Lack of inhibitory sequences in the first 30 nucleotides of the HPV-16 L1 gene. (A) Structures of the indicated expression plasmids. pCL130EIAV contains the first 30 nucleotides of the HPV-16 L1 gene fused in frame with the EIAV p55gag coding sequence, and pCEIAV30L1 contains the first 30 nucleotides of the EIAV p55gag fused in frame with the HPV-16 L1 coding sequence. (B) Northern blot of total cytoplasmic RNA harvested from HeLa cells transfected with the plasmids shown in panel A. Plasmid pCTAT (42), expressing the HIV-1 tat cDNA (33), was included as an internal control for transfection efficiency. L1, HPV-16 L1 gene; EIAV, the EIAV p55gag coding sequence; NRE, negative regulatory element in the HPV-16 late 3′ UTR from nucleotide 7282 to 7453 (35).