OCCURRENCE OF HUMAN HERPESVIRUS-6A/B AND HUMAN HERPESVIRUS -7 IN MYALGIC ENCEPHALOMYELITIS/CHRONIC FATIGUE SYNDROME

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a multifactorial disorder with undefined cause and virus infection is believed to be one of ME/CFS potential triggers. The aim of the study was to determine occurrence of human herpesvirus (HHV)-6A/B and HHV-7 in patients with ME/CFS. 200 patients with clinically diagnosed ME/CFS and 150 apparently healthy individuals (controls) were included in the study. Single-round polymerase chain reaction (PCR), nested PCR, and quantitative real-time PCR were used to determine extracted DNA quality, detect the presence and load of HHV-6A/B and HHV-7. HHV-6A/B genomic sequences in DNA isolated from peripheral blood were detected in 53% of patients and 29% controls (persistent infection), in DNA isolated from cell free plasma (active infection) – in 11% of ME/CFS patients and none of controls (p < 0.0001), in 42% of patients and 29% of controls (p = 0.0133) infection was in latent phase. In patients with latent HHV-6A/B infection median (IQR) HHV-6 load was 279 (1022–54.5) copies/10^6 cells, with active infection – 1927 (6732–348.5) copies/10^6 cells (p = 0.0019). Six patients’ HHV-6A/B load was 1209033 (1464421–808183) copies/10^6 cells. Markers of persistent HHV-7 infection were revealed in 92% of ME/CFS patients and 75% of controls (p =
0.0766), active HHV-7 infection in – 34% of patients and 8% of controls (p < 0.0001), though in 58% of ME/CFS patients and 67% controls (p = 0.0766) infection was in latent phase. In ME/CFS patients with latent HHV-7 infection load was 196.7 (533–132) copies/10^6 cells and with active infection – 238.6 (410.6–80.2) copies/10^6 cells (p = 0.3502). In one patient with ME/CFS HHV-7 load was 1140127.6 copies/10^6 cells. Persistent HHV-6A/B and HHV-7 infection in an active phase is presented significantly more frequently and with a higher viral load among patients with ME/CFS than controls.