Detection of foot-and-mouth disease virus with DNA probes in bovine esophageal-pharyngeal fluids.

Infectivity and dot-blot hybridization techniques were compared for the detection of FMDV in esophageal-pharyngeal fluids from experimentally infected cows. The probe used includes the viral polymerase sequence which allows the detection of the three types of virus (A, O, and C) with equivalent sensitivity. Virus was detected by dot-blot hybridization as well as by infectivity, according to sample analysis of esophageal-pharyngeal fluids extracted seven days post-infection. It was not possible to recover infective virus from some samples extracted at 180 and 560 days post-infection, although specific viral RNA was detected by dot-blot hybridization. This could indicate the presence of a high ratio of non-infective viral mutants in FMDV carrier cattle. These results emphasize the usefulness of molecular hybridization techniques for FMDV carrier-state detection.