Genome organization in hybrids between prophage phi 80 and Escherichia coli virus phi gamma

Prophage phi 80 is used for the detection of "discrete" viruses such as phage phi gamma by genetic recombination. Several genetic events have produced a series of hybrids which are currently being characterized. Characteristic genomic properties of the parent phages are recognized in these hybrids. "lambda"-type phages contain a cos-ended DNA of a single sequence, the size of which may be altered by hybridization. "gamma"-type phages contain DNA molecules of uniform size (about 52 kb) and of variable ends; their genome is able to promote highly efficient transduction (pug type) regardless of the origin of the right arm. In both hybrids, the att site is most often a junction point between the parental genomes due to common int-promoted recombination. New evidence is provided for the formation of viable heterozygous "lambda/gamma"-type bacteriophages.