PRF1 and COVID-19: Secondly, various cytotoxic molecules (e.g., PRF1, GZMA and GNLY, etc.)that were highly expressed in T and NK cells might also be associated with the immunopathology in COVID-19 acute necrotizing encephalopathy patients, because these effector molecules can damage multiple organs, including the CNS, by eliciting an inflammatory response and degrading the extracellular matrix.