envelope protein E1. Envelope protein has been sequenced and a function assigned (E1 is 439 amino acids long and is postulated to serve as a fusion protein which possess(es) entry function into the cell. Envelope protein E2 has been sequenced and a function assigned (E2 is 423 amino acids long, is a transmembrane protein. During post-translational processing envelope protein modifications occur that include glycosylation. Envelope protein E3; has been sequenced and a function assigned (E3 is 60 amino acids long, is an attachment protein which possess(es) probably a signal function for E2. Nucleocapsid protein C; has a molecular mass of 30000 Da; is the product of the polyprotein encoded on the 3' end of the genome by the S-ORF, as are the other structural proteins; has been sequenced.
Non-Structural Proteins: Virus-coded non-structural proteins have been identified by sequence analysis and 4 non-structural protein(s) are found (nsP1, nsP2, nsP3, nsP4). The virus codes for enzymes, or replication-associated proteins; an RNA-dependent RNA polymerase. In addition to the polymerase, the virus codes for enzymes such as helicase, protease, replicase, and synthetase. The non-structural proteins are thought to be involved in capping of viral RNAs, initiation of negative strand RNA synthesis, processing of non-structural proteins, in RNA replication, the formation of a replicase complex for the minus strand synthesis, and the synthesis of the plus strand; function in the cytoplasm of infected cells; polymerase nsP4. Virus coded polymerase has a molecular mass of 19 kDa. Polymerase has been sequenced. The sequence has the accession number [P89949]. Non-structural protein polyprotein 1; has a molecular mass of 277 kDa has been sequenced and a function assigned. The protein is coded from NS-ORF; a replication-associated protein (capping of viral RNAs and initiating negative strand RNA synthesis) possesses methyltransferase activity. Non-structural protein nsP2 has been sequenced and a function assigned. The protein is coded from NS-ORF. The protein is a replication-associated protein (functions as a protease to process the nonstructural proteins, and as a helicase for RNA replication). Non-structural protein nsP3. Non-structural protein has been sequenced and a function assigned; the protein is coded from NS-ORF. Non-structural protein nsP4; has been sequenced, or a function assigned.
On the fly genome map for NC_003899.
The process of intracellular uncoating of virions is understood. Virus uncoating occurs in the cytoplasm; the viral nucleocapsid is delivered to the cell cytoplasm, the site of mRNA and subgenomic mRNA transcription.
By itself, genomic nucleic acid is infectious.
Infection and Replication: Virus replication is initiated by the insect host; occurs in the midgut or proceeds to salivary glands. In the vertebrate host virus replication occurs in various organs. Replication is not restricted to a particular tissue or organ of the host. Although severity of illness depends on route and dose, the majority of infections are subclinical, or mild. Infection involves a noncytocidal productive infectious cycle (in the invertebrate host), or does not involve a noncytocidal productive infectious cycle (in the mammalian host). Infected cells from arthropods continue to grow slowly and do not continue to grow (in case of vertebrates).
Transcription: The 5' ends of mRNAs are capped. The 3' ends of mRNAs possess a poly (A) tract.
Translation: The genome replicates in the cytoplasm.
