FIG. 4.

Genetic stability of recombinant PVs expressing partial fragments of the HIV-1 (HXBc2) env gene. Partial fragments of the HIV-1 env gene were cloned into the RPS-Vax vector, resulting in production of recombinant PVs. (A) Coverage, G/C contents, and free energy of each env gene fragment are schematically illustrated. The solid box in the diagram indicates the major deletion site during the passages of the recombinant PV. The numbering of the 294 bp corresponds to the sequence from 787 to 1080 of the HIV-1 envelope (env). (B) RT-PCR patterns of partial env fragment-containing recombinant PVs during consecutive passages. Lanes: M, 100-bp size markers; S, poliovirus Sabin 1; R, RPS-Vax vector-derived virus; C, insert-containing recombinant plasmid. The numbers represent the passage cycle of each recombinant PV. The bar and arrow indicate the original and truncated forms of the insert, respectively.