Laboratory studies of Venezuelan equine encephalitis virus in equines, Texas, 1971.
Abstract: During the summer and fall of 1971, epizootic and epidemic Venezuelan equine encephalitis was detected in Texas. Isolates of epizootic (IB) and vaccine (TC-83) strains were distinguished by virulence of the former for guinea pigs. Vaccine virus was isolated from 1 to 14 days after vaccination and neutralization tests demonstrated the appearance of antibody about a week after vaccination. Viremia titers of subtype IB in horses ranged from 2.2 to 8.3 log10 suckling mouse intracranial 50% lethal doses per ml. Of 101 equines from which Venezuelan equine encephalitis virus (IB or TC-83) strains were isolated, 87 had no neutralizing antibody against Venezuelan, eastern or western equine encephalitis viruses.
Publication Date: 1975-09-01 PubMed ID: 1176627PubMed Central: PMC274171DOI: 10.1128/jcm.2.3.198-205.1975Google Scholar: Lookup
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Summary
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This research article explores studies on the Venezuelan equine encephalitis virus (VEEV) in horses in Texas during 1971. The study revealed that both epizootic (IB) and vaccine (TC-83) strains of VEEV were present and the former showed a high virulence in guinea pigs. The virus was isolated up to 14 days after vaccination and the appearance of antibodies could be detected roughly a week following vaccination.
Virus Strains
- The study identified the presence of both epizootic (IB) and vaccine (TC-83) strains of the Venezuelan equine encephalitis virus (VEEV) in horses.
- The IB strain proved to be highly virulent when tested in guinea pigs. The virulence of a virus refers to its ability to infect and cause disease in a host organism.
Vaccine Efficacy
- Virus of the vaccination strain (TC-83) was still capable of being isolated from the horses anywhere from 1 to 14 days after they had been vaccinated.
- This suggests that the vaccination does not immediately clear the virus from the system. However, it initiates an immune response leading to the production of antibodies against the VEEV. The presence of these antibodies could be confirmed about a week after vaccination.
Viremia and Antibody Production
- Viremia, the presence of viruses in the blood, resulted in titers of subtype IB ranging between 2.2 to 8.3 log10 suckling mouse intracranial 50% lethal doses per ml. This shows the potency and capacity of the virus to cause disease.
- Out of 101 horses from which the virus was isolated, 87 did not have any neutralizing antibodies against VEEV or related eastern or western equine encephalitis viruses.
- Neutralizing antibodies are critical in viral infection control as they prevent viruses from being able to infect cells. Their absence could lead to increased susceptibility to the diseases.
Cite This Article
APA
Calisher CH, Maness KS.
(1975).
Laboratory studies of Venezuelan equine encephalitis virus in equines, Texas, 1971.
J Clin Microbiol, 2(3), 198-205.
https://doi.org/10.1128/jcm.2.3.198-205.1975 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Antigens, Viral / analysis
- Disease Outbreaks / veterinary
- Encephalitis Virus, Venezuelan Equine / immunology
- Encephalitis Virus, Venezuelan Equine / isolation & purification
- Encephalitis Virus, Venezuelan Equine / pathogenicity
- Encephalomyelitis, Equine / veterinary
- Encephalomyelitis, Venezuelan Equine / microbiology
- Encephalomyelitis, Venezuelan Equine / veterinary
- Guinea Pigs
- Horse Diseases / microbiology
- Horses
- Mice
- Texas
- Vaccination
- Viral Vaccines
- Virulence
References
This article includes 10 references
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- Henderson BE, Chappell WA, Johnston JG Jr, Sudia WD. Experimental infection of horses with three strains of Venezuelan equine encephalomyelitis virus. I. Clinical and virological studies.. Am J Epidemiol 1971 Mar;93(3):194-205.
- Calisher CH, Maness KC. Virulence of Venezuelan equine encephalomyelitis virus subtypes for various laboratory hosts.. Appl Microbiol 1974 Nov;28(5):881-4.
- Pedersen CE Jr, Robinson DM, Cole FE Jr. Isolation of the vaccine strain of Venezuelan equine encephalomyelitis virus from mosquitoes in Louisiana.. Am J Epidemiol 1972 May;95(5):490-6.
- Young NA, Johnson KM. Antigenic variants of Venezuelan equine encephalitis virus: their geographic distribution and epidemiologic significance.. Am J Epidemiol 1969 Mar;89(3):286-307.
- Sudia WD, Newhouse VF. Epidemic Venezuelan equine encephalitis in North America: a summary of virus-vector-host relationships.. Am J Epidemiol 1975 Jan;101(1):1-13.
- Mack TM, Thomas DB, Ali A, Muzaffar Khan M. Epidemiology of smallpox in West Pakistan. I. Acquired immunity and the distribution of disease.. Am J Epidemiol 1972 Feb;95(2):157-68.
- Correa-Giron P, Calisher CH, Baer GM. Epidemic strain of Venezuelan equine encephalomyelitis virus from a vampire bat captured in Oaxaca, Mexico, 1970.. Science 1972 Feb 4;175(4021):546-7.
- Sudia WD, McLean RG, Newhouse VF, Johnston JG, Miller DL, Trevino H, Bowen GS, Sather G. Epidemic Venezuelan equine encephalitis in North America in 1971: vertebrate field studies.. Am J Epidemiol 1975 Jan;101(1):36-50.
- Sudia WD, Newhouse VF, Beadle ID, Miller DL, Johnston JG Jr, Young R, Calisher CH, Maness K. Epidemic Venezuelan equine encephalitis in North America in 1971: vector studies.. Am J Epidemiol 1975 Jan;101(1):17-35.
Citations
This article has been cited 1 times.- Bowen GS, Calisher CH. Virological and serological studies of Venezuelan equine encephalomyelitis in humans. J Clin Microbiol 1976 Jul;4(1):22-7.
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