FIG. 1.

(A) Schematic diagram of the HPV-16 genome. Early and late viral promoters p97 and p670 are indicated. Numbers indicate the nucleotide positions of 5′ splice sites (filled circles), 3′ splice sites (empty circles), or early and late poly(A) signals pAE and pAL, respectively. (B) Potential HPV-16 mRNAs representing major early mRNA (E4 mRNA) and late mRNAs (L1 and L2/L1 mRNAs). Previously identified splicing regulatory elements are indicated, including a major splicing enhancer downstream of SA3358 (44), splicing suppressor sequences at SD3632 (44), and multiple splicing silencers in the L1 coding region that suppress the use of SA5639 (58, 61). Polyadenylation regulatory elements in the early UTR (59) and in the L2 region (41) are indicated. U-shaped arrows indicate positive (+) or negative (−) effects of previously identified regulatory RNA elements on viral splice sites (44, 61). LCR, long control region.