12040
A few viruses, like the Herpesviruses or the papillomaviruses , however, have developed a sophisticated strategy for persisting lifelong, usually asymptomatically in the host, hiding from the immune system and producing infectious progeny at the same time.
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 None