what is ade

Antibody-dependent enhancement (ADE) is a phenomenon in which binding of a virus to suboptimal antibodies enhances its entry into host cells, followed by its replication. The suboptimal antibodies can result from natural infection or from vaccination. ADE may cause enhanced respiratory disease, but is not limited to respiratory disease. It has been observed in HIV, RSV virus, and Dengue virus and is monitored for in vaccine development. ADE may occur because of the non-neutralizing characteristic of an antibody, which binds viral epitopes other than those involved in host-cell attachment and entry. It may also happen when antibodies are present at sub-neutralizing concentrations or when the strength of antibody-antigen interaction is below a certain threshold. This phenomenon can lead to increased viral infectivity and virulence. ADE can occur during the development of a primary or secondary viral infection, as well as with a virus challenge after vaccination. It has been observed mainly with positive-strand RNA viruses, including flaviviruses such as dengue, yellow fever, and Zika; alpha- and betacoronaviruses; orthomyxoviruses such as influenza; retroviruses such as HIV; and orthopneumoviruses such as RSV. ADE is something researchers watch for very carefully and is extremely rare. In ADE, certain antibodies make it easier for viruses to get into cells. This is bad because it would mean a virus or a vaccine makes people more at risk for severe disease.