Serological relationships between different members are very close (but relationships depends on antigenic complex membership). Cross-reactivity is found. Cross-reactivity between isolates of the same species and species, but not genera. Protective immunity is induced in the form of neutralizing antibodies. Virions are usually satisfactorily stabilized for use as antigens or immunogens by fixation with glutaraldehyde (or any of many other fixatives). The virus is immunogenic. The virus serves as an efficient immunogen when animals are infected with whole virus particle preparations, or disrupted virus particle preparations, or denatured virus particle preparations. These preparations produce antibodies. The virus induces antibodies with distinct reactivities to the subtype-specific determinants, or type-specific determinants, or serogroup-specific determinants, or complex-specific determinants, or genus-specific determinants. The virus induces the formation of neutralizing antibodies, or hemagglutination inhibiting antibodies, or complement-fixing antibodies. Antibody response that is protective against infection is usually directed against virion glycoproteins, or virion surface proteins. The serotype is defined by E proteins. The virus serotype is determined by a serum neutralization test; using polyclonal antibodies. Antigenic distances between individual species, expressed as serological indices, are correlated with the degree of sequence difference in their coat protein (E1 and E2). Species that are serologically interrelated have antigenic homologies with different isolates of the same virus species. Although the degree of antigenic specificity varies with the degree of relatedness, the antigenicity is considerable between isolates of the same virus species, or species of the same serogroup. Some species in the genus are related antigenically. They are sharing some epitopes in the structural proteins (40% homology), or in the non-structural proteins (60% homology). The virus is closely related to other viruses of the EEV complex and related to all other alphaviruses. Classification of members of this taxon is based on their sequence homologies. Minor biological differences have been recognized between EEE virus isolates. Known sequence homologies with other viruses. Sequence homologies phylogenetic analyses using nonstructural protein amino acid sequences indicate that alphaviruses evolved from a common ancestor which existed a few thousand years ago. Reliable virus detection and identification can be achieved by electron microscopy, or serological tests, or PCR techniques, or using specific primers.
Vaccines are restricted for use in humans.
Domain Eucarya
Kingdom Animalia.
Kingdom Animalia
Phylum Arthropoda and
Chordata.
Phylum Arthropoda
Subphylum Hexapoda; Class
Insecta; Subclass Pterygota (winged insects), Order Diptera.
Phylum Vertebrata
Subphylum Vertebrata.
Class Aves and Mammalia.
Class Aves Order Galliformes; virus infects
Family Phasianidae.
Virus infects Gallus and Phasianus.
Class Mammalia Order Perissodactyla and
Primates;
Family Hominidae.
Virus infects Homo sapiens
(human,
Family Equidae: virus infects Equus caballus
(horse).
General Symptoms in Animals Infection can affect the nervous system, musculo-skeletal system, and dermis, mucosa or epithelium. General symptoms include headache, or malaise, or photophobia, or prostration, or pyrexia, or retardation, or stiff neck, or tremor, or uncoordination. Lesions are found in nerve tissue. Signs and symptoms include meningitis, paralysis, sequelae, seizures, encephalitis.
Host 2: Birds (chicken, pheasant). The infection is clinically expressed. Infection is apparent (Birds vary in their susceptibility, with some birds developing disease). Signs and symptoms may vary, but are usually severe; persist (EEE virus persists in the feather follicles of infected pheasants). Prevalence of viral infection is seasonally dependent, and incidences are usually observed in summer. In naturally infected hosts morbidity rate may be as high as 50-70 % (case fatality rate in birds).
Host 3: Horses (Equus caballus). Infection is apparent. The infection is clinically expressed. Although disease expression is dependent on dose, infection is usually acute. Signs and symptoms may vary, but are usually severe. The North American strains of EEE are amongst the most virulent of the alphavirus). Prevalence of viral infection is seasonally dependent, and incidences are usually observed after heavy rainfalls (which are followed by an increased mosquito population). Contagiousness is variable; the incubation period lasts usually 5 day(s). In naturally infected hosts mortality rate may approach 90 % (case fatality rate in horses).
Host 4: Under natural conditions virus infects Humans (Homo sapiens). Infection is apparent. Human infections are unusual. A median of five cases are observed in the U.S.A. among approximately 23 inapparent infections. Children are more susceptible). The infection is clinically expressed. Although disease expression is dependent on dose, infection is usually acute. Signs and symptoms may vary, but are usually severe. Prevalence of viral infection is seasonally dependent, and incidences are usually observed in summer and after heavy rainfalls (which are followed by an increased mosquito population). In naturally infected hosts morbidity rate may be as high as 5 % and mortality rate may approach 30-60 % (; children are most severely affected).
