Serogrouping and topotyping of Sudanese and United States strains of epizootic hemorrhagic disease virus using PCR.

The potential use of the recently reported polymerase chain reaction (PCR) protocol for detection of United States epizootic hemorrhagic disease virus (EHDV) serotype 1 (EHDV-1) and serotype 2 (EHDV-2) ribonucleic acid in cell culture and clinical specimens was evaluated for detection of Sudanese EHDV strains. EHDV serotype 5 (EHDV-5) and EHDV, isolate 318 (untyped) designated (EHDV-318), recovered from sentinel calves at the Khartoum University farm (Sudan) were studied. RNA from EHDV-5 and EHDV-318 and a number of EHDV field isolates, propagated in cell cultures, were detected by the described PCR-based assay. The specific 387 bp PCR products were visualized on ethidium-bromide stained agarose gel. Specificity of the PCR products was confirmed by chemiluminescent hybridization with non-radiolabeled internal probe. Amplification product was not detected when the PCR-based assay was applied to RNA from blutongue virus (BTV) prototypes serotypes 2, 10, 11, 13, 16 and 17; total nucleic acid extracts from uninfected BHK-21 cells. The results of this study indicated that the previously described EHDV-PCR assay could be applied for detection of Sudanese as well as United States strains of EHDV serogroup. In addition, the described EHDV-PCR assay could be used as a supportive diagnostic assay to the current conventional virus isolation procedures used for detection of EHDV infection in susceptible ruminants.