FIG. 2.

Genetic stability of recombinant PVs. Each recombinant PV, containing a different foreign insert, was tested for genetic stability by RT-PCR and Western blot during consecutive passages in HeLa cell monolayers. (A) RT-PCR patterns of recombinant PVs during consecutive passages. Recombinant PVs were categorized into three groups based on the patterns of insert stability described in the text. The symbol in parentheses next to the name of each insert represents the group to which it belongs (described in Fig. 3) and the insert specificity, described in Table 1. Lanes: M, 100-bp ladder size markers; S, poliovirus Sabin 1; R, RPS-Vax vector-derived virus; C, insert-containing recombinant plasmid. The numbers indicate the passage cycle of each recombinant PV. The bar and arrowhead indicate the original and truncated forms of the inserts, respectively. (B) Passage stability of the recombinant PVs examined for insert expression by Western blot. The numbers indicate the passage cycle of the recombinant PV to be infected into HeLa cells. Recombinant PV-infected HeLa cell lysates and control SIV (C) were screened by Western blotting with monkey anti-SIV serum. Arrows indicate the wild-type (wt) p27 of SIV and recombinant p27 expressed from recombinant PV.