FMD subunit vaccine produced using a silkworm-baculovirus expression system: protective efficacy against two type Asia1 isolates in cattle.

Cattle vaccinated with a single dose of subunit vaccine containing the capsid and 3C proteinase coding regions of foot-and-mouth disease virus (FMDV) Asia I/HNK/CHA/05 strain were protected when challenged 28 days later with a homologous virus. Here, the 50% bovine protective dose (PD(50)) test was performed to assess the potency of the subunit vaccine. When challenged with two Chinese isolates, the subunit vaccine could achieve 6.5 PD(50) (challenged with Asia I/HNK/CHA/05 strain) and 5.2 PD(50) (challenged with Asia I/JSL/05 strain) per dose.