PubMed · 13941102
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K PAIGEN, H WEINFELD. 1963. Cooperative infection by hostmodified lambda phage.. https://doi.org/10.1016/0042-6822(63)90052-7
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The stability of whole bacteriophage lambda particles, used as a DNA vaccine delivery system has been examined. Phage were found to be highly stable under normal storage conditions. In liquid suspension, no decrease in titre was observed over a 6-month period at 4 and -70 degrees C, and phage stability was unaffected by freeze/thawing. The measured half life of phage in suspension was 36 days at 20 degrees C, 3.4 days at 37 degrees C and 2.3 days at 42 degrees C. Freeze drying of a phage suspension (with or without the stabilizers dry skim milk or trehalose) resulted in 5-20% residual viability. Following desiccation (with or without stabilizers), measured half lives ranged from 20 to 100 days at 20 degrees C, 2.6 to 38 days at 37 degrees C, 2.1 to 26 days at 42 degrees C, 7 to 33 h at 70 degrees C, and 1.3 to 6m at 100 degrees C. In all cases the addition of trehalose significantly increased the stability of the desiccated phage. When stored at -70 degrees C, desiccated phage appeared to be stable in the absence of stabilizers. When phage lambda was diluted into water, a marginal loss in titre was observed over a 2-week period. Over a 24 h period, liquid phage suspensions were stable within the pH range pH 3-11, therefore oral administration of bacteriophage DNA vaccines via drinking water may be possible.
Rho-dependent transcription termination at the phage lambda tR1 terminator is governed primarily by the upstream rut element that encodes two RNA regions rutA and rutB. The two regions are separated by the boxB RNA motif, which is believed to be dispensable for Rho activity but serves as a binding site for lambda N protein in the antitermination process. By using a minimal in vivo termination system, we show that the intervening boxB RNA motif has a double function in the mechanisms of termination/antitermination at lambdatR1. As a folded hairpin structure, it acts as a clamp that holds rutA and rutB side by side for optimal interactions with Rho leading to efficient termination. Conversely, the binding of N protein to boxB induces antitermination at lambdatR1 by preventing access of Rho to the rut sequences. This dual role was clearly shown in vivo by studying the effects of multiple mutations within the boxB hairpin stem on transcription termination and by substituting the N/boxB couple with the unrelated coat protein of phage MS2 and its stem-loop RNA binding site.
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