Shigella flexneri hosts a temperate bacteriophage SfV responsible for the conversion of serotype Y strains (3,4) to serotype Sa (V; 3,4) through its glucosyl transferace gene. This enzyme mediated conversion effects a molecular antigenic conversion in glucosyl or glycosylic moiety attachment generating a corresponding immunogenic shift in the O-antigen component of the outer membrane lipopolysaccharide immune response among Shigellosis patients. With respect to vaccine development, further investigation into SfV's complete genome is crucial to explore and distinctly locate other genetic horizontal transfer contributing immunogenicity aside from the somatic antigen and proteins encoded by the invasion plasmid. SfV was placed in the group B of the Bradley classification scheme containing an approximate 39 kb intact DNA, double stranded, circularly permutted genome which appeared to be packaged by a headful mechanism at the Pac site. Bacteriophage SfV showed significant homology at the 2.5 kb fragment C serotype-conversion region of SfX but their morphology and protein profile were different. The construction of the physical map of SN in this study gives a concrete blueprint stipulating the orientation and size of its genome. This information is vital for further studies involving library construction, cloning, sequencing, amino acid expression and functional evaluation and homology studies.