A new immunizer, still in the early stages of study, but which should even protect against variants of the new coronavirus. The project, of which he is one of the main researchers, is supported by FAPESP and is coordinated by Jorge Elias Kalil Filho, professor at FM-USP and head of the Clinical Immunology and Allergy Laboratory at Hospital das Clínicas (HC-FM-USP) .
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A vaccine in the form of an easy-to-apply, low-cost nasal spray, long-lasting protection even against variants and capable of blocking the action of the new coronavirus even in the nose, where infections begin. This is the objective of a project being developed by a group of researchers from the University of São Paulo (USP), in partnership with the Federal University of São Paulo (Unifesp) and the Oswaldo Cruz Foundation (Fiocruz).
The new immunizing agent, still in the early stages of study, was presented last Monday (30) during the ILP-FAPESP Science and Innovation Cycle.
“One of the advantages of nasal immunization is that it generates local immunity in the nose, in the oropharynx [parte da garganta logo atrás da boca] and in the lungs. It is exactly the ideal ‘territory’ to prevent the consolidation of a SARS-CoV-2 infection. Injectable vaccines are very good for inducing systemic immunity and also in the lungs, but they are not especially good for generating a protective response in the nasal and oropharynx region”, explained Edécio Cunha Neto, professor at the Faculty of Medicine (FM-USP) and researcher at the Laboratory of Immunology at the Instituto do Coração (InCor).
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Neto now highlights the need for “a second-generation immunizing agent capable of circumventing problems that arose during the course of immunization [escape imune ou efeitos adversos, por exemplo] and serve as a reinforcement to injectables”.
According to the researcher, the goal is to create a vaccine that generates long-lasting neutralizing antibodies and also robustly stimulates cellular immunity – that mediated by T lymphocytes, which recognize the pathogen and destroy infected cells.
In addition, the new vaccine should protect against strains of concern. To do this, the researchers are developing an antigen that can contain the region of protein S (spike, present on the surface of the virus) that binds to human cells (RBD) of three or four variants at the same time.
The antigen will also contain pieces of proteins that stimulate the cellular response, longer than that mediated by neutralizing antibodies. Therefore, it should include the so-called cytotoxic CD8+ T lymphocytes, which kill infected cells, and the CD4+ T lymphocytes, which help in antibody production and cytotoxic responses.
The expectation is that clinical trials will be carried out in 2022.
To know which variants should be targeted by a vaccine, it is essential to know which strains are most present in the country. For this, some groups in Brazil carry out the so-called genomic surveillance