All identifications were found in all 5 replicate injections performed per condition, a quality score ≥ 40, and a relative abundance ≥ 0.05 except where otherwise noted. Surprisingly, a significant amount of unacetylated VP3 (VP3) was also detected during intact analysis of the AAV8 samples, with peptide mapping revealing only 60.87% and 73.64% of VP3 being acetylated in the empty and full capsid samples, respectively (Table ). Unacetylated VP3 was not detected during the analysis of either the AAV6 or AAV9 serotypes with peptide mapping indicating near 100% acetylation of VP3 in both the empty and full capsids. (AAV6: Table , AAV9: Table ). Another unexpected discovery, this time found in the AAV9 samples, was the detection of a low level of unacetylated VP3 that had not undergone N-term methionine cleavage (M203-VP3). Peptide mapping confirmed the presence of this proteoform with the identification of peptides beginning at M203