Epstein-Barr virus (EBV) antibody changes over time in a general population cohort in rural Uganda, 1992-2008

Abstract

Background: Epstein-Barr virus (EBV) infection is ubiquitous and in sub-Saharan Africa, occurs early in life. In a population-based rural African cohort, we leveraged historical samples from the General Population Cohort (GPC) in Uganda to examine the epidemiology of infection with EBV over time, in the era of HIV.

Methods: We used 9024 serum samples collected from the GPC in 1992, 2000, 2008, from 7576 participants across the age range (0-99 years of age) and tested for anti-EBV immunoglobulin G (IgG) antibodies to EAd, VCA, and EBNA-1 using a multiplex bead-based assay. The related gammaherpesvirus, Kaposi's sarcoma-associated herpesvirus (KSHV) seropositivity was also determined by detection of anti-KSHV IgG antibodies to K8.1 or ORF73 measured by recombinant protein enzyme-linked immunosorbent assay. Data on sex, age, and HIV serostatus were also collected. EBV seropositivity was modeled with age (excluding those under one year, who may have had maternal antibodies), sex, HIV serostatus, and KSHV serostatus using generalized linear mixed effects models to produce beta estimates.

Results: More than 93% of children were EBV seropositive by one year of age. EBV seropositivity was significantly associated with KSHV seropositivity. Anti-EBNA-1 antibody levels decreased with increasing age and were lower on average in people living with HIV. In general, anti-EAd antibody levels increased with age, were higher in males and KSHV seropositive persons, but decreased over calendar time. Anti-VCA antibody levels increased with age and with calendar time and were higher in KSHV seropositive persons but lower in males.

Conclusions: This is the first study to identify factors associated with EBV antibodies across the entire life-course in rural sub-Saharan Africa. Consistent with other studies, EBV was near ubiquitous in the population by age one year. Patterns of antibodies show changes by age, sex and calendar time, but no association with HIV was evident, suggesting no relationship between EBV sero-epidemiology and the spread of HIV in the population over time in Uganda.

Keywords: Antibodies; Epstein–Barr virus (EBV); HIV; Kaposi’s sarcoma-associated herpesvirus (KSHV); Life course; Pre-ART; Serology; Sub-Saharan Africa; Uganda.

Fig. 1

Average log(MFI) anti-EBV antibody levels by age in years. Mean (•) and standard deviation ($⊢$) median fluorescence intensities (MFI) of anti-Epstein–Barr Virus (EBV) log-transformed antibody levels by age in years for A EBV-nuclear antigen (EBNA-1), B early antigen (EAd), C viral capsid antigen (VCA), and D EBV Seropositivity by age in years. EBV seropositivity was measured as detection of anti-EBV antibodies to EBNA-1, EAd, or VCA

Fig. 2

Age and Cohort-specific anti-EBV antibody levels. A Age effects average anti-EBV antibody levels by enrollment year and B Enrollment cohort-specific average anti-EBV antibody levels by age group. All antibody levels were log transformed

Fig. 3

Risk Factors for anti-EBV antibody levels in EBV seropositive participants aged > 1 year. Antibody levels were measured in serum of 8495 samples from 7150 EBV seropositive participants over 1 year of age and reported as median fluorescence intensities (MFI) which were log transformed. CD4 T cell and WHO HIV Disease Stage analyses included 307 samples from 273 participants and 338 samples from 268 participants, respectively. Linear mixed effects regression modelling was used to estimate the average difference in log transformed antibody levels between groups. For age treated as a continuous variable the estimate represents the average change in log transformed antibody levels for every one-year increase in age. For CD4 T cell count the estimates represent the average change in log transformed antibody levels for every 100-cell increase in CD4 T cell counts/mm³. Beta coefficients (•) and 95% confidence intervals (95% CI) ($⊢$) are provided. All models included a random intercept and adjusted for all other co-factors. In adjusted models age was treated as continuous. For estimates refer to Additional file 1: Table S1. Other acronyms include: Human immunodeficiency virus (HIV), Kaposi’s sarcoma-associated herpesvirus (KSHV), World Health Organization (WHO)