Valaciclovir therapy for secondary suppression of immune response to herpesviruses: An exploratory study

Herpesviruses establish a state of persistent infection which is suppressed by sustained virus-specific immune control. The magnitude of this immune response can increase with age and lead to attrition of immune reserve against other pathogens. Approaches which suppress herpesvirus-specific immunity may therefore have the potential to improve general immune function. Anti-retroviral therapy for HIV leads to a reduction in HIV viral antigen and has been shown to mediate a secondary attenuation of the HIV-specific immune response. As such, we assessed if treatment with valaciclovir could suppress the immune response against cytomegalovirus and Epstein Barr Virus in donors aged >65 years. Medication was given at 3 different doses up to a maximum of 4gm/day for 6 months and humoral and cellular profiles were assessed over 12 months. Anti-viral therapy did not impact on the magnitude or phenotype of the humoral or cellular virus-specific immune response during the study period. Treatment also had no impact of physical or mental quality of life assessment. These data show that valaciclovir treatment, at this dose and treatment duration, does not attenuate the CMV or EBV-specific immune response in this age group.