Location of a new endonuclease restriction site associated with a temperature-sensitive mutation of vaccinia virus

The novel EcoRI recognition site at the temperature-sensitive locus of ts 9251, derived from vaccinia IHD-W, has been mapped on the poxvirus genome. Using Southern blot hybridization, it was demonstrated that the EcoRI fragment D of vaccinia IHD-W and of rabbit poxvirus were identical in terms of sequence and presumed map position and that the novel restriction site found in ts 9251 occurred at a point 28 megadaltons from the right terminus of the molecule. This study reveals the first identification of a poxvirus mutation on the physical map and provides a potential marker for further, genetic mapping of temperature-sensitive mutations of vaccinia and related poxviruses.