Comparison of the locations of homologous fowlpox and vaccinia virus genes reveals major genome reorganization.

We have derived a restriction enzyme map for the fowlpox virus FP9 strain. Sites for BamHI, PvuII, PstI and NcoI have been mapped mainly by Southern blotting. The size of the genome derived from the restriction maps (254 kb) corresponds to the figure of 260 +/- 8 kb determined from analysis of genomic DNA by pulsed-field electrophoresis. The map can be compared with a previously published map for a different strain of fowlpox virus using the PstI digest which is common to both studies. Some 65 kb of fowlpox virus sequence, in 11 blocks, as well as individual M13 clones have been aligned with the map. Where those blocks correspond with blocks of homologous genes in vaccinia virus, it is possible to compare the genomic locations for those genes in the two viruses. This comparison reveals that, whereas there are blocks of sequence within which genes exist in the same relative position in the two viruses, the genomic location of those sequence blocks differs widely between the two viruses.