Consistent with the above described trans-encapsidation results, incubation of viruses that were obtained from the FMDV-SAT1 and FMDV-SAT2 co-infection with anti-SAT1 antiserum did not prevent transfer of the FMDV-SAT1 genome to the cells in the next round of infection, whereas incubation with both anti-SAT1 and anti-SAT2 antisera resulted in no detectable SAT1 RNA (Figure 3d). This evidence concerns the gene SAT2 and infection.