HUMAN-HERPESVIRUS-7 IN PATIENTS WITH PITYRIASIS-ROSEA - ELECTRON-MICROSCOPY INVESTIGATIONS AND POLYMERASE CHAIN-REACTION IN MONONUCLEAR-CELLS, PLASMA AND SKIN

Background: Clinical evidence suggests a viral etiology for pityriasis rosea (PR). Objective: To evaluate human herpesvirus (HHV)-6 and HHV- 7 as candidates for the etiology of PR. Methods: Blood and skin tissue from 12 patients with acute PR, and 12 patients with other der matose s were studied, as well as blood samples from 25 healthy persons. Seru m interferon (IFN)-alpha and IFN-gamma were analysed by ELISA. Analysi s of morphological changes in cocultured peripheral blood mononuclear cells (PBMC) and electron microscopy (EM) to identify viral particles were performed, Polymerase chain reaction (PCR) with specific primers for HHV-6 and HHV-7 DNA sequences was performed on the plasma and PBMC of patients and healthy controls and on the skin of patients with PR and other skin diseases. Results: PR plasma contained detectable IFN-a lpha and IFN-gamma, whereas plasma from controls did not. PBMC from PR patients showed ballooning cells and syncytia after 7 days in culture whereas PBMC from controls and recovered PR patients did not. This cy topathic effect was also documented in a PR patient who relapsed and i n Sup-T1 cell cultures inoculated with the cell-free supernatant from centrifuged cultured PBMC; in this supernatant, herpesvirus virions we re detected by EM. PCR identified HHV-7 DNA in PBMC, plasma and skin f rom all patients with active PR and in the PBMC only of 5 patients tes ted 10-14 months later. Weaker signals of HHV-7 DNA were detected in P BMC of 11 controls, but not in their plasma. Skin was negative for HHV -7 in all control specimens. Conclusions: Although the detection of HH V-7 DNA in PBMC and tissues does not prove directly a causal role, HHV -7 DNA in cell-free plasma corresponds to active replication which sup ports a causal relationship. We propose that PR is a clinical presenta tion of HHV-7 reactivation.