Virus is transmitted by arthropods, by insects of the order Diptera, family Culicidae, Culicinae (culicine mosquitoes). Virus is transmitted in a persistent manner; retained when the vector moults; circulates in hemolymph; does not require a helper virus for vector transmission.
Non-Vector Transmission: The likelihood of viral transmission by respiratory route (air-borne) is low; faecal-oral route (water and food-borne) is low; direct contact is low; through sexual contact is low; through parenteral transmission is low; through blood or blood products is low; through congenital (germ line) transmission is rare; through transplacental transmission is rare; through perinatal transmission is rare.
Host:
Experimental host is susceptible to infection mice.
Experimentally infected hosts mainly show symptoms of similar neuro-virulence.
Host 2: Virus infects under experimental conditions guinea pigs, hamster, chickens, ducks.
Histopathology: Histopathologic lesions are found in brain. Virions are found in the cytoplasm. Primary histological changes include inflammation, or necrosis.
BR85-436087, PA86-435731, BR56-BeAn5122, MX97-1076, GA91-POREE, FL96-14834,
TX95-PV5-2547, FL93-939, TX91-VR1-7164, MS83-4789, LA50-arth167, CO92-49,
VE96-250714, BR83-416361, BR83-414556, BR78-348998, BR77-77U1, BR75-300851,
PE75-75U40, GU68-68U230, BR67-126650, BR65-81828, BR60-18205, 91031, 435731,
PE6 vaccine, Pan 66058-60, IVIC Pan 57151, El Delirio, 70U1104, TenBroeck, Tr24443,
GML903866, 75V-1496, GML900188, 76V-25343, GML 207963 , MARU 435731, Tr 25714,
ArgM, ArgB, ArgLL, 32-14-989, Ar5-9690, 89-42687, 91-32277, A61-1K, DV2 60-82, 74-33620,
69-7836, MP-9, 2061-88, 89-45989, NJ-1959, 89-47595, Hammon, R-35108, R53442, W-27933, JW, 7761, 08-3-0855, 664, B64-5282.01, BeAn-5122, 10365, Sanchez, WiAn 5000-03, Williams, 215-85, ME77132, NJ/60, 3076-90, Decuir, antigenic subtype of the North American variant (isolate 4789), South American strain, VA33.
Volchkov VE, Volchkova VA and Netesov SV (1991). Complete nucleotide sequence of the Eastern equine encephalomyelitis virus genome. Mol. Gen. Mikrobiol. Virusol. 5, 8-15
Franklin RP, Kinde H, Jay MT, Kramer LD, Green EN, Chiles RE, Ostlund E, Husted S, Smith J, Parker MD (2002). Eastern Equine Encephalomyelitis Virus Infection in a horse from California. Emerging Infectious Disease 8, 283-285.
The following generic references are cited in the most recent ICTV REport .
PubMed References. A description of this taxon can also be found on the web at U.S. Centers for Disease Control and Prevention (CDC), National Center for Infectious Diseases (NCID) (and the NJ Department of Health and Senior Services).
 | The description has been generated automatically from DELTA files. |
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ICTVdB - The Universal Virus Database, developed for the International Committee on Taxonomy of Viruses (ICTV) by Dr Cornelia Büchen-Osmond, is written in DELTA. The virus descriptions in ICTVdB are coded by ICTV members and experts, or by the ICTVdB Management using data provided by the experts, the literature or the latest ICTV Report. The character list is the underlying code. All virus descriptions are based on the character list and natural language translations from the encoded descriptions are automatically generated and formatted for display on the Web.
Developer of the DELTA software: M. J. Dallwitz, T. Paine and E. Zurcher
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Comments to ICTVdB Management
Last updated on
25 April 2006 by Cornelia Büchen-Osmond
Copyright © 2002 International Committee on Taxonomy of
Viruses. All rights reserved.
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