Search for epizootic-like Venezuelan encephalitis virus at enzootic habitats in Guatemala during 1969-1971.
Abstract: Seventy-four strains of Venezuelan encephalitis (VE) virus recovered from sentinel hamsters or mosquitoes at enzootic habitats in Guatemala in the two years following the 1969 epidemic-equine epizootic were examined for ability to produce small plaques in Vero African green monkey kidney cell cultures, like isolates obtained during the epizootic. (a) One strain recovered from a sentinel hamster in late October 1969 at an enzootic habitat near the epicenter of the hemagglutination-inhibition (HI) and equine-virulence properties like epizootic virus; this strain retained its small plaque characteristic after inoculation and recovery from bloods of three horses. (b) None of the other 73 strains produced uniformly small plaques, but 31 formed a few small plaques among large ones. Virions from small plaques of five strains were cloned twice in Vero cell cultures. Four clones produced uniformly small plaques after one more passage in Vero cells; three had hemagglutination-pH properties compatible with epizootic virus or intermediate between epizootic and enzootic virus, but HI tests with these three hemagglutinins or with antibody to the fourth cloned strain showed them to be like Central American enzootic virus. One of three cloned strains tested in horses produced encephalitis and death in one of four horses; another strain produced encephalitis with recovery in one of two horses. (c) Thus these small Vero plaque clones resembled Central American enzootic strains of VE virus in HI and equine-virulence tests, and the small Vero plaque characteristic was not a satisfactory marker for consistently isolating equine-virulent, epizootic VE virions. Nevertheless, this technic led to recognition of one epizootic strain isolated at an enzootic habitat in Guatemala at the end of 1969 outbreak. Whether this strain was there before the outbreak or subsequently penetrated the habitat is uncertain. During the next two years, this strain did not become dominant in that enzootic focus.
Publication Date: 1976-06-01 PubMed ID: 7138DOI: 10.1093/oxfordjournals.aje.a112262Google Scholar: Lookup
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- Journal Article
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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This research paper investigates the similarities and discrepancies in characteristics of various strains of Venezuelan encephalitis (VE) virus, found in Guatemala during 1969-1971, comparing these with enzootic and epizootic strains by using a variety of tests, like plaque formation and their virulence in equines.
Examination of VE Virus Strains
- The research primarily focused on 74 strains of VE virus recovered from sentinel hamsters or mosquitoes in enzootic regions in Guatemala. These were specifically examined for their ability to produce small plaques in Vero African green monkey kidney cell cultures, mimicking isolates obtained during the epizootic or equine outbreak.
- Out of the 74 strains, only one strain, which was recovered from a sentinel hamster in late October 1969 scored positive in this test. This strain also demonstrated properties related to hemagglutination-inhibition (HI) and equine-virulence that were similar to the epizootic virus.
- The unique small plaque characteristic of this strain persisted even after it was inoculated and recovered from horse blood samples.
Further Findings on VE Virus Strains
- None of the other 73 strains produced uniformly small plaques, although 31 did form a few small plaques in addition to some large ones.
- Virions from the small plaques of these 31 strains were cloned and propagated in Vero cell cultures.
- Four out of five, after being subject to the cloning process, produced uniformly small plaques even after an additional passage in Vero cells. However, HI tests showed them to be similar to the Central American enzootic virus.
- Only one strain was identified to be potentially epizootic, isolated at an enzootic habitat in the aftermath of the 1969 outbreak. The origins and history of this strain remain uncertain.
Conclusion of the Study
- The researchers concluded that the small plaque characteristic is not a reliable indicator for consistently isolating equine-virulent, epizootic VE virions, as these characteristics were also seen in enzootic strains.
- Overall, increased recognition and understanding of these strain-specific properties will contribute to improved disease control strategies.
Cite This Article
APA
Scherer WF, Anderson K, Pancake BA, Dickerman RW, Ordonez JV.
(1976).
Search for epizootic-like Venezuelan encephalitis virus at enzootic habitats in Guatemala during 1969-1971.
Am J Epidemiol, 103(6), 576-588.
https://doi.org/10.1093/oxfordjournals.aje.a112262 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Antibodies, Viral / analysis
- Clone Cells
- Cricetinae / microbiology
- Culicidae / microbiology
- Disease Reservoirs
- Encephalitis Virus, Venezuelan Equine / pathogenicity
- Encephalomyelitis, Equine / microbiology
- Encephalomyelitis, Venezuelan Equine / immunology
- Encephalomyelitis, Venezuelan Equine / microbiology
- Guatemala
- Hemagglutination, Viral
- Horse Diseases / microbiology
- Horses
- Serotyping
- Viral Plaque Assay
- Virulence
Citations
This article has been cited 6 times.- Medina G, Garzaro DJ, Barrios M, Auguste AJ, Weaver SC, Pujol FH. Genetic diversity of Venezuelan alphaviruses and circulation of a Venezuelan equine encephalitis virus subtype IAB strain during an interepizootic period. Am J Trop Med Hyg 2015 Jul;93(1):7-10.
- Brault AC, Powers AM, Medina G, Wang E, Kang W, Salas RA, De Siger J, Weaver SC. Potential sources of the 1995 Venezuelan equine encephalitis subtype IC epidemic. J Virol 2001 Jul;75(13):5823-32.
- Wiebe ME, Scherer WF. Virion envelope glycoproteins as epidermiological markers of Venezuelan encephalitis virus isolates. J Clin Microbiol 1980 Apr;11(4):349-54.
- Scherer WF, Chin J. Sensitivity of Toxorhynchites amboinensis mosquitoes versus chicken embryonic cell cultures for assays of Venezuelan encephalitis virus. J Clin Microbiol 1981 May;13(5):947-50.
- Jahrling PB, Heisey GB, Hesse RA. Evaluation of vascular clearance as a marker for virulence of alphaviruses: disassociation of rapid clearance with low virulence of venezuelan encephalitis virus strains in guinea pigs. Infect Immun 1977 Aug;17(2):356-60.
- Scherer WF, Pancake BA. Comparisons of Venezuelan encephalitis virus strains by hemagglutination-inhibition tests with chicken antibodies. J Clin Microbiol 1977 Dec;6(6):578-85.
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