Investigation of cytomegalovirus and human herpes viruses 6 and 7 as possible causative antigens in psoriasis

Psoriasis is probably a T-cell-mediated autoimmune disease. Infectious models of autoimmune diseases have been proposed and in psoriasis, it has been suggested that there may be molecular mimicry between streptococcal antigens and epidermal keratins. The immunological profile of stable psoriasis plaques suggests, however, that viral antigens may be important. We investigated, using polymerase chain reaction techniques, whether DNA from either cytomegalovirus (CMV) or human herpes viruses (HHV) 6 and 7 is present in the skin of patients (n = 10) with chronic plaque psoriasis. We also investigated 29 patients for the presence of serum IgG to CMV. We found no evidence of CMV or HHV 7 DNA in psoriasis plaques although DNA for HHV 6 was detected in both involved and uninvolved skin in 1 out of 10 patients. There was no statistically significant increase in prior CMV infection, as assessed by the presence or absence of serum IgG to CMV, in psoriasis, compared to our local population. Although there is circumstantial evidence that viral antigens may be important in the pathogenesis of psoriasis we found no evidence to link infection with CMV or HHV 6 and 7 with subsequent development of chronic plaque psoriasis.