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We have recently shown that infection of Epstein-Barr virus ( EBV ) genome-positive B cells by human herpesvirus 6 ( HHV-6 ) results in the expression of the immediate-early EBV Zebra gene , followed by virus replication (L.Flamand, I.Stefanescu, D.V.Ablashi, and J.Menezes, J.Virol.67:6768-6777, 1993).
 Epstein-Barr virus ( EBV ) genome-positive B cells, B cells, immediate-early EBV Zebra gene
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:
 Epstein-Barr virus ( EBV ) genome-positive B cells, B cells, immediate-early EBV Zebra gene