NTRK1 and viral infectious disease: Multiple stimuli induce expression of IEGs that include trophic factors downstream of receptor tyrosine kinases (RTKs, e.g., EGFR, TrkA, TrkB), calcium channels (e.g., NMDAR), neurotransmitters (glutamine, dopamine), and viral infection (Bahrami and Drabløs, 2016; Minatohara et al., 2016; Gallo et al., 2018).