Molecular model of CcBV cystatin 1 obtained from the average structure. (A) The superimposed molecular dynamics (MD) average structure of CcBV cystatin 1 orange (1–5 ns), cyan (5–7 ns) and purple (8–10 ns) of 10 ns MD simulation trajectory. (B) Positively selected residues (probability 95%) are represented as a red colour capped stick model on the secondary structure (green) of the final model of CcBV cystatin 1 average structure (1–10 ns). Glycine in N-terminal and Valine and Alanine in the L1 are important for C1 protease binding. CcBV mature cystatin 1 amino acid numbering is used.