Association analysis between symptomology and herpesvirus IgG antibody concentrations in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and multiple sclerosis

Abstract

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and multiple sclerosis (MS) are two complex and multifactorial diseases whose patients experience persistent fatigue, cognitive impairment, among other shared symptoms. The onset of these diseases has also been linked to acute herpesvirus infections or their reactivations. In this work, we re-analyzed a previously-described dataset related to IgG antibody responses to 6 herpesviruses (CMV - cytomegalovirus; EBV - Epstein-Barr virus; HHV6 - human herpesvirus-6; HSV1 and HSV2 - herpes simplex virus-1 and -2, respectively; VZV - varicella-zoster virus) from the United Kingdom ME/CFS biobank. The primary goal was to report the underlying symptomology and its association with herpesvirus IgG antibodies using data from 4 disease-trigger-based subgroups of ME/CFS patients (n = 222) and patients with MS (n = 46). The secondary objective was to assess whether serological data could distinguish ME/CFS and its subgroup from MS using a SuperLearner (SL) algorithm. There was evidence for a significant negative association between temporary eye insight disturbance and CMV antibody concentrations and for a significant positive association between bladder problems and EBV antibody concentrations in the MS group. In the ME/CFS or its subgroups, the most significant antibody-symptom association was obtained for increasing HSV1 antibody concentration and brain fog, a finding in line with a negative impact of HSV1 exposure on cognitive outcomes in both healthy and disease conditions. There was also evidence for a higher number of significant antibody-symptom associations in the MS group than in the ME/CFS group. When we combined all the serological data in an SL algorithm, we could distinguish three ME/CFS subgroups (unknown disease trigger, non-infection trigger, and an infection disease trigger confirmed in the lab at the time of the event) from the MS group. However, we could not find the same for the remaining ME/CFS group (related to an unconfirmed infection disease). In conclusion, IgG antibody data explains more the symptomology of MS patients than the one of ME/CFS patients. Given the fluctuating nature of symptoms in ME/CFS patients, the clinical implication of these findings remains to be determined with a longitudinal study. This study is likely to ascertain the robustness of the associations during natural disease course.

Keywords: Cytomegalovirus; Enzyme-linked immunosorbent assay; Epstein-barr virus; Herpes simplex virus-1 and -2; Human herpesvirus-6; SuperLearner; United Kingdom ME/CFS biobank; Varicella-zoster virus.

Fig. 1

Age-adjusted odds ratios (dots) ordered by magnitude and their Bonferroni-adjusted 95% confidence intervals (horizontal bars) for the presence of each of 48 symptoms when comparing the whole ME/CFS group to the MS group (reference). White-filled dots refer to symptoms where there was evidence of a higher frequency in the ME/CFS group than in the MS group. Grey-filled dots refer to symptoms where there was evidence for the same frequency in both cohorts.

Fig. 2

Age-adjusted odds ratios (dots) and their Bonferroni-adjusted 95% confidence intervals (horizontal bars) for the presence of each of 48 symptoms when comparing ME/CFS_S0 (A), ME/CFS_S1 (B), ME/CFS_S2 (C), and ME/CFS_S3 (D) to the MS group. The “*” symbol in some of the bars denotes an upper limit beyond the maximum value used for the xx axis. See Fig. 1 legend for further information.

Fig. 3

ROC curves for the predictions based on an SL algorithm trained with 4 different classifiers (Elastic-Net Logistic Regression, Linear Discriminant Analysis, Quadratic Discriminant Analysis, and Random Forest) and 10-fold cross-validation using antibody data and patients with MS as the controls. Optimal sensitivities and specificities were estimated at 0.619 and 0.725 for ME/CFS_S0, 0.512 and 0.925 for ME/CFS_S1, 0.772 and 0.075 for ME/CFS_S2, 0.375 and 0.950 for ME/CFS_S3, when compared to the MS group.

Fig. 4

Smooth-line approximations (green lines) of the relationship between log₂(antibody concentrations) and SL-estimated probability of ME/CFS_S1 patient when compared to patients with MS (A – CMV, B – EBV-EBNA1, C – EBV-VCA, D – HHV-6, E – HSV1, F – HSV2, G – VZV). In the plots, each dot represents a patient and the vertical dashed line represents the cut-off value for seropositivity according to the respective lab protocol.

Fig. 5

Association analysis between symptoms and IgG antibody data for the MS group (A), the overall ME/CFS (B), the ME/CFS_S0 subgroup (C), ME/CFS_S1 subgroup (D), ME/CFS_S2 subgroup (E), and ME/CFS_S1 subgroup (F), where the xx axis refers to log₂(mean fold-change) between individuals with and without a given symptom, respectively, and the yy axis refers to the logarithm in base 10 of the p-values derived from the Mann-Whitney test and adjusted for an FDR of 5% using the Benjamini-Hochberg procedure (-log₁₀(p_BH)). See Supplementary Table S1 for linking the symptom codes presented in each plot to the respective symptom descriptions.