45–50 In NTHI, there is a coordination between the production of the ToxA/VapA toxin/antitoxin system and tryptophan biosynthesis, suggesting that responses to stress through ToxA/VapA is multifactorial and metabolism mediated.51 Taken together with our prior studies,33 tryptophan biosynthesis appears to contribute to both biofilm formation and IBC development, indicators of persistence of NTHI during OM. Here, VAPA is linked to ocular melanoma.