ERVW-1 and neoplasm: The murine leukemia virus envelope glycoprotein gp70 is a tumor-associated self-antigen expressed in BALB/c-derived tumor cell lines including AB1.41 We tracked 60 unique and public TCRβ CDR3 sequences derived from sorted H2-Ld restricted gp70423–431 (gp70-AH1) specific CD8+ TILs.42,43 In our bulk TCRβ sequencing data set, TCRβ clones with exact TRBV, TRBJ and CDR3 region matches with gp70-AH1 clones significantly increased over time in AB1 tumors and were dominant in some tumors, making up approximately 10–30% of the TCRβ repertoire (Figure 6(a)).