CSF herpes virus and autoantibody profiles in the evaluation of encephalitis

Abstract

Objective: To report the frequency of coexisting herpes viruses (herpes simplex virus 1 [HSV-1] or HSV-2, varicella zoster virus, Epstein-Barr virus [EBV], cytomegalovirus, or human herpes virus 6 [HHV-6]) and autoantibodies in patients with encephalitis (herpes or autoimmune) in clinical laboratory service.

Methods: Three groups were evaluated for herpes viruses and antibodies: group 1-patients whose CSF was positive for a herpes virus by real-time PCR over a period of 6 months; group 2-patients whose CSF was positive for an autoimmune encephalitis-associated antibody over 5 years (e.g., NMDA receptor [NMDA-R] antibody), and the same number of controls without autoimmune/infectious disease; and group 3-incidental autoimmune parainfectious encephalitis cases encountered over 1 year.

Results: In group 1, antibodies were detected in 27 of 100 herpes PCR-positive CSF specimens (CSFs), either unclassified neural or nonneural in all but one patient with NMDA-R antibody detected after EBV infection. Antibodies were also detected in 3 of 7 CSFs submitted for repeat PCR testing (unclassified, 2; AMPA receptor, 1). In group 2, herpes viruses were detected in 1 of 77 controls (HHV-6) and 4 of 77 patients with autoimmune encephalitis (EBV, 2; HHV-6, 2); autoantibodies targeted NMDA-R in 3/4 and GABAB-R in 1/4. In group 3, NMDA-R antibody was detected in 7 patients post-HSV-1 encephalitis. Of the remaining 3 patients, 2 had unclassified neural antibodies detected, and one had GABAB-R autoimmunity. Concomitant neoplasms were discovered in 2 patients each from groups 2 and 3.

Conclusions: Autoantibodies and herpes virus DNA frequently coexist in encephalitic CSF. Some patients develop parainfectious autoimmunity following viral CNS infection (usually HSV-1 encephalitis). The significance of detecting herpes nucleic acids in others remains unclear.

Figure.. Groups 1–3, patients tested, and test results (viral PCR and antibodies)

Ab = antibody; AMPA-R = amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor; ANA = antinuclear antibody; CBA = cell-based assay; CSFs = CSF specimens; EBV = Epstein-Barr virus; GABA_B-R = γ-aminobutyric acid type B receptor; GPC = gastric parietal cell; HHV-6 = human herpes virus 6; HSV = herpes simplex virus; IFA = immunofluorescence assay; IgG = immunoglobulin G; NMDA-R = NMDA receptor; PCR = polymerase chain reaction; SMA = smooth muscle antibody; UNA = uncharacterized neural antibody.