More importantly we were able to detect a variety of proteoforms including phosphorylated proteoforms in all serotypes and unacetylated and M203-VP3 proteoforms in AAV8 and AAV9, respectively. We also identified the presence of a VP3 variant at M211 in AAV6 and AAV8, most likely generated by leaky scanning of the initial start codon of VP3 at M203. Additionally, we were able to detect a variety of low abundant fragments originating from the truncation of either the N-or Cterminus. It is possible that the fragments generated from N-terminus truncation are a product of degradation caused by the baculovirus v-cath protease or Sf9 cellular response to baculovirus infection, while fragments generated from C-terminus truncation are the result of forced cleavage at the DP sequence through hydrolysis due to the acidic conditions the analysis was performed under.