Contribution of Fc-dependent cell-mediated activity of a vestigial esterase-targeting antibody against H5N6 virus infection

Abstract

The highly pathogenic avian influenza A (H5N6) virus has caused sporadic human infections with a high case fatality rate. Due to the continuous evolution of this virus subtype and its ability to transmit to humans, there is an urgent need to develop effective antiviral therapeutics. In this study, a murine monoclonal antibody 9F4 was shown to display broad binding affinity against H5Nx viruses. Furthermore, 9F4 can neutralize H5N6 pseudotyped particles and prevent entry into host cells. Additionally, ADCC/ADCP deficient L234A, L235A (LALA) and CDC deficient K322A mutants were generated and displayed comparable binding affinity and neutralizing activity as wild type 9F4 (9F4-WT). Notably, 9F4-WT, 9F4-LALA and 9F4-K322A exhibit in vivo protective efficacies against H5N6 infections in that they were able to reduce viral loads in mice. However, only 9F4-WT and 9F4-K322A but not 9F4-LALA were able to reduce viral pathogenesis in H5N6 challenged mice. Furthermore, depletion of phagocytic cells in mice lungs nullifies 9F4-WT's protection against H5N6 infections, suggesting a crucial role of the host's immune cells in 9F4 antiviral activity. Collectively, these findings reveal the importance of ADCC/ADCP function for 9F4-WT protection against HPAIV H5N6 and demonstrate the potential of 9F4 to confer protection against the reassortant H5-subtype HPAIVs.

Monoclonal antibodies for the S2 subunit of spike of SARS-CoV-1 cross-react with the newly-emerged SARS-CoV-2

“…The variable heavy (VH; GenBank accession number: DQ168569) and variable light (VL; GenBank accession number: DQ168570) genes of CR3022 were generated by gene synthesis (Bio Basic Asia Pacific) and cloned into pFUSEss-CHIg-hIgG1 and pFUSE2ss-CLIg-hK cloning vectors (InvivoGen, San Diego, CA, United States) respectively. Transfection of suspension FreeStyle 293 cells (Thermo Fisher Scientific) and purification of antibodies by fast protein liquid chromatography is as described in our previous study [23].…”

The development and kinetics of functional antibody-dependent cell-mediated cytotoxicity (ADCC) to SARS-CoV-2 spike protein

“…Effector immune cells, most commonly natural killer (NK) cells, bind to the antibodies via Fc receptors on their surface and then undergo degranulation releasing perforin and granzyme lysing infected cells. ADCC has been observed after infection with a number of viral pathogens ( Garcia et al, 2006 ; He et al, 2016 ; Singh et al, 2018 ), and it has been demonstrated to be an important component of protective immunity against HIV-1 ( Asokan et al, 2020 ; Haynes et al, 2012 ; Su et al, 2019 ), Influenza ( Gao et al, 2020b ; Zheng et al, 2020 ), Ebola ( Wagstaffe et al, 2019 ) and may have a role in other viral infection ( Chen, 2020 ). Since little is known about the role of ADCC in SARS-CoV-2 infections, we developed a functional SARS-CoV-2 spike (S) protein-based ADCC assay to assess the development and kinetics of antibodies after SARS-CoV-2 infection.…”

Comprehensive Molecular Epidemiology of Influenza Viruses in Brazil: Insights from a Nationwide Analysis

“…One (G225D) of the mutations is shared among the dominant subclades, and four others (E50K, F79V, I140K, and G186D) are typically encoded by viruses from the 2b subclade [55]. Notably, the G225D, I140K, and N186D are in the sialic acid binding site, and the E50K and F79V substitutions are situated in the F' and VE domains [20,[65][66][67]. Mutations within the receptor-binding domain can alter the interaction between the HA protein and alpha-2,3 or alpha-2,6 sialic acids across diverse host species [68].…”