A new filamentous phage cloning vector: fd-tet.

We have constructed a hybrid chromosome composed of the genome of wild-type fd (a filamentous, male-specific bacteriophage) and a segment of transposon Tn10 coding for tetracycline resistance but not including the Tn10 insertion sequences. The hybrid phage infects male E. coli, thereby transducing the infected cells to tetracycline resistance. The phage DNA can also be propagated in F- cells after transfection. This new phage, fd-tet, may be used as a cloning vector to produce large quantities of cloned DNA in single-stranded form. Its usefulness has been demonstrated by cloning of a fragment from bacteriophage lambda. Some unexpected sequence alterations have been identified in lambda cloning experiments.