Isabelle Bezerra Cordeiro

The emergence of the P.1 variant of the SARS-CoV-2 virus is primarily responsible for the serious 2nd wave of infections that occurred in the city of Manaus, Amazonas, Brazil in early 2021. However, few studies seek to understand at the molecular level the reason for this, in addition to how neutralizing antibodies of different classes were affected. It was compared the influence of P.1/Gamma variant on antibody-antigen interaction in addition to the consequences in affinity for human ACE2 receptor. Regarding the simulations where we compared the P.1 variant, in fact the latter induced greater structural instability in the ACE2-RBD interaction, which may translate into greater affinity. In this way, based on the computational results, we propose that there were other factors besides molecular factors that made P.1 responsible for the greatest public health crisis in Brazil, since the affinity of the antigen for the ACE2 receptor was higher. And therefore, the vaccination campaign was certainly decisive in the fight against the Covid-19 pandemic, as the virus has been adapting to the human species over time.

The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) stands for being the most serious epidemic (so far) of the 21st century. However, only a few computational studies have investigated the molecular mechanisms underlying the neutralization of the spike protein by antibodies of different classes. Hence, bioinformatic methods were employed to unravel the factors contributing to the remarkable neutralization capacity exhibited by specific antibodies. Initially, crystallographic structures of IgA monomeric / dimeric, IgG, and IgM antibodies binding with the receptor-binding domain region of the SARS-CoV-2 spike protein were retrieved. Subsequently, rigid molecular docking and molecular dynamic simulations were performed over 100 ns with explicit water solvation. Lastly, an energy decomposition was conducted to estimate the binding affinity using the last frames from molecular dynamics. The results revealed a higher binding affinity for both monomeric and dimeric forms of IgA antibodies against the spike protein. Additionally, a greater number of hydrogen bonds were observed during their interaction with the spike protein, as well as greater structural instability along the time and especially a more thermodynamically favorable interaction affinity. In this way, the research contributes a small piece to the complex puzzle of understanding the humoral immune response induced by the SARS-CoV-2 virus.

Numerous studies have focused on inflammation-related markers to understand COVID-19. In this study, we performed a comparative analysis of spike (S) and nucleocapsid (N) protein-specific IgA, total IgG and IgG subclass response in COVID-19 patients and compared this to their disease outcome. We observed that the SARS-CoV-2 infection elicits a robust IgA and IgG response against the N-terminal (N1) and C-terminal (N3) region of the N protein, whereas we failed to detect IgA antibodies and observed a weak IgG response against the disordered linker region (N2) in COVID-19 patients. N and S protein-specific IgG1, IgG2 and IgG3 response was significantly elevated in hospitalized patients with severe disease compared to outpatients with non-severe disease. IgA and total IgG antibody reactivity gradually increased after the first week of symptoms. Magnitude of RBD-ACE2 blocking antibodies identified in a competitive assay and neutralizing antibodies detected by PRNT assay correlated with disease severity. Generally, the IgA and total IgG response between the discharged and deceased COVID-19 patients was similar. However, significant differences in the ratio of IgG subclass antibodies were observed between discharged and deceased patients, especially towards the disordered linker region of the N protein. Overall, SARS-CoV-2 infection is linked to an elevated blood antibody response in severe patients compared to non-severe patients. Monitoring of antigen-specific serological response could be an important tool to accompany disease progression and improve outcomes.

The COVID-19 pandemic has emphasized the importance and urgent need for rapid and accurate diagnostic tests for detecting and screening this infection. Our proposal was to develop a biosensor based on an ELISA immunoassay for monitoring antibodies against SARS-CoV-2 in human serum samples. The nucleocapsid protein (N protein) from SARS-CoV-2 was employed as a specific receptor for the detection of SARS-CoV-2 nucleocapsid immunoglobulin G. N protein was immobilized on the surface of a screen-printed carbon electrode (SPCE) modified with carboxylated graphene (CG). The percentage of IgG-SARS-CoV-2 nucleocapsid present was quantified using a secondary antibody labeled with horseradish peroxidase (HRP) (anti-IgG-HRP) catalyzed using 3,3′,5,5′-tetramethylbenzidine (TMB) mediator by chronoamperometry. A linear response was obtained in the range of 1:1000–1:200 v/v in phosphate buffer solution (PBS), and the detection limit calculated was 1:4947 v/v. The chronoamperometric method showed electrical signals directly proportional to antibody concentrations due to antigen-antibody (Ag-Ab) specific and stable binding reaction.

The COVID-19 pandemic has highlighted the importance and urgent need of rapid and accurate diagnostic tests for detection and screening of this infection. In our proposal, a biosensor based on the ELISA immunoassay was developed for monitoring antibodies against SARS-CoV-2 in human serum samples. The SARS-CoV-2 nucleocapsid protein (N-protein) was selected as a specific receptor for the detection of SARS-CoV-2 nucleocapsid immunoglobulin G. Thus, the N-protein was immobilized on surface of screen-printed carbon electrode (SPCE) modified with carboxylated graphene (CG). The IgG-SARS-CoV-2 nucleocapsid concentration was quantified using a secondary antibody labelled with horseradish peroxidase (HRP) (anti-IgG-HRP) catalyzed by 3,3’,5,5’-tetramethylbenzidine (TMB) mediator by chronoamperometry. A linear response was obtained in the range of 1:1000-1:200 v/v in phosphate buffer solution (PBS) and the limit of detection calculated was of 1:4947 v/v. The chronoamperometric method showed electrical signals directly proportional to antibody concentrations due to Ag-Ab specific and stable binding reaction.

Anais do Congresso Brasileiro Interdisciplinar em Ciência e Tecnologia (2764-0582) - Desenvolvimento De Um Jogo Didático Para Aprendizado Da Nomenclatura E Correto Manuseio Das Vidrarias De Laboratório

Anais do Congresso Brasileiro Interdisciplinar em Ciência e Tecnologia (2764-0582) - A Espécie Do Passado: Um Jogo Didático Para Abordar Os Conceitos Da Biofísica Da Respiração

Anais do Congresso Brasileiro Interdisciplinar em Ciência e Tecnologia (2764-0582) - Biocirculation: Um Jogo Estratégico Para O Ensino Da Biofísica Da Circulação

Anais do Congresso Brasileiro Interdisciplinar em Ciência e Tecnologia (2764-0582) - O Projeto De Extensão "Jogos Digitais Em Biofísica"