Diagnosis of foot-and-mouth disease by RT-PCR: evaluation of primers for serotypic characterisation of viral RNA in clinical samples.

Multiple primers designed from the 1D and 2AB regions of the foot-and-mouth disease (FMD) viral genome were evaluated extensively for the detection of all seven serotypes of the virus by reverse transcription polymerase chain reaction (RT-PCR) at the OIE/FAO World Reference Laboratory for FMD (WRL), Pirbright. The primers had been characterised previously elsewhere on a relatively small number of cell culture grown isolates and epithelial suspensions and had been shown to identify and differentiate all seven serotypes of FMD virus. The extended study evaluated several RT-PCR protocols on epithelial suspensions and supernatant fluids, resulting from their passage in cell culture, derived from clinical samples of diverse molecular characteristics. Each of the serotype-specific primers in selected RT-PCR protocols demonstrated suitable specificity and detected cell culture passaged isolates with some success but were not adequate for the serotyping of suspensions prepared from clinical samples of epithelium. The results showed that the primers can be used in RT-PCR procedures in conjunction with the routine detection methods of virus isolation and ELISA for the diagnosis and serotyping of FMD virus.