Per the article:
“a neutralizing antibody can subsequently transition to non-neutralizing antibody when encountering a different strain of the virus.”
“The exact mechanism of ADE in SARS is not known, but the leading theory is described as follows:
In certain viruses, the binding of a non-neutralizing antibody to the virus can direct the virus to enter and infect your immune cells. This occurs through a receptor called FcγRII. FcγRII is expressed on the outside of many tissues of our body, and in particular, in monocyte derived macrophages, which are a type of white blood cell.
In other words, the presence of the non-neutralizing antibody now directs the virus to infect cells of your immune system, and these viruses are then able to replicate in these cells and wreak havoc on your immune response. “