Primary diagnosis of foot-and-mouth disease by reverse transcription polymerase chain reaction.

Universal and serotype-specific primer sets were used in simple reverse transcription polymerase chain reaction (RT-PCR) assays on field samples of epithelium and vesicular fluid to determine their suitability for primary diagnosis of all seven serotypes of foot-and-mouth disease (FMD). The specificity of reactions was confirmed by using other vesicular disease viruses, namely: swine vesicular disease virus, vesicular stomatitis virus and three vesiviruses. This resulted in the identification of a universal O/A/C/Asia 1 primer set (1F/1R) located in the 5' untranslated region (UTR) of the FMD virus genome for the successful detection of virus of these serotypes in clinical samples although this primer set detected FMD virus of the SAT1/2/3 serotypes less efficiently. The 5' UTR universal primer set could be used for the primary diagnosis of FMD in conjunction with the routine diagnostic methods of virus isolation in cell culture and ELISA, although a more favourable reaction would be expected with FMD viruses of the O/A/C/Asia 1 group than with those of the SAT serotypes. The other examined universal and serotype-specific primer sets, located principally in the P1 capsid-coding region, were generally inferior to the 5' UTR universal primer set. It is envisaged that this evaluation of primers will lead to the development of alternative PCR strategies, for example nested PCR formats, with concomitant improvement in the speed of primary diagnosis of FMD which under present procedures can be lengthy.