A 14-year-old boy develops insidious cognitive decline, behavioral change and recurrent myoclonic jerks. He had uncomplicated measles at age 2 years. EEG shows periodic complexes and CSF shows elevated gamma globulin with normal cell count. The pathogenesis of this complication involves:

• A Reactivation of latent virus from dorsal root ganglia
• B Autoimmune demyelination triggered by molecular mimicry
• C Immune complex deposition in cerebral vasculature
• D Persistent defective measles virus lacking M protein in neurons ✓

Explanation

Subacute sclerosing panencephalitis appears 5 to 10 years after measles and results from persistent CNS infection with defective measles virus that spreads cell to cell despite abundant neutralizing antibody. Mutations accumulate especially in the matrix (M) protein gene, preventing virion assembly and release, so free virus is absent while intracellular spread continues. Diagnosis rests on very high measles antibody titers in CSF. Reactivation from ganglia applies to herpesviruses, not paramyxoviruses.

Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 12th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.