Foot-and-mouth disease virus (FMDV) circulates as multiple serotypes and strains in
many endemic regions. In particular the three Southern African Territories (SAT) serotypes
are maintained effectively in their wildlife reservoir, the African buffalo, and individuals may
harbour multiple SAT-serotypes for extended periods in the pharyngeal region. However the
exact site and mechanism for persistence remain unclear. FMD in buffaloes offers a unique
opportunity to study FMDV-persistence, as transmission from carrier ruminants has only
convincingly been demonstrated for this species. Following co-infection of naïve African
buffaloes with three SAT-serotypes isolated from field buffaloes; palatine tonsil swabs were
the sample of choice for recovering infectious FMDV up to 400 days post infection (dpi).
Post-mortem examination identified infectious virus for up to 185 dpi and viral genome up to
400 dpi in lymphoid tissue of the head and neck, mainly focussed in germinal centres.
Interestingly viral persistence in vivo was not homogenous and the SAT-1 isolate persisted
for longer than SAT-2 and SAT-3. Co-infection and passage of these SAT isolates in goat
and buffalo cell lines demonstrated a direct correlation between persistence and cell killing
capacity. These data suggest FMDV persistence occurs in the germinal centres of lymphoid
tissue but the duration of persistence is related to virus replication and cell killing capacity.