Fig. 3.

Effect of SaPI interference genes on phage 80α. Phage platings were as in Fig. 1A. (A) Effect of SaPI1 CpmAB. (B) Effects of SaPI2 and SaPIbov1 CpmAB and Ppi. Note that ORF13 was always included in deletions of SaPI2 cpmAB because a deletion of the two genes alone could not be constructed. ORF13 does not affect interference. (C) Agarose gel analysis of DNA extracted from sedimented phage particles. Phage 80α was grown on RN4220 and various derivatives of SaPI2 (i; Upper) or SaPI1 (ii; Lower). The resulting lysates were treated with DNase, PEG-precipitated, and phenol extracted. Equivalent amounts of DNA were separated on 0.8% agarose gel for 13 h at 60 V, strained with ethidium bromide, and photographed.