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Journal of Clinical Microbiology, April 2000, p. 1527-1535, Vol. 38, No. 4
Institute for Medical Microbiology,
Infectious and Epidemic Diseases, Ludwig-Maximilians University,
Munich, Germany,1 and Division of
Vector-Borne Infectious Diseases, National Center for Infectious
Diseases, Centers for Disease Control and Prevention, Public Health
Service, U.S. Department of Health and Services, Fort Collins,
Colorado,2 and Naval Medical
Research Center Detachment, NAMRID, Unit 3800 APO AA 34031, Peru3
Received 13 September 1999/Returned for modification 16 November
1999/Accepted 3 December 1999
Specific and sensitive reverse transcription-PCR (RT-PCR) assays
were developed for the detection of eastern, western, and Venezuelan
equine encephalitis viruses (EEE, WEE, and VEE, respectively). Tests
for specificity included all known alphavirus species. The EEE-specific
RT-PCR amplified a 464-bp region of the E2 gene exclusively from 10 different EEE strains from South and North America with a sensitivity
of about 3,000 RNA molecules. In a subsequent nested PCR, the
specificity was confirmed by the amplification of a 262-bp fragment,
increasing the sensitivity of this assay to approximately 30 RNA
molecules. The RT-PCR for WEE amplified a fragment of 354 bp from as
few as 2,000 RNA molecules. Babanki virus, as well as Mucambo and
Pixuna viruses (VEE subtypes IIIA and IV), were also amplified.
However, the latter viruses showed slightly smaller fragments of about
290 and 310 bp, respectively. A subsequent seminested PCR amplified a
195-bp fragment only from the 10 tested strains of WEE from North and
South America, rendering this assay virus specific and increasing its
sensitivity to approximately 20 RNA molecules. Because the 12 VEE
subtypes showed too much divergence in their 26S RNA nucleotide
sequences to detect all of them by the use of nondegenerate primers,
this assay was confined to the medically important and closely related
VEE subtypes IAB, IC, ID, IE, and II. The RT-PCR-seminested PCR
combination specifically amplified 342- and 194-bp fragments of the
region covering the 6K gene in VEE. The sensitivity was 20 RNA
molecules for subtype IAB virus and 70 RNA molecules for subtype IE
virus. In addition to the subtypes mentioned above, three of the
enzootic VEE (subtypes IIIB, IIIC, and IV) showed the specific amplicon
in the seminested PCR. The practicability of the latter assay was
tested with human sera gathered as part of the febrile illness
surveillance in the Amazon River Basin of Peru near the city of
Iquitos. All of the nine tested VEE-positive sera showed the expected
194-bp amplicon of the VEE-specific RT-PCR-seminested PCR.
0095-1137/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Development of Reverse Transcription-PCR Assays
Specific for Detection of Equine Encephalitis Viruses
*
Corresponding author. Mailing address: Institute for
Medical Microbiology, Infectious and Epidemic Diseases,
Veterinaerstr. 13, D-80539 Munich, Germany. Phone: 49-89-2180-2593. Fax: 49-89-2180-2597. E-mail:
Martin.Pfeffer{at}micro.vetmed.uni-muenchen.de.
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