Evaluation of an RBD-nucleocapsid fusion protein as a booster candidate for COVID-19 vaccine.

Despite successful vaccines and updates, constant mutations of SARS-CoV-2 makes necessary the search for new vaccines. We generated a chimeric protein that comprises the receptor-binding domain from spike and the nucleocapsid antigens (SpiN) from SARS-CoV-2. Once SpiN elicits a protective immune response in rodents, here we show that convalescent and previously vaccinated individuals respond to SpiN.

ASP-2/Trans-sialidase chimeric protein induces robust protective immunity in experimental models of Chagas' disease.

Immunization with the Amastigote Surface Protein-2 (ASP-2) and Trans-sialidase (TS) antigens either in the form of recombinant protein, encoded in plasmids or human adenovirus 5 (hAd5) confers robust protection against various lineages of Trypanosoma cruzi. Herein we generated a chimeric protein containing the most immunogenic regions for T and B cells from TS and ASP-2 (TRASP) and evaluated its immunogenicity in comparison with our standard protocol of heterologous prime-boost using plasmids and hAd5. Mice immunized with TRASP protein associated to Poly-ICLC (Hiltonol) were highly resistant to challenge with T.

Differential requirement of neutralizing antibodies and T cells on protective immunity to SARS-CoV-2 variants of concern.

The current COVID-19 vaccines protect against severe disease, but are not effective in controlling replication of the Variants of Concern (VOCs). Here, we used the existing pre-clinical models of severe and moderate COVID-19 to evaluate the efficacy of a Spike-based DNA vaccine (pCTV-WS) for protection against different VOCs. Immunization of transgenic (K18-hACE2) mice and hamsters induced significant levels of neutralizing antibodies (nAbs) to Wuhan and Delta isolates, but not to the Gamma and Omicron variants.

Promotion of neutralizing antibody-independent immunity to wild-type and SARS-CoV-2 variants of concern using an RBD-Nucleocapsid fusion protein.

Both T cells and B cells have been shown to be generated after infection with SARS-CoV-2 yet protocols or experimental models to study one or the other are less common. Here, we generate a chimeric protein (SpiN) that comprises the receptor binding domain (RBD) from Spike (S) and the nucleocapsid (N) antigens from SARS-CoV-2. Memory CD4 and CD8 T cells specific for SpiN could be detected in the blood of both individuals vaccinated with Coronavac SARS-CoV-2 vaccine and COVID-19 convalescent donors.

Trypanosoma cruzi: role of δ-amastin on extracellular amastigote cell invasion and differentiation.

Trypanosoma cruzi is a protozoan parasite that comprises different phylogenetic groups and is the causative agent of Chagas' disease. Different T. cruzi strains present differences in infectivity in in vitro and in vivo experimental models, which are likely related to the expression of different virulence factors.