M13KO7 helper phage is suitable for use with M13/phagemid hosts for production from vectors containing f1 or f1 origin of replication ssDNA. This high-titer helper phage was prepared by modifying the Vieira and Messing procedures (1), eliminating the need to separately reserve and maintain independent helper phage. It contains the Km^r gene and the p15A replication source, allowing it to replicate like an intracellular plasmid. Detailed protocols for ss DNA production are included on the product map. M13KO7 helper phage provides:

• Conveniently prepare ss DNA from M13 or phagemid vectors
• >1 x 10¹¹ pfu/ml