In order to study the many aspects of EBV in cell culture or in vivo models, it is necessary to create mutant virus that is designed to address our questions. We find that using fluorescent reporter proteins are useful for tracking infection efficacy and EBV reactivation efficiency. We are also capable of creating knock-outs for specific viral proteins in order to investigate the role of certain viral proteins in the EBV life cycle. Our lab has the ability to create a variety of mutant viruses through processes of homologous recombination in specifically engineered bacteria that result in a scarless manipulation of the viral genome. Scarless recombination through en passant mutagenesis generates mutant viral genomes in which the only modifications are our intended edits. Upon infection of mammalian cells with the bacteria harboring the modified viral genome and subsequent reactivation of the viral genome to produce virus, we can prepare and maintain these producer cell lines for future use.