biostudies-literatureDavis SKPaul Ramsay FoundationHoward Hughes Medical InstituteNational Health and Medical Research CouncilWellcome TrustAustralian Research Councile1424https://www.ebi.ac.uk/biostudies/studies/S-EPMC9588388biostudies-literatureUnknown11(10)<h4>Objectives</h4>Following infection with SARS-CoV-2, virus-specific antibodies are generated, which can both neutralise virions and clear infection via Fc effector functions. The importance of IgG antibodies for protection and control of SARS-CoV-2 has been extensively reported. By comparison, other antibody isotypes including IgA have been poorly characterised.<h4>Methods</h4>Here, we characterised plasma IgA from 41 early convalescent COVID-19 subjects for neutralisation and Fc effector functions.<h4>Results</h4>Convalescent plasma IgA from > 60% of the cohort had the capacity to inhibit the interaction between wild-type RBD and ACE2. Furthermore, a third of the cohort induced stronger IgA-mediated ACE2 inhibition than matched IgG when tested at equivalent concentrations. Plasma IgA aClinical & translational immunologyHeterologous SARS-CoV-2 IgA neutralising antibody responses in convalescent plasma.PMC9588388208693/Z/17/ZGodfrey DIPymm PRedmond SJKent SJAdair AHaycroft ERDavis SKWheatley AKChung AWSelva KJLopez ETham WHLee WSJuno JAGherardin NAfalseHeterologous SARS-CoV-2 IgA neutralising antibody responses in convalescent plasma.<h4>Objectives</h4>Following infection with SARS-CoV-2, virus-specific antibodies are generated, which can both neutralise virions and clear infection via Fc effector functions. The importance of IgG antibodies for protection and control of SARS-CoV-2 has been extensively reported. By comparison, other antibody isotypes including IgA have been poorly characterised.<h4>Methods</h4>Here, we characterised plasma IgA from 41 early convalescent COVID-19 subjects for neutralisation and Fc effector functions.<h4>Results</h4>Convalescent plasma IgA from > 60% of the cohort had the capacity to inhibit the interaction between wild-type RBD and ACE2. Furthermore, a third of the cohort induced stronger IgA-mediated ACE2 inhibition than matched IgG when tested at equivalent concentrations. Plasma IgA a2022-01-01T00:00:00Z20222026-04-12T19:28:02.853Z2025-04-05T10:06:46.456ZS-EPMC95883883629941010.1002/cti2.1424