Lupus and the role of Epstein-Barr virus

[Guest guest]

Public release date: 7-Apr-2005

Contact: Amy Molnar

amolnar@...

Wiley & Sons, Inc.

Lupus and the role of Epstein-Barr virus

Study suggests a common viral infection may increase risk of lupus in

African Americans. Findings also show that genetic variation may affect

the immune response to Epstein-Barr virus in lupus patients.

Almost everyone has been infected with Epstein-Barr virus (EBV), a

member of the herpes family and one of the most common human viruses.

Symptoms of initial infection range from a typically mild childhood

illness with a fever and sore throat to mononucleosis in teenagers or

adults. After the initial infection, the virus settles into the cells

of the immune system called B cells, where it remains for life, mostly

dormant, with occasional bouts of reactivation and replication.

Maintaining EBV infection in a latent or quiet state primarily depends

on the power of another kind of immune cell, known as T cells. T cells

play a major role in keeping the immune system functioning properly.

Due to its interference with immune function and promotion of certain

antibodies, EBV has been implicated in systemic lupus erythematosus

(SLE), commonly referred to as lupus. Lupus is a chronic, potentially

debilitating autoimmune disease that more often affects women and is

also more common in African Americans. Although the specific cause of

lupus is not yet known, both genetic and environmental triggers are

likely to be involved.

To determine if there is an association between Epstein-Barr virus and

lupus, researchers in North and South Carolina compared the prevalence

of EBV antibodies in blood samples from lupus patients with those from

healthy controls. Published in the April 2005 issue of Arthritis &

Rheumatism (http://www.interscience.wiley.com/journal/arthritis), the

results of the National Institute of Environmental Health Sciences

(NIEHS) study show a strong association of EBV-IgA antibodies with

lupus in African Americans. In addition, their findings shed new light

on variation in a T-cell response gene that might influence immune

responsiveness to EBV among lupus patients.

Participants in the Carolina Lupus Study included 230 patients recently

diagnosed with lupus. Ranging widely in age, the subjects were 90

percent women and 60 percent African-American. Matched for age and sex,

controls were recruited from state driver's license registries. 30

percent of the enrolled controls were African-American, reflecting the

racial distribution of the geographic study area. Blood samples and

medical records were obtained for all participants.

Among both lupus patients and controls, African Americans had a higher

prevalence of EBV-IgG antibodies – the telltale sign of having a

history of EBV infection – than white subjects. However, another

antibody, EBV-IgA, seen with repeat or reactivated EBV infection, was

also more common in African Americans with lupus. EBV-IgA was found in

66 percent of African-American patients, and calculated at increasing

the odds for lupus by 5 to 6 fold. Among white lupus patients, the

EBV-IgA association was modest, yet increased significantly with age.

The association also appeared stronger in older African Americans than

younger patients.

Among lupus patients, both African-American and white, researchers also

observed a genetic variation in CTLA-4, a protein that works on T cells

in regulating immunity, and which significantly increased the risk of

lupus associated with EBV-IgA antibodies. This variation was previously

linked to risk of lupus in younger African Americans in the Carolina

Lupus Study.

" The racial difference in the association between EBV-IgA and SLE is

intriguing, especially since African Americans have a higher risk of

SLE, tend to develop the disease earlier, and often have a more severe

course of disease, " notes the study's leading author, G.

Parks, Ph.D., who performed the study as a post-doctoral fellow at the

NIEHS, one of the National Institutes of Health, in Research Triangle

Park, North Carolina. Dr. Parks is presently employed with the National

Institute for Occupational Safety and Health Sciences in town,

West Virginia. " One explanation could be that there are more

opportunities for reinfection among African Americans, given the higher

population prevalence of infection and likelihood of encountering and

becoming infected with new viral strains. Alternatively, other factors

independently related to the immune response to EBV and loss of latency

could vary by race, with the same difference being related to the

differential risk of SLE. "

Providing solid new serum-based evidence on the link between lupus and

Epstein-Barr virus, this study also calls attention to the need for

continued research into the role of race, age, and genetic variation in

autoimmune diseases.

The National Institute of Environmental Health Sciences is a federal

agency that conducts and funds basic research on the health effects of

exposure to environmental agents.

http://www.eurekalert.org/pub_releases/2005-04/jws-lat033105.php