Viral triggers of Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is a leading cause of acquired acute neuromuscular paralysis and is an immune-mediated disorder of the peripheral nervous system (PNS). Accumulating evidence indi-cates that GBS is often preceded by infectious events that trigger autoimmune responses through mechanisms such as molecular mimicry and autoantibody production. Campylobacter jejuni remains the most common bacterial agent, but viral pathogens also contribute to the development of GBS. This review summarizes the current evidence regarding viruses as triggers of GBS, including herpes-viruses, hepatotropic viruses (A, B, C, and E), human immunodeficiency virus, Zika virus, influenza virus, varicella-zoster virus, and the coronavirus SARS-CoV-2. Emphasis is placed on laboratory test results related to viral GBS, including antiganglioside antibodies, serological markers of recent in-fection, molecular diagnostic methods, and cerebrospinal fluid analysis. From the standpoint of la-boratory medicine, both the clinical diagnosis and the distinction of GBS subtypes can be supported by the identification of recent viral infections and the detection of immunological biomarkers. How-ever, cross-reactivity, extended antibody persistence, and inadequate assay standardization frequently make it difficult to interpret laboratory test results. In patients with probable viral GBS, this review shows the diagnostic significance and limitations of routine laboratory testing. It also highlights the significance of close coordination between laboratory professionals and clinicians.