23851
Both compounds 1 and 2 were found to promote early infection events in HIV , likely by inhibiting the enzyme indolamine 2 , 3 - dioxygenase ( IDO ) and preventing tryptophan depletion .
 Chemical: indolamine; Chemical: tryptophan
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: indolamine; Chemical: tryptophan