PDCD1 and classic Hodgkin lymphoma: Another characteristic of P3HR1-infected CBH mice reminiscent of human CHL lymphomas is the increased expression of the CD4 transcript (suggestive of CD4 T cell infiltration) and PD1 transcript (suggestive of exhausted T cells) in the P3HR1-infected lymphomas versus B95.8 infected lymphomas on RNAseq (Fig 10).