Little is known about the role that O-antigen modification plays in addition to generating antigenic variation. We are studying the effect that it and the serotype-converting phages have on the virulence characteristics of S. flexneri. We have isolated and partially characterised several serotype-converting phages from different S. flexneri serotype strains. We have sequenced the genome of bacteriophage SfV, which encodes the factors involved in type V O-antigen modification.
Functional studies are now being carried out on various gene modules identified on SfV (including O-antigen modification and lytic gene cassettes) and other serotype-converting bacteriophages of S. flexneri.