title: Association of Epstein-Barr virus with systemic lupus erythematosus: effect modification by race, age, and cytotoxic T lymphocyte-associated antigen 4 genotype.
abstract: OBJECTIVE
  Epstein-Barr virus (EBV) is hypothesized to play a role in the development of systemic lupus erythematosus (SLE). Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is important in regulating T cell-mediated immunity, encompassing the first line of response to viral infections, and genetic variation in CTLA-4 has been associated with SLE. This study examined the seroprevalence of EBV in a population-based study of SLE patients from the southeastern United States, and potential interactions with CTLA-4 polymorphisms were assessed.
  
  
  METHODS
  Cases comprised 230 subjects recently diagnosed as having SLE (144 African American and 86 white) from university and community-based clinics, and controls comprised 276 age-, sex-, and state-matched subjects (72 African American and 204 white) recruited from driver's license registries. Antibodies to EBV capsid antigen were determined by enzyme-linked immunosorbent assay, with results expressed as positive or negative using the international standardized ratio (ISR) (a ratio of the sample absorbance to a known standard). CTLA-4 genotypes were identified by polymerase chain reaction-based methods.
  
  
  RESULTS
  In African Americans, EBV-IgA seroprevalence was strongly associated with SLE (odds ratio [OR] 5.6, 95% confidence interval [95% CI] 3.0-10.6). In whites, the modest association of SLE with EBV-IgA (OR 1.6) was modified by age, in that the strongest association was observed in those older than age 50 years (OR 4.1, 95% CI 1.6-10.4). The seroprevalence of EBV-IgM and that of EBV-IgG were not associated with SLE. Higher EBV-IgG absorbance ratios were observed in SLE patients, with a significant dose response across units of the ISR in African Americans (P < 0.0001). Allelic variation in the CTLA-4 gene promoter (-1661A/G) significantly modified the association between SLE and EBV-IgA (P = 0.03), with a stronger association among those with the -1661AA genotype.
  
  
  CONCLUSIONS
  These findings suggest that repeated or reactivated EBV infection, which results in increased EBV-IgA seroprevalence and higher IgG antibody titers, may be associated with SLE, and that the CTLA-4 genotype influences immune responsiveness to EBV in SLE patients. The observed patterns of effect modification by race, age, and CTLA-4 genotype should be examined in other studies and may help frame new hypotheses regarding the role of EBV in SLE etiology.
authors.affiliation: National Institute of Environmental Health Sciences, Durham, North Carolina, USA. cqp8@cdc.gov
authors.forename: Christine G
authors.initials: CG
authors.lastname: Parks
authors.forename: Glinda S
authors.initials: GS
authors.lastname: Cooper
authors.forename: Lori L
authors.initials: LL
authors.lastname: Hudson
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Dooley
authors.forename: Edward L
authors.initials: EL
authors.lastname: Treadwell
authors.forename: E W
authors.initials: EW
authors.lastname: St Clair
authors.forename: Gary S
authors.initials: GS
authors.lastname: Gilkeson
authors.forename: Janardan P
authors.initials: JP
authors.lastname: Pandey
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000367:Age Factors; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000235:genetics / Q000276:immunology; D060908:CTLA-4 Antigen; D020031:Epstein-Barr Virus Infections / Q000150:complications* / Q000208:ethnology / Q000276:immunology; D005006:Ethnicity / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D004854:Herpesvirus 4, Human / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000208:ethnology / Q000276:immunology / Q000821:virology*; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D013022:South Carolina / Q000453:epidemiology; D044465:White People
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human