ABSTRACT
This chapter describes some biology of vaccinia virus, and how vaccinia virus recombinant is made, and discusses their potential application as new live vaccines. The strategy used to construct vaccinia virus recombinants reflects some unusual properties of the virus and it is therefore necessary to consider these before describing how the recombinant viruses are made. Vaccinia virus gene expression is principally controlled at the transcriptional level although more subtle translational controls may be involved. The large size of the vaccinia virus genome and its noninfectious nature, when stripped of transcriptional enzymes, make construction of recombinant genomes in vitro impracticable. This absence of data reflects the caution in testing recombinant vaccinia viruses in humans until the foreign genes are inserted into vaccine strains of vaccinia virus and until expression and presentation of the foreign antigens have been optimized. The location of the antigen within an infected cell is also an important factor influencing immunogenicity.
