1. Inoculate a single colony of host strain XL1-Blue (MRF) into 5 ml LB containing 12.5 mg/ml tetracycline.

2. Incubate at 37°C for 1 hour with shaking.

3. Add 1 m helper phage (VCSM13 or RE704) or pick from single plaques.

4. Incubate at 37 °C for 1 hour.

5. Add kanamycin to a final concentration of 25 mg/ml.

6. Grow at 37 °C for 8 hours to overnight with shaking.

7. Pellet cell debris by centrifugation.

8. Aliquot the supernatant, titer and store at -20°C.