Protective roles and protective mechanisms of neutralizing antibodies against SARS-CoV-2 infection and their potential clinical implications

Abstract

Neutralizing antibodies (NAbs) are central players in the humoral immunity that defends the body from SARS-CoV-2 infection by blocking viral entry into host cells and neutralizing their biological effects. Even though NAbs primarily work by neutralizing viral antigens, on some occasions, they may also combat the SARS-CoV-2 virus escaping neutralization by employing several effector mechanisms in collaboration with immune cells like natural killer (NK) cells and phagocytes. Besides their prophylactic and therapeutic roles, antibodies can be used for COVID-19 diagnosis, severity evaluation, and prognosis assessment in clinical practice. Furthermore, the measurement of NAbs could have key implications in determining individual or herd immunity against SARS-CoV-2, vaccine effectiveness, and duration of the humoral protective response, as well as aiding in the selection of suitable individuals who can donate convalescent plasma to treat infected people. Despite all these clinical applications of NAbs, using them in clinical settings can present some challenges. This review discusses the protective functions, possible protective mechanisms against SARS-CoV-2, and potential clinical applications of NAbs in COVID-19. This article also highlights the possible challenges and solutions associated with COVID-19 antibody-based prophylaxis, therapy, and vaccination.

Dynamics of serum cross‐neutralization capacity against SARS‐CoV‐2 Delta variant in convalescent COVID‐19 patients

“…No significant difference between visits for the CNI was found in the conducted study as reported before 6 . The genetic distance between the infection and Delta variant could account for the absence of an increase in cross‐neutralization as observed for Alpha/Beta variants 12,13 . Most likely the affinity maturation of certain wild‐type specific neutralizing epitopes B cells may account for this increase 13 .…”

“…6 The genetic distance between the infection and Delta variant could account for the absence of an increase in cross-neutralization as observed for Alpha/Beta variants. 12,13 Most likely the affinity maturation of certain wild-type specific neutralizing epitopes B cells may account for this increase. 13 The report highlights for the first time that the dynamics of S1/S2 IgG may anticipate the dynamics of cross-neutralization capacity against Delta at 3 months PSO, but not at late time points.…”

Production and Immunogenicity Assessment of LTp50: An Escherichia coli-Made Chimeric Antigen Targeting S1- and S2-Epitopes from the SARS-CoV-2/BA.5 Spike Protein

“…Alternatively, post-binding inhibition effector mechanisms achieve the elimination of infected cells by the antibody-mediated effector mechanism, involving antibody-dependent cell cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and antibody-mediated complement-dependent cytotoxicity (CDC). These mechanisms imply the binding of the Fc area to specific Fcγ receptors (FcγR) present on the membrane of natural killer (NK) cells, macrophages, and neutrophils [ 52 ]. Antibody-enhanced disease (AED) refers to an immunopathological condition provoked by the presence of pre-existing antibodies against a pathogen that does not neutralize the virus [ 53 ].…”

Hybrid Immunity Improves the Immune Response after the Fourth COVID-19 Vaccine Dose in Individuals with Medical Conditions Predisposing to Severe COVID-19

“…Our study showed that after the fourth dose, the proportion of participants with a normal antibody response and those with NAb against the Omicron BA.1 variant was significantly lower in CKD and RD groups compared to the healthy controls. Numerous studies have consistently shown that the presence of neutralizing antibodies is a strong indicator of immune protection against SARS-CoV-2 infection [ 33 ]. Consequently, an impaired neutralizing antibody response suggests limited protection.…”