Background Elevated Epstein-Barr virus (EBV) antibody titers are risk factors for MS, but the strength and consistency this association are not well characterized. Objectives To determine whether this association is confounded by vitamin D or modified by gender or race, and the usefulness of EBV nuclear antigen (EBNA) antibodies as a marker for MS. Methods We conducted a prospective study among US military personnel. Antibody titers against EBV antigens were measured in serum samples from 222 individuals who developed MS and 444 age, sex, and race/ethnicity matched controls. Conditional logistic regression was used to estimate relative risks. Results MS risk increased with increasing titers of anti-EBNA complex (p<10−9) and anti-EBNA-1 (p=5.8E-9) titers. MS risk was 36-fold higher among individuals with anti-EBNA complex IgG titers ≥320 than among those with titers <20 (95%CI:9.6-136), and 8-fold higher among those with anti-EBNA-1 ≥320 than among those with anti-EBNA-1 <20 (95%CI:2.6-23). These associations were consistent across gender and race/ethnicity groups and independent from 25-hydroxyvitamin D levels. Areas under the ROC curves were 0.67 for EBNA complex and 0.65 for EBNA-1. Conclusions Serum titers of pre-onset anti-EBNA antibodies are strong, robust markers of MS risk and could be useful in an MS risk score.

Objective: To examine the interplay between smoking, serum antibody titers to the Epstein-Barr virus nuclear antigens (anti-EBNA), and HLA-DR15 on multiple sclerosis (MS) risk.Methods: Individual and pooled analyses were conducted among 442 cases and 865 controls from 3 MS case-control studies-a nested case-control study in the Nurses' Health Study/Nurses' Health Study II, the Tasmanian MS Study, and a Swedish MS Study. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% CIs for the association between smoking, anti-EBNA titers, HLA-DR15, and MS risk. Study estimates were pooled using inverse variance weights to determine a combined effect and p value.Results: Among MS cases, anti-EBNA titers were significantly higher in ever smokers compared to never smokers. The increased risk of MS associated with high anti-EBNA Ab titers was stronger among ever smokers (OR ϭ 3.9, 95% CI ϭ 2.7-5.7) compared to never smokers (OR ϭ 1.8, 95% CI ϭ 1.4 -2.3; p for interaction ϭ 0.001). The increased risk of MS associated with a history of smoking was no longer evident after adjustment for anti-EBNA Ab titers. No modification or confounding by HLA-DR15 was observed. The increased risk of MS associated with ever smoking was only observed among those who had high anti-EBNA titers (OR ϭ 1.7, 95% CI ϭ 1.1-2.6).Conclusions: Smoking appears to enhance the association between high anti-EBNA titer and increased multiple sclerosis (MS) risk. The association between HLA-DR15 and MS risk is independent of smoking. Further work is necessary to elucidate possible biologic mechanisms to explain this finding. Neurology Multiple sclerosis (MS) is the most common nontraumatic disabling neurologic disease among young adults in the United States.1 The exact mechanism resulting in disease progression is unknown, though likely autoimmune in origin. Risk factors that have been consistently associated with increased MS risk include the HLA-DRB1*1501 haplotype in Caucasian populations, 2 high antibody levels against the Epstein-Barr virus (EBV), 3 and a smoking history. 4Whether these factors are independently associated with risk of MS or are related, possibly suggesting a common biologic mechanism, is unclear. We recently observed that the associations between HLA-DR15 positivity and EBV infection are independent MS risk factors. 5,6 However, the risk of MS associated with smoking independent of the other 2 factors and potential 3-way relationships have not been investigated.

Smoking is associated with an increased risk for early conversion to clinically definite multiple sclerosis after a clinically isolated syndrome, and our results suggest that smoking is an independent but modifiable risk factor for disease progression of multiple sclerosis. Therefore, it should be considered in the counseling of patients with a clinically isolated syndrome.

To assess whether variation in human endogenous retrovirus (HERV)-K18 env, an Epstein-Barr virus (EBV) associated superantigen, is a risk factor for multiple sclerosis (MS), we developed a SNP-based genotyping method to determine the allelic and genotypic distribution of the three alleles of HERV-K18 env. We conducted a nested case-control study amongst 207 MS cases and 403 matched controls drawn from two large ongoing cohorts, the Nurses Health Study and Nurses Health Study 2 (NHS/NHS2). Analyses were replicated in an independent series of 909 MS cases and 339 controls. Overall, in the NHS/NHS2 there was a significant association between HERV K18 env genotype and risk of MS (χ2 p-value=0.03). As compared with individuals homozygous for the K18.2 allele, risk of MS three fold higher among carriers of two K18.3 alleles (p=0.03). An increase in MS risk among carriers of the K18.3 allele was also observed in the replication study, but did not reach statistical significance. In pooled analyses, homozygous carriers of the K18.3 allele had a significantly increased risk of MS (RR comparing K18.3/K18.3 versus K18.2/K18.2 = 2.7; 95% CI: 1.1 to 6.4). These results suggest that variation in EBV-associated superantigen HERV-K18 env could influence the genetic susceptibility to MS.

Background The association between alcohol and caffeine intakes and risk of multiple sclerosis (MS) is unclear; no prospective studies have examined this relationship. Objective We examined intakes of alcohol and caffeine in relation to risk of multiple sclerosis. Design Intakes of alcohol and caffeine were examined in relation to risk of MS in two large cohorts of women, the Nurses’ Health Study (NHS; 92,275 women followed from 1980 to 2004) and Nurses’ Health Study II (NHS II; 95,051 women followed from 1991 to 2005). Their diet was assessed at baseline and every 4 years thereafter. During the follow-up, 282 cases of MS were confirmed with onset of symptoms after baseline. 24 cases were missing information on alcohol intake, leaving a total of 258 cases for the alcohol analyses. Results Neither total alcohol consumption, not consumption of beer, wine, or liquor was related to MS risk. The multivariable-adjusted pooled RRs comparing categories of alcohol intake to 0 grams/day were 1.07 (95% CI: 0.32–1.99) for 0.1–4.9 grams/day, 1.01 (0.32–1.99) for 5.0–14.9 grams/day, 1.21 (0.69–2.15) for 15.0–29.9 grams/day, and 0.80 (0.32–1.99) for 30+ grams/day; (p for trend 0.89). Caffeine intake was also not significantly associated with MS risk. The multivariable adjusted pooled RR comparing highest to lowest quintile of caffeine intake was 1.14; 95% CI: 0.79–1.66; p for trend 0.71. Consideration of caffeinated and decaffeinated coffee separately also yielded null results. Conclusion These results do not support an association between alcohol and caffeine intakes and MS risk.