Interferon resistance is independent from copy numbers in benign HPV-induced lesions

Interferons (IFNs) are successfully used in treatment of different human papillomavirus (HPV)-related diseases, such as condyloma acuminatum. Unresponsiveness can be seen in a number of patients which is related to a differential expression of early (E7) and late (L1) viral genes, according to our preliminary studies rather than to impaired IFN-signalling. The molecular basis for this differential expression might imply differential viral replication (copy numbers) in responder vs. nonresponder patients. PCR analysis revealed that the two groups did not differ significantly in HPV copy numbers before treatment. In contrast E7 and L1 levels significantly differed in responders versus nonresponders, regardless of copy numbers. Also, the IFN-mediated antiproliferative effect was mostly influenced by other factors rather than just the copy number. Our data imply that the unresponsiveness of certain patients to IFN treatment may relate to differential viral gene transcription rather than different copy numbers of infecting HIVs.