Epstein-Barr Virus (EBV) is a lymphotropic herpes virus and the causative agent of infectious mononucleosis (IM). The course of EBV infection is determined by the virus load and an individuals' immune system state, which in turn is determined by the person's gene composition, other infection history and several environmental factors, which all may influence the immune capacity of a person to various degrees. Many diseases are known to be associated with EBV infection, among those diseases are systemic autoimmune diseases. With regard to EBV, prior infection with the virus seems to be of crucial importance for the development of systemic lupus erythematosus (SLE). Autoantibodies against complement C1q (anti-C1q) can be induced in vivo by the Epstein-Barr virus-derived antigenic site 'EBNA348' (also being part of the C-terminal EBNA-1).

This study is to analyze whether the primary infection with EBV (leading to IM and antibodies targeting EBV-derived antigens including antibodies against EBNA-1) leads to an at least transient occurrence of antibodies against the virus that have the potential to cross-react with autoantigens as described in patients with systemic autoimmune diseases (e.g. complement C1q, dsDNA, Ro, Sm, MOG, NF186 and others). The advantage of an analysis of patients with primary infection is that the de novo synthesis of antibodies against the virus will allow to determine the time-dependent evolution of the antibody repertoire against the virus as well as against a number of autoantigens.