High viral load of human wart-associated papillomaviruses (PV) but not beta-PV in cutaneous warts independent of immunosuppression.

Background: A broad spectrum of human papillomaviruses (HPV) has been detected in warts from immunocompetent patients and a much more diverse range from immunosuppressed organ transplant recipients (OTR).
Objectives: To determine the HPV types in warts from OTR, we assessed present infections of mucosal (alpha-PV), wart-associated (alpha-, micro- and nu-PV) and cutaneous HPV types (beta-/gamma-PV) in immunocompetent patients and OTR. Patients/methods Forty-one warts from 29 immunocompetent patients (non-OTR) and 53 warts from 33 OTR were analysed for DNA of human alpha-, beta-, gamma-, micro- and nu-PV. For frequent types viral load was determined by quantitative real-time PCR.
Results: Compared with non-OTR prevalence of cutaneous HPV (79% vs. 49%, P < 0.01) and the number of multiple infections (62% vs. 17%, P < 0.0001) were significantly increased. The mean viral load of the wart-associated HPV was more than 10(5)-fold higher compared with human beta-PV in both cohorts.
Conclusions: The high load of wart-associated HPV suggests an active role of these viruses rather than cutaneous types in warts independent of immunosuppression; however, the substantial fraction of warts with low HPV genome copies remains to be explained.