GSR and viral infectious disease: Therefore, to better understand different responses to virus infection, the enzymatic activity of GST (EC 2.5.1.18) was evaluated, which is considered the marker for resistant/or even hypersensitive reaction to viral pathogens [16] and GR (EC 1.8.1.7) enzymatic activity, which is one of the most important enzymes in restoring GSH using GSSG during oxidative protection.