3969
When the same single - amino - acid mutations were directly introduced into the parental PV / CBV4 - 2A genome , chimeric viruses with a large - plaque phenotype and a wild - type PV - like growth pattern were obtained upon transfection , an observation demonstrating that these point mutations alone had a drastic effect on the growth of the PV / CBV4 chimeric virus .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 None