Fig. 3
From: Towards improvements in foot-and-mouth disease vaccine performance
Alternative strategies to produce novel, safe, FMDV vaccines. a The production of 70S empty capsid particles by the co-expression of the FMDV P1-2A capsid precursor plus the 3Cpro has been achieved using baculovirus and vaccinia virus expression systems. The purified non-infectious particles can be used as a vaccine. b Defective viral vectors (e.g. human adenovirus Ad5 or Semliki Forest virus vectors) have been used to express the P1-2A plus 3Cpro within mammalian cells. These viral vector vaccines can infect the host’s cells but cannot spread within the host. The FMDV P1-2A + 3C proteins are expressed from the vector within the infected cells and thus produce intracellular empty capsid particles. c Defective FMDVs, lacking the Lb coding sequence (c.f. Fig. 1), have been shown to be attenuated in animals and thus can be used to grow FMDV antigen in BHK cells more safely, as infectious virus. It is still expected that the virus will be inactivated prior to use as vaccine, as for current vaccines