Demonstrating persistence of foot-and-mouth disease virus in African buffalo (Syncerus caffer) using BaseScope™ in situ hybridisation

BaseScope™ in situ hybridisation (Advanced Cell Diagnostics, USA) was used to detect foot-and-mouth disease virus (FMDV), species Aphthovirus vesiculae, in formalin-fixed paraffin-embedded tissues from African buffalo (Syncerus caffer, n = 15) culled from the Kruger National Park - where the South African territories (SAT)-1, -2 and - 3 serotypes are endemic - as part of their population management program. Foot-and-mouth disease viral RNA was consistently detected in the palatine tonsils and lungs, demonstrating these as primary sites of viral persistence. Detection in the retropharyngeal lymph nodes and interdigital skin was less frequent, while oropharyngeal tissue showed rare positivity. Other sampled tissues - including the tip of the ear, eyelid, tongue, lip, and coronary band - proved suboptimal for identifying FMDV-positive buffalo or carriers. These findings highlight the value of BaseScope™ for detecting low viral loads of FMDV in persistently infected African buffalo, with a notable predilection for the palatine tonsils and lungs.