CTLA4 and neoplasm: Here, using TCGA RNA-Seq data for six virus-associated tumors, we systematically study the associations between virus-positivity and the tumor microenvironment, as measured by expression of PD-L1, PD-L2, PD-1, CD80, CD86, CTLA-4, Tim-3, LAG3, and 4-1BB and the prevalence of infiltrating immune cells across multiple types of human cancers.