What’s different about DELTA Variant Patients? This: The delta variant is almost like a whole new COVID virus, as it behaves very differently from the previous COVID strains. It has at least three mutations on its spike protein, and more specifically, on it receptor binding domain. That’s the part of the spike protein that binds to the ACE2 receptor on the cells in your body. The delta variant’s mutations help it bind more efficiently to the ACE2 receptor, and also allows the virus to enter the cell easier. Also, its mutations allow it to better evade the body’s immune system.