EPC (Evolved Packet Core) is one of the part of EPS. EPS is the combination of E-UTRAN and EPC. EPC consists of majorly MME, SGW and PGW nodes. Before the virtualization technology, all these nodes were known for tight coupling of hardware and software.
Virtualization mainly mean decoupling of hardware and software, scalability based on demand, come faster into the market etc. Virtualization does not change any feature or functionality of a node. For a node does not matter whether it is running in virtualized environment or in non-virtualized.
In virtualization environment, a virtual layer will be on top of hardware (processors, memory and network interface cards). On top of virtual layer, Virtual machine will be running. One component known as Orchestrator would be there to monitor the things. All the component can be run on one virtual machine or each different node of EPC run on different virtual machines. These cases are dependent on requirement.