SARS-CoV-2 recombinant proteins stimulate distinct cellular and humoral immune response profiles in samples from COVID-19 convalescent patients

OBJECTIVES: In this preliminary study we investigated cellular and humoral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens in blood samples from 14 recovered coronavirus disease 2019 (COVID-19) patients and compared them to those in samples from 12 uninfected/unvaccinated volunteers. METHODS: Cellular immunity was assessed by intracellular detection of IFN-γ in CD3+ T lymphocytes after stimulation with SARS-CoV-2 spike (S1), nucleocapsid (NC), or receptor-binding domain (RBD) recombinant proteins or overlapping peptide pools covering the sequence of SARS-CoV-2 spike, membrane and nucleocapsid regions. The humoral response was examined by ELISAs and/or chemiluminescence assays for the presence of serum IgG antibodies directed to SARS-CoV-2 proteins. RESULTS: We observed differences between humoral and cellular immune profiles in response to stimulation with the same proteins. Assays of IgG antibodies directed to SARS-CoV-2 NC, RBD and S1/S2 recombinant proteins were able to differentiate convalescent from uninfected/unvaccinated groups. Cellular immune responses to SARS-CoV-2 protein stimuli did not exhibit a specific response, as T cells from both individuals with no history of contact with SARS-CoV-2 and from recovered donors were able to produce IFN-γ. CONCLUSIONS: Determination of the cellular immune response to stimulation with a pool of SARS-CoV-2 peptides but not with SARS-CoV-2 proteins is able to distinguish convalescent individuals from unexposed individuals. Regarding the humoral immune response, the screening for serum IgG antibodies directed to SARS-CoV-2 proteins has been shown to be specific for the response of recovered individuals

Enhanced immunogenicity and protective efficacy in mice following a Zika DNA vaccine designed by modulation of membrane-anchoring regions and its association to adjuvants

Zika virus (ZIKV) is a re-emerging pathogen with high morbidity associated to congenital infection. Despite the scientific advances since the last outbreak in the Americas, there are no approved specific treatment or vaccines. As the development of an effective prophylactic approach remains unaddressed, DNA vaccines surge as a powerful and attractive candidate due to the efficacy of sequence optimization in achieving strong immune response. In this study, we developed four DNA vaccine constructs encoding the ZIKV prM/M (pre-membrane/membrane) and E (envelope) proteins in conjunction with molecular adjuvants. The DNA vaccine candidate (called ZK_ΔSTP), where the entire membrane-anchoring regions were completely removed, was far more immunogenic compared to their counterparts. Furthermore, inclusion of the tPA-SP leader sequence led to high expression and secretion of the target vaccine antigens, therefore contributing to adequate B cell stimulation. The ZK_ΔSTP vaccine induced high cellular and humoral response in C57BL/6 adult mice, which included high neutralizing antibody titers and the generation of germinal center B cells. Administration of ZK-ΔSTP incorporating aluminum hydroxide (Alum) adjuvant led to sustained neutralizing response. In consistency with the high and long-term protective response, ZK_ΔSTP+Alum protected adult mice upon viral challenge. Collectively, the ZK_ΔSTP+Alum vaccine formulation advances the understanding of the requirements for a successful and protective vaccine against flaviviruses and is worthy of further translational studies

De novo design of immunoreactive conformationspecific HIV-1 epitopes based on Top7 scaffold

