CD274 and cyclic hematopoiesis: A similar trend was seen after treatment with anti-PD-L1 as PBMC from none of 4 animals with CH acquired after WHV infection in adulthood showed WHV-specific CTL response, while two of the four animals with CH after neonatal infection demonstrated activation of these cells in response to stimulation with WHV peptides, although one responded weakly (< 50% cells activated).