Vaccinia virus DNA replication: A short review

The purpose of this review is to summarize information published since 1990 on DNA replication, recombination and repair of vaccinia virus, a poxvirus. Temperature-sensitive mutations reveal four essential genes related to viral DNA replication: the E9L DNA polymerase, BIR protein kinase, D5R protein, and D4R uracil DNA glycosylase. Other proteins are likely to be also involved in viral DNA replication: the H6R DNA topoisomerase, I3L single stranded-DNA binding protein, H5R virosome-associated protein, and A50R DNA ligase. In addition, several viral-encoded proteins do regulate the level of the deoxyribonucleoside triphosphate pool: the J2R thymidine kinase, A48R thymidylate kinase, I4L and F4L subunits of ribonucleotide reductase, and F2L dUTPase. Despite the apparent simplicity of the mechanism of vaccinia virus DNA replication, several important questions related to the three Rs remain unsolved.