Project Summary/Abstract While KSHV can be detected in blood and occasionally in semen, it is frequently secreted in saliva which is believed to be the main route of spread. Nearly 25 years after the identification of KSHV, however, the initial steps in KSHV oral infection and the expressions of host and KSHV genes are still poorly understood. Our main question is: while KSHV establishes latency in most cells and KS lesions by default, why does it lead to spontaneous lytic replication in oral epithelial cells and oral lesions? Our hypothesis is: this difference is due to the differences of viral epigenetics and genomics. As the previous grant has been primarily focused on the epigenetic regulation of KSHV, the current study will characterize the high-order genomic organization of KSHV and investigate the transcriptomic and epigenomic regulations of KSHV at the single cell level using 3D organotypic oral tissue infection model that closely resembles in vivo oral transmission.