Dödligt virus från Kina orsakar panik (SARS-CoV-2, COVID-19)

Antibody-dependent enhancement (ADE), sometimes less precisely called immune enhancement or disease enhancement, is a phenomenon in which binding of a virus to non-neutralizing antibodies enhances its entry into host cells, and sometimes also its replication. This phenomenon—which leads to both increased infectivity and virulence—has been observed with mosquito-borne flaviviruses such as Dengue virus, Yellow fever virus and Zika virus, with HIV, and with coronaviruses.

There are various hypotheses on how ADE happens and there is a likelihood that more than one mechanism exists. In one such pathway, some cells of the immune system lack the usual receptors on their surfaces that the virus uses to gain entry, but they have Fc receptors that bind to one end of antibodies. The virus binds to the antigen-binding site at the other end, and in this way gains entry to and infects the immune cell. Dengue virus can use this mechanism to infect human macrophages, if there was a preceding infection with a different strain of the virus, causing a normally mild viral infection to become life-threatening.

An ongoing question in the COVID-19 pandemic is whether—and if so, to what extent—COVID-19 receives ADE from prior infection with other coronaviruses.

ADE can hamper vaccine development, as a vaccine may cause the production of antibodies which, via ADE, worsen the disease the vaccine is designed to protect against. Vaccine candidates for Dengue virus and feline infectious peritonitis virus (a cat coronavirus) had to be stopped because they elicited ADE.