Early functional mutants of . . . coliphage lambda.

The early functional mutants of lambda, belonging to cistrons N, O, and P, are known to be blocked prior to vegetative multiplication of the lambda genome. Superinfection of heteroimmune defective lysogens by these mutants failed to elicit the function required for replication of the superinfecting phage. The mutants among themselves also showed poor cooperation on a nonpermissive host. Studies on the effects of different multiplicities of infection for bacterial lysis showed identical responses for mutants of different cistrons.