Elevated antibody reactivity to measles virus NCORE protein among patients with multiple sclerosis and their healthy siblings with intrathecal oligoclonal immunoglobulin G production.

BACKGROUND: Patients with multiple sclerosis (MS) and their healthy siblings with the MS oligoclonal bands (OCB) trait, (a hyperimmune condition in form of two or more CSF enriched OCBs) harbor in cerebrospinal fluid (CSF) and serum elevated immunoglobulin G (IgG) titers against measles crude whole-cell antigen. The underlying mechanism resulting in the increased IgG antibody reactivity to measles remains unclear. The response may represent specific IgG reactivity to measles antigens or unspecific auto-antibodies targeting cellular components in the crude whole virus antigens commonly used in detection assays.

OBJECTIVE: To determine the specificity of the measles IgG antibody reactivity by using a purified single nucleoprotein as antigen, thereby minimizing the contribution from auto-antibodies.

STUDY DESIGN: The conserved N-terminal portion of the measles nucleocapsid protein (NCORE) was expressed as a specific antigen devoid of human or primate components. Serological analyses were performed on CSF and sera from MS patients, their clinically healthy siblings and healthy unrelated controls.

RESULTS: MS patients demonstrated higher IgG reactivity compared to healthy controls in both CSF (P<0.001) and serum (P<0.001), and compared to siblings in CSF (P<0.001) and serum (P=0.2). Siblings with MS OCB trait showed higher IgG reactivity than healthy controls in CSF (P=0.002) and serum (P=0.01). Comparison between siblings with MS OCB trait and siblings without MS OCB trait showed (P=0.04) for CSF and (P=0.08) for serum.

CONCLUSION: These findings suggest a measles-specific component in the antibody reactivity demonstrated by MS patients and their siblings with the MS OCB trait.