Hello Vijay, on one hand there are viral proteins HBc and HBx bound to or associated with cccDNA, yet whether they are epigenetic modified is largely unknown. On the other hand, host histones (most investigated) as well as transcriptional enhancers and repressors (p300, etc.) modulate transcription from cccDNA, which was identified using chromatin immunoprecipitation assay (ChIP) in monomer- or minicircle-transfected cells. Recently the combination of ChIP and deep sequencing identified that these factors bind promoter/enhancer regions on cccDNA. To partially answer your question, cccDNA methylation, histone methylation and acetylation are major epigenetic modifications.