GENETIC TARGETS FOR THE DETECTION AND IDENTIFICATION OF VENEZUELAN EQUINE ENCEPHALITIS VIRUSES

Rt-PCR probes targeted to different gene sequences of VEE (Venezuelan equine encephalitis) virus strain TC-83 were assessed for their sensit ivity, specificity and non-specific cross-reactivity. A generic VEE vi rus amplimer (VNSP4F2/VNSP4R2), targeted against nsP4 was identified, which was sensitive (detected at least 10 pfu) and robust (worked over a wide range of salt concentrations and annealing temperatures). An E 2 amplimer designed against TC-83, (VE2F/VE2R), identified VEE strains TRD (1AB), P676 (1C), 3880 (1D) Everglades (2) vRNA whilst a second E 2 primer pair designed against strain 68U201, (68UF/68UR), identified all the remaining VEE viruses in the sere-complex. This would suggest that the VEE virus E2 gene can be sub-divided at the genetic level int o two separate groups making it a useful target for differentiation of sero-subtypes 1 and 2 from the other VEE virus subtype. Using a panel of amplimers targeted to different VEE genes and strains it was possi ble to distinguish between most of the serotypes, but most importantly , we were able to detect the epizootic strains TRD and P676 as well as other VEE viruses implicated in human disease (sero-subtypes 1D and 1 E).