High viral load of human wart-associated papillomaviruses (PV) but not β-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 (α-PV), wart-associated (α-, μ- and ν-PV) and cutaneous HPV types (β-/γ-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 α-, β-, γ-, μ- and ν-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 10⁵-fold higher compared with human β-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.