Compared to cellular proteases, viral proteases are generally smaller in size and show low sequence similarity, even when sharing the same folding structure. Because of that, most viral proteases have unique substrate specificity, which has considerable implications for the design and development of potent antiviral molecules . The latest advances in structural biology methods like x-ray crystallography and NMR spectroscopy contributed significantly to increasing our knowledge of the viral proteases' structure and dynamics, which made them an attractive target for the development of novel antiviral drugs.