3888
This is consistent with a model proposing that SSV was generated by recombination between proviral DNA of a simian sarcoma associated virus and proto - sis and that introns were spliced out subsequently from a fused viral - sis messenger RNA .
 proto - sis, viral - sis messenger RNA
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 proto - sis, viral - sis messenger RNA