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Keywords:

  • autoimmunity;
  • molecular mimicry;
  • myasthenia gravis;
  • poliomyelitis;
  • neuromuscular junction;
  • West Nile virus

ABSTRACT

Introduction: Viruses are commonly cited as triggers for autoimmune disease. It is unclear if West Nile virus (WNV) initiates autoimmunity. Methods: We describe 6 cases of myasthenia gravis (MG) that developed several months after WNV infection. All patients had serologically confirmed WNV neuroinvasive disease. None had evidence of MG before WNV. Results: All patients had stable neurological deficits when they developed new symptoms of MG 3 to 7 months after WNV infection. However, residual deficits from WNV confounded or delayed MG diagnosis. All patients had elevated acetylcholine receptor (AChR) antibodies, and 1 had thymoma. Treatment varied, but 4 patients required acetylcholinesterase inhibitors, multiple immunosuppressive drugs, and intravenous immune globulin or plasmapheresis for recurrent MG crises. Conclusions: The pathogenic mechanism of MG following WNV remains uncertain. We hypothesize that WNV-triggered autoimmunity breaks immunological self-tolerance to initiate MG, possibly through molecular mimicry between virus antigens and AChR subunits or other autoimmune mechanisms. Muscle Nerve 49: 26–29, 2014