7857
Indeed the predicted folding of the 5 ' and 3 ' - untranslated regions revealed patterns of stem and loop structures conserved for all tick - borne flaviviruses suggesting a purifying selection for preservation of essential RNA secondary structures which could be involved in translational control and replication .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 None