FIG 5 .
PIPEF swapping alters phage tropism. (A) Using the E. faecalis strain E1Sol, which is naturally resistant to infection by φVPE25, both cross streak and plaque assays showed that E1Sol can acquire φVPE25 susceptibility by expressing the E. faecalis V583 PIPEF gene (pLZPIP). Single-copy replacement of the E. faecalis E1Sol PIPEF homolog with V583 PIPEF in the E1Sol chromosome also confers φVPE25 sensitivity (PIPV583). A chimera of E. faecalis E1Sol PIPEF and the variable region of V583 PIPEF show that the PIPEF variable region determines phage tropism (pLZEV). (B and C) Plaquing efficiency of φVPE25 (B) and φVFW (C) on E. faecalis V583, E1Sol, and PIPV583 transgenic E1Sol strains. The value that was significantly different (P < 0.01) by Student’s t test from the value for E. faecalis V583 is indicated by an asterisk. (D) Cross streak assay showing that expression of E. faecalis V583 PIPEF from plasmid pPBPIP can confer φVPE25 sensitivity on E. faecium strains 1,141,733 and Com12, but not strain Com15.