Research | Valganciclovir review of subset of CFS patients by Montoya and others | 10 October 2012

Published online by the Journal of Medical Virology, 10 October 2012

Response to valganciclovir in chronic fatigue syndrome patients with human herpesvirus 6 and Epstein–Barr virus IgG antibody titers†‡

Tessa Watt (1,§), Stephanie Oberfoell(1,¶), Raymond Balise(2), Mitchell R. Lunn(3,‖), Aroop K. Kar(1), Lindsey Merrihew(1), Munveer S. Bhangoo1(††), José G. Montoya(1,2,4,*)

(1) Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University Medical Center, Palo Alto, California
(2) Stanford University School of Medicine, Health Research and Policy, Stanford, California
(3) Stanford University School of Medicine, Stanford, California
(4) Palo Alto Medical Foundation, Research Institute, Palo Alto, California
(§,5) University of Michigan Medical School, 1301 Catherine Road, Ann Arbor, MI 48109.
(¶) Los Angeles David Geffen School of Medicine, University of California, 1633 Bruin Street, Los Angeles, CA 90047.
(‖) Department of Medicine, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115.
(††) San Diego School of Medicine, University of California, 8950 Villa La Jolla Drive, San Diego, CA 92037.
Email: José G. Montoya (
*Stanford University School of Medicine, 300 Pasteur Drive, Room S-101, Stanford, CA 94305.
† Author contributions: T.W., S.O., A.K.K., and J.G.M. designed the study. M.R.L. and J.G.M. provided patient care. T.W., S.O., A.K.K, and M.B. coordinated the study and collected the data. T.W., S.O., and R.B. performed statistical analysis and analyzed the data. T.W., S.O., R.B., M.R.L., L.M., and J.G.M. wrote the manuscript. J.G.M. supervised the project.
‡ All authors have no financial or other conflict of interest.


Valganciclovir has been reported to improve physical and cognitive symptoms in patients with chronic fatigue syndrome (CFS) with elevated human herpesvirus 6 (HHV-6) and Epstein–Barr virus (EBV) IgG antibody titers. This study investigated whether antibody titers against HHV-6 and EBV were associated with clinical response to valganciclovir in a subset of CFS patients.

An uncontrolled, unblinded retrospective chart review was performed on 61 CFS patients treated with 900 mg valganciclovir daily (55 of whom took an induction dose of 1,800 mg daily for the first 3 weeks). Antibody titers were considered high if HHV-6 IgG ≥1:320, EBV viral capsid antigen (VCA) IgG ≥1:640, and EBV early antigen (EA) IgG ≥1:160. Patients self-rated physical and cognitive functioning as a percentage of their functioning prior to illness.

Patients were categorized as responders if they experienced at least 30% improvement in physical and/or cognitive functioning. Thirty-two patients (52%) were categorized as responders. Among these, 19 patients (59%) responded physically and 26 patients (81%) responded cognitively. Baseline antibody titers showed no significant association with response.

After treatment, the average change in physical and cognitive functioning levels for all patients was +19% and +23%, respectively (P < 0.0001). Longer treatment was associated with improved response (P = 0.0002). No significant difference was found between responders and non-responders among other variables analyzed. Valganciclovir treatment, independent of the baseline antibody titers, was associated with self-rated improvement in physical and cognitive functioning for CFS patients who had positive HHV-6 and/or EBV serologies. Longer valganciclovir treatment correlated with an improved response.


0344 576 5326

Available every day of the week between these times: 10am - 12noon, 2pm - 4pm and 7pm - 9pm.

Calls cost the same as other standard landline numbers (starting 01 or 02). If you have a call package for your landline or mobile phone then calls will normally come out of your inclusive minutes.