Summary The purpose of the Recombinant Virus Core C is to generate quality controlled recombinant herpesviruses for KSHV, EBV, and MHV68 (Projects 1, 2 and 3). The services of Core C will continue to aid the overall goal of the program project to comprehensively analyze the role of herpesvirus non-coding RNAs as well as studies on host cellular lncRNAs that are perturbed in response to viral infection. In addition to constructing recombinant viruses, Core C will perform genome-wide sequencing of viral mutants. Building upon years of experience in making a complete set of KSHV miRNA deletion mutants, our group has developed and implemented techniques for making bacmid-derived mutants in both KSHV and MHV68, and more recently also EBV. During the first funding period we designed, created and quality controlled more than 60 recombinant herpesviruses. Additional services and innovations are target enriched re-sequencing of latently infected producer cell lines for EBV and KSHV and applying innovative CRISPR technologies for mutagenesis.