Kinetics of cytokine and chemokine responses in patients with primary human herpesvirus 6 infection

Background: Cytokines and chemokines induced by human herpesvirus 6 (HHV-6) infection may play an important role in the observed HHV-6-associated clinical complications. However, basic data for cytokine and chemokine synthesis in primary HHV-6 infected patient without complication is lacking. Objective: Aim of this study was to elucidate basic kinetic data for expressions of cytokines and chemokines in patients with primary HHV-6 infection without complication. Study design: Twenty-six patients suffering from fever were enrolled in this study. Fourteen biomarkers were measured in 74 serially collected sera samples from 26 patients. Additionally, serum samples obtained from 14 healthy children were used for control. Results: Twenty of the 26 patients were diagnosed with primary HHV-6 infection based on viral isolation and serological analysis. The mean age (P= 0.1289) and proportion of males to females (P= 0.9999) between the patients with and without primary HHV-6 infection were not statistically different. At the acute phase of the disease, three cytokines (IFN-γ; P= 0.0046, IL-2; P= 0.0366, and IL-4; P= 0.0255) and one chemokine (MCP-1; P= 0.0019) were significantly higher in patients with primary HHV-6 infection compared to those without infection. Interleukin-5 levels during the convalescent period were significantly higher in patients with HHV-6 infection (P= 0.0205). By 1 month post-infection, cytokine and chemokine expression had returned to almost basal levels. Conclusion: As suggested by the previous in vitro studies, present in vivo analysis also suggests that HHV-6 has potency for induction of cytokines and chemokines.