Neutralizing antibody (nAb)

Neutralizing antibodies (nAbs) are a specialized subset of immunoglobulins produced by the adaptive immune system that are capable of binding to a pathogen and directly inhibiting its infectivity. In the context of vaccination, the primary goal is to induce these antibodies to recognize specific surface proteins of a virus or bacterium, such as the receptor-binding domain of a viral spike protein, thereby preventing the pathogen from entering host cells (Nature Reviews Immunology, 2021). Unlike binding antibodies that may only flag a pathogen for destruction, nAbs provide a direct barrier to infection by blocking the physical interaction between the pathogen and the host cell receptor (NIH, 2023). The measurement of vaccine-induced nAbs, typically expressed as a neutralization titer, serves as a critical biomarker and correlate of protection in clinical trials for vaccines against diseases like COVID-19, influenza, and RSV (FDA, 2022). However, the long-term efficacy of these antibodies can be challenged by the emergence of viral variants that possess mutations in the targeted epitopes, leading to reduced binding affinity and potential immune evasion (The Lancet, 2022). Additionally, while generally protective, the presence of sub-neutralizing levels of antibodies can theoretically lead to antibody-dependent enhancement (ADE), a phenomenon where the antibody facilitates rather than prevents viral entry into certain cell types (Journal of Virology, 2020).

Other names

nAbsVirus-neutralizing antibodiesProtective antibodiesVaccine-induced antibodies

Neutralization of pathogens via steric hindrance or inhibition of receptor binding.