FIG. 7.

Summary of RT binding activities of HBV ɛ RNA mutants. Left. The wild-type (long) HBV ɛ sequences are shown at the top, with the lower-stem, bulge, upper-stem, and loop structural elements indicated. Deletions are denoted by the dots at the appropriate positions, and substitutions are indicated by lowercase, bold, and underlined lettering. Middle. The RNA mutants are schematized in the secondary-structure model. Deletions are denoted by dotted lines and substitutions by thick lines. Right. RT binding activities of the ɛ RNAs are summarized. The following symbols are used to indicate the RT binding activity: ++, 50 to 100% of wild-type activity; +, 10 to 50%; +/−, <10%; −, undetectable activity. The RNA packaging activities of the various ɛ mutants are taken from the literature (see Discussion for details). **, DNA synthesis is blocked; ***, deduced from the RNA selection study; ?, no effect on pgRNA packaging though defective in ɛ binding. The different degrees of shading and the numerals 1 to 4 are used to denote the classification of the ɛ mutants into four different groups (see Discussion for details).