Submitted by Luciane Willcox ([email protected]) on 2016-09-16T17:09:31Z No. of bitstreams: 1 De novo design.pdf: 980251 bytes, checksum: cd50fe658dcec7c21d19b8fd628a792e (MD5)Approved for entry into archive by Luciane Willcox ([email protected]) on 2016-09-16T17:40:03Z (GMT) No. of bitstreams: 1 De novo design.pdf: 980251 bytes, checksum: cd50fe658dcec7c21d19b8fd628a792e (MD5)Made available in DSpace on 2016-09-16T17:40:03Z (GMT). No. of bitstreams: 1 De novo design.pdf: 980251 bytes, checksum: cd50fe658dcec7c21d19b8fd628a792e (MD5) Previous issue date: 2013-05-14FACEPE, NanoBiotec-BR/CAPES, CNPq, INCT-INAMI, nBioNet, Oswaldo Cruz Foundation.Federal University of Pernambuco. Department of Fundamental Chemistry. Recife, PE, Brazil.University of Pittsburg. Department of Infectious Diseases and Microbiology. Pittsburgh, USA.Oswaldo Cruz Foundation. Carlos Chagas Institute. Curitiba, PR, Brazil.Oswaldo Cruz Foundation. Aggeu Magalhães Research Center. Recife, PE, Brazil.Epitope exposure strategies often fail due to high conformational instability, resulting in loss of native conformation and fast degradation. Protein scaffolding, where a structural element of an antigen protein is transplanted into a scaffold acceptor protein, has been employed as an alternative solution. However, while this approach aims to preserve the epitope structure, it frequently results in unstable chimeric scaffolds. To overcome this issue, we employed a novel computational approach to rationally engineer conformational antigens into a highly stable scaffold protein. This strategy is showcased to display conformational HIV-1 gp41-based epitopes in their native structure. From HIV-1 antigen sequence databases, we have identified short sequences with the most probable antibody-recognizable regions. These sequences were inserted into or replaced regions of the original Top7 protein with analogous secondary structure assignment. Molecular dynamics simulations were used to characterize the protein stability and structural dynamic of the chimeric proteins, leading to a selection of promising candidates whose immunogenic epitopes are suitably exposed for antibody recognition. These computer-designed recombinant proteins were produced in bacteria using codon optimized DNA sequences and their diagnostic performance was assessed by liquid microarray against a human cohort of 47 sera samples. Our results show that the Top7 protein is a suitable scaffold to provide the required structural stability to predetermined target shapes and sequences, allowing the potential use of the chimeric proteins as antigens for specific antibody recognition and/or stimulation of immune response

LAMP-1 Chimeric to HIV-1 p55Gag in the Immunization of Neonate Mice Induces an Early Germinal Center Formation and AID Expression

Neonates have a limited adaptive response of plasma cells, germinal center (GC) B cells, and T follicular helper cells (TFH). As neonatal vaccination can be an important tool for AIDS prevention, these limitations need to be overcome. Chimeric DNA vaccine encoding p55Gag HIV-1 protein conjugated with lysosomal-associated membrane protein 1 (LAMP-1) has been described as immunogenic in the neonate period. Herein, we investigated the immunologic mechanisms involved in neonatal immunization with a LAMP-1/p55Gag (LAMP/Gag) DNA vaccine in a C57BL/6 mouse background. Neonatal LAMP/Gag vaccination induced strong Gag-specific T-cell response until adulthood and elevated levels of anti-Gag IgG antibodies. We also demonstrated for the first time that the immunogenicity of the neonatal period with LAMP/Gag is due to the induction of high-affinity anti-p24 IgG antibodies and long-term plasma cells. Together with that, there is the generation of early TFH cells and the formation of GC sites with the upregulation of activation-induced cytidine deaminase (AID) enzyme mRNA and protein expression in draining lymph nodes after neonatal LAMP/Gag vaccination. These findings underscore that the LAMP-1 strategy in the chimeric vaccine could be useful to enhance antibody production even in the face of neonatal immaturity, and they contribute to the development of new vaccine approaches for other emerging pathogens at an early stage of life

DataSheet_1_Enhanced immunogenicity and protective efficacy in mice following a Zika DNA vaccine designed by modulation of membrane-anchoring regions and its association to adjuvants.docx

Zika virus (ZIKV) is a re-emerging pathogen with high morbidity associated to congenital infection. Despite the scientific advances since the last outbreak in the Americas, there are no approved specific treatment or vaccines. As the development of an effective prophylactic approach remains unaddressed, DNA vaccines surge as a powerful and attractive candidate due to the efficacy of sequence optimization in achieving strong immune response. In this study, we developed four DNA vaccine constructs encoding the ZIKV prM/M (pre-membrane/membrane) and E (envelope) proteins in conjunction with molecular adjuvants. The DNA vaccine candidate (called ZK_ΔSTP), where the entire membrane-anchoring regions were completely removed, was far more immunogenic compared to their counterparts. Furthermore, inclusion of the tPA-SP leader sequence led to high expression and secretion of the target vaccine antigens, therefore contributing to adequate B cell stimulation. The ZK_ΔSTP vaccine induced high cellular and humoral response in C57BL/6 adult mice, which included high neutralizing antibody titers and the generation of germinal center B cells. Administration of ZK-ΔSTP incorporating aluminum hydroxide (Alum) adjuvant led to sustained neutralizing response. In consistency with the high and long-term protective response, ZK_ΔSTP+Alum protected adult mice upon viral challenge. Collectively, the ZK_ΔSTP+Alum vaccine formulation advances the understanding of the requirements for a successful and protective vaccine against flaviviruses and is worthy of further translational studies.</p