FIG. 4.

Bacteria are not lysed by VP5* expression. (A) β-Galactosidase is not released following VP5* expression. E. coli BL21(DE3)/pLysS containing the pET-6HIS plasmid with no insert or expressing either VP5*(265–474) or VP5*(248–776) were assayed for their ability to cause the release of β-galactosidase into the culture medium as measured by ONPG cleavage. Bacteria were grown to an OD₆₀₀ of 0.2 to 0.4 and induced by the addition of IPTG (1 mM). Samples of each culture were removed at the indicated times after IPTG induction, and the OD₆₀₀ was measured. Cells were pelleted, and both resuspended cells and supernatants were analyzed for ONPG cleavage as in Fig. 1. This experiment was repeated two times with similar results. (B) VP5* expression does not alter bacterial growth. E. coli BL21(DE3)/pLysS transformed with pET-6HIS plasmids expressing either VP5*(265–474), VP5*, or VP8* were grown to an OD₆₀₀ of 0.2 to 0.4 and split into separate tubes. One tube was induced by the addition of IPTG (1 mM), and another was grown in parallel as a control. At given times postinduction, samples of each culture were removed and the OD₆₀₀ was measured; growth curves of induced and uninduced cultures are shown. This experiment was repeated three times with similar results.