DETECTION OF FOOT-AND-MOUTH-DISEASE VIRAL SEQUENCES IN VARIOUS FLUIDSAND TISSUES DURING PERSISTENCE OF THE VIRUS IN CATTLE

Objective-To assess whether foot-and-mouth disease virus (FMDV)-specif ic sequences could be identified in tissues from persistently virus-in fected animals. Design-Cattle with experimentally induced persistent F MDV infections were slaughtered at 750 days after viral exposure. Expe rimentally infected pigs were slaughtered at 28 days after FMDV inocul ation. Postmortem specimens were asceptically removed. Animals-Three b ovids and 3 pigs were studied, as well as 1 control animal for each sp ecies. Procedure-Various tissues were examined for the presence of FMD V-specific sequences by dot-blot hybridization assay, using a molecula rly cloned FMDV cDNA corresponding to the polymerase coding region. Re sults-The FMDV specific genomic sequences were only detected in RNA fr om spleen, lung, larynx, tonsils, pancreas, liver, esophagus, and WBC of bovids. Conclusions-It was established that, at late stages of the persistent infection, when virus isolation was not possible, cattle ma y carry FMDV-specific sequences in different tissues. Retention of vir al sequences could not be demonstrated in specimens from experimentall y infected swine, 28 days after viral inoculation.