Abortive infection of F-plasmid-containing Escherichia coli cells by bacterial virus T7 is determined by the right end of T7 gene 1.

Phage T7 infects male (F-plasmid-carrying) Escherichia coli cells abortively, whereas the closely related phage T3 grows normally. The inability or ability of phage to replicate in male host cells depends on whether the right end of gene 1 (coding for the phage-specific RNA polymerase) consists of T7 or T3 DNA base sequences.