FIG 1.

Stable expression of E6/E7 of HPV49 and HPV76 immortalizes primary HFKs. (A) Total RNA was extracted from HFKs transduced with the indicated retroviruses and subjected to retrotranscription. PCR was performed using different cDNAs as templates with HPV E7-specific primers. (B) Growth curve of HFKs (donor 1) expressing E6/E7 from the indicated HPVs. (C) Morphology of HFKs transduced with the indicated recombinant retroviruses at the indicated PDs. The same magnification (×20) was used for all the microphotographs. (D) Total RNA extracted from cells at the same passage was retrotranscribed and used as a template for RT–real-time PCR analysis of hTERT gene expression, normalized to GAPDH. Each result shown in the histogram represents the mean of results from three independent experiments performed in two donors (*, P < 0.05; ***, P < 0.005). (E) Total DNA was extracted from HFKs transduced with the indicated retroviruses and subjected to PCR using specific pLXSN primers recognizing regions immediately before and after the viral genes (top panel). Portions of these PCR products were used for a second PCR performed with HPV16 E7 primers (bottom panel).