Can infections promote autoantibody formation without proving causation from coincident antibody findings?

Infections are credible triggers or amplifiers of autoreactivity, but causation in an individual patient requires substantially more than coincident laboratory findings.

Clinical and mechanistic evidence

• Molecular mimicry has the most direct support. Pathogen antigens can resemble self-proteins and induce cross-reactive antibodies. After primary EBV infection, EBNA-1–cross-reactive CRYAB antibodies were detected at 6 months and 1 year; blocking experiments supported genuine cross-reactivity. EBNA1–GlialCAM findings also include structural, affinity, and experimental evidence.
• Longitudinal SARS-CoV-2 data found newly detected autoantibodies after infection, more commonly after severe illness; 60% remained elevated at 12 months. These observations establish that infection-associated autoantibody emergence can occur, not that every detected antibody is pathogenic or that one mechanism explains all cases.
• Bystander activation and tissue injury are biologically credible contributors. Infection-induced cytokines and antigen-presenting-cell activation may expand autoreactive lymphocytes, while inflammatory tissue damage can expose or alter self-antigens and facilitate epitope spreading. Direct evidence tying either pathway to a particular post-infectious autoantibody remains less established than for mimicry.

Interpreting infectious and neural antibodies

• Simultaneous pathogen serology and neural-antibody positivity does not establish infection-caused autoimmunity. Pathogen IgG may indicate remote exposure or vaccination; IgM can persist, cross-react, or be falsely positive.
• Neural antibodies require phenotype-, specimen-, and assay-concordant interpretation. CSF can be particularly informative in relevant GFAP or NMDAR evaluations. Isolated serum reactivity, especially from broad panels or poorly reproducible assays, may be incidental.

Bottom line

• Infections can promote autoantibody formation—most convincingly through molecular mimicry—but co-occurring infectious and neural antibodies are hypothesis-generating, not proof of causality. Attribution requires credible acute infection, appropriate temporality, compatible neurologic syndrome and inflammatory findings, analytically reliable testing, and exclusion of alternatives.