o:25946 IgM and IgG immunoreactivity of SARS-CoV-2 recombinant M protein IgM i IgG imunoreaktivnost rekombinatnog SARS-CoV-2 M proteina en ABSTRACT Diagnostic evaluation of specific antibodies against the SARS CoV-2 virus is mainly based on spike (S) and nucleocapsid (N) proteins. Despite the critical functions in virus infection and contribution to the pattern of immunodominance in COVID-19, exploitation of the most abundant membrane (M) protein in the SARS-CoV-2 serology tests is minimal. This study investigated the recombinant M protein’s immunoreactivity with the sera from COVID-19 convalescents. In silico designed protein was created from the outer N-terminal part (19 aa) and internal C-terminal tail (101–222 aa) of the M protein (YP_009724393.1) and was recombinantly produced and purified. The designed M protein (16,498.74 Da, pI 8.79) revealed both IgM and IgG reactivity with serum samples from COVID-19 convalescents in Western blot. In ELISA, more than 93% (28/30) of COVID-19 sera were positive for IgM detection, and more than 96% (29/30) were positive for specific IgG detection to M protein. Based on the capacity to provoke an immune response and its strong antigenic properties, as shown here, and the fact that it is also involved in the virion entry into host cells, the M protein of the SARS-CoV-2 virus as a good antigen has the potential in diagnostic purposes and vaccine design. SARS-CoV-2 membrane protein, COVID-19, IgM reactivity, IgG reactivity, antigenicity, ELISA 1552099 10.3390/ijms22094951 2022-06-06T10:09:31.114Z 44 yes 46 Zorana Lopandić University of Belgrade, Faculty of Chemistry, Department of Biochemistry, Serbia Marija Gavrović-Jankulović University of Belgrade, Faculty of Chemistry, Department of Biochemistry, Serbia person Danica Ćujić University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia doktor medicinskih nauka-farmacija person Marija Gnjatović University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia doktor biotehničkih nauka person 0000-0001-8233-1636 Sofija Glamočlija University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia person 0000-0003-0497-5852 Aleksandra Todorović University of Belgrade, Institute for the Application of Nuclear Energy INEP, Serbia person 0000-0003-2225-8988 Isidora Protić-Rosić University of Belgrade, Faculty of Chemistry, Department of Biochemistry, Serbia person application/pdf 12176077 https://phaidrabg.bg.ac.rs/o:25946 no yes 16 70 92000001 11A19 11A1903 11A29 11A2904 International Journal of Molecular Sciences 22 9 MDPI 2021