The Pif system (Phage Inhibition by F factors) was first described by Morisson & Malamy :ref{doi=10.1038/newbio231037a0}. The Pif region of the F plasmid inhibits the phage T7 through abortive infection :ref{doi=10.1038/newbio231037a0,10.1007/BF00327934}.
## Molecular mechanisms
PifA was later identified as the effector of the abortive infection :ref{doi=10.1128/jb.173.20.6507-6514.1991,10.1016/j.virol.2004.06.001} through nucleotide depletion by increased membrane permeability (also known as "leakage").
## Example of genomic structure
The Pif system is composed of 2 proteins: PifC and, PifA.
The Pif system is composed of 2 proteins: PifC and PifA.