Elevated cerebrospinal fluid IgG index in herpes simplex encephalitis post-HSV-1 clearance: A preliminary study

Area of Science:

• Neuroimmunology
• Infectious Diseases
• Neurology

Background:

• Herpes simplex encephalitis (HSE) can cause severe neurological deficits.
• The precise mechanisms driving HSE pathogenesis are not fully understood.
• Postinfectious immune-inflammatory processes in the central nervous system (CNS) are increasingly implicated.

Purpose of the Study:

• To investigate the link between central nervous system (CNS) autoimmune responses and clinical presentation in HSE patients.
• To analyze cerebrospinal fluid (CSF) characteristics, specifically the IgG index, in relation to HSE.
• To clarify the role of immune responses in HSE development and progression.

Main Methods:

• Retrospective analysis of 176 patients with suspected aseptic meningitis/encephalitis.
• Polymerase chain reaction (PCR) screening of CSF for herpesviruses (HV).
• Monitoring of CSF findings and clinical presentations, including IgG index and anti-neural autoantibodies.

Main Results:

• Seven patients were positive for herpes simplex virus type 1 (HSV-1).
• A significant increase in CSF IgG index was observed in HSV-1 positive patients after PCR-negative conversion.
• No anti-neural autoantibodies were detected in HSV-1 positive patients approximately 3 weeks post-onset.

Conclusions:

• CSF IgG index elevation in HSE can occur after viral clearance, suggesting immunopathogenesis.
• These immune responses may be independent of direct antibody-mediated mechanisms.
• Findings contribute to understanding the complex interplay of immune responses in HSE.