SARS-CoV-2 Infection and Antibody-Dependent Enhancement

Abstract

There is still knowledge gap about the antibody response in COVID-19 patients. Factors affecting the kinetics/titers of the elicited neutralizing antibodies (NAbs), the mean persistence time of NAbs after infection, risk of reinfection, and enhanced respiratory disease via antibody-dependent enhancement (ADE) are the main issues needing to be clarified. Recently published studies have suggested an association between increased antibody titers and COVID-19 infection severity. Although there exist insufficient data, the titers of antibodies have been reported to be decreasing rapidly, suggesting a risk of reinfection. If reinfection occurs, another concern is whether it will be more severe due to the preexisting low level antibodies. To combat the continuing pandemic, antibody-based treatments, such as monoclonal antibodies (mAbs), convalescent plasma (CP) therapies, and vaccine studies, have been investigated. Although it may not be as troublesome as in the Dengue fever, clinicians should be alert about the possible risk of ADE. Non-neutralizing antibodies or sub-protective levels of NAbs may trigger immunopathogenic events via immune complex-mediated or Fc receptor-dependent endocytosis, resulting in enhanced viral infection. In this chapter, literature findings revealing the factors with an impact on eliciting NAbs, possible mechanisms and risks of ADE, and safety concerns for SARS-CoV-2 treatment interventions are outlined.