J Biol Regul Homeost Agents. Mar-Apr 2021;35(2):417-422. doi: 10.23812/Theo_edit


Antibodies for COVID-19 – which, when and how long?


T.C. Theoharides 1,2,3, D. Lauritano 4, G.Ronconi 5, V. Calvisi 6 and P. Conti 7

1 Laboratory of Molecular Immunopharmacology and Drug Discovery, Department of Immunology, Tufts University School of Medicine, Boston, USA
2 School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
3 Department of Internal Medicine, Tufts University School of Medicine and Tufts Medical Center, Boston, MA,USA
4 Medicine and Surgery Department, Centre of Neuroscience of Milan, University of Milan-Bicocca, Italy
5 Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Rome, Italy
6 Department of Orthopaedics, School of Medicine, University of L’Aquila, L’Aquila, Italy
7 Postgraduate Medical School, University of Chieti, Chieti, Italy


Infection with SARS-CoV2  leads to COVID-19, the severity of which derives from the host’s immune response, especially the release of a storm of pro-inflammatory cytokines. This coronavirus infects by first binding to the ectoenzyme Angiotensin Converting Enzyme 2 (ACE2), a serine protease acting as the receptor, while another serine protease is necessary for priming the viral spike “S” protein required for entering the cells. Repurposing existing drugs for potential anti-coronavirus activity have failed. As a result, there were intense efforts to rapidly produce ways of providing prophylactic active immunization (vaccines) or abortive passive (convalescent plasma or monoclonal antibodies) neutralizing antibodies. The availability of vaccines for COVID-19 have been largely successful, but many questions still remain unanswered.  In spite of the original enthusiasm, clinical studies using convalescent serum or monoclonal antibodies have shown limited benefit. Moreover, the emergence of Long-COVID syndrome in most infected patients necessitates the development of treatment approaches that may prevent viral entry by blocking both serine proteases involved, as with a liposomal blend of the natural flavonoids luteolin and quercetin.


Key words: ACE2,  antibodies,  convalescent serum,  corona virus,  receptor,  S protein

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