[36] Use of minicells for bacteriophage-directed polypeptide synthesis

Phage infection of minicells provides a simple system to analyze the polypeptide (or RNA) products of a phage genome. In terms of this volume it is particularly important, as it provides a means to express in vivo the fragments of DNA cloned in λ vectors.39 Phage infection of minicells, as opposed to expression of plasmids in minicells, has the advantage of a zero time and that the minicells can be handled in a variety of ways, e.g., inducing or noninducing media, different temperatures, etc., before being required to express the phage DNA. In addition it is not necessary to construct a new minicell strain for each experiment as is the case in the expression of DNA cloned on plasmids. In terms of analysis of phage development, however, it should be remembered that significant differences exist between an infected cell and an infected minicell. Minicells are generally incapable of supporting significant amounts of phage DNA replication or producing progeny phage.17,28,37,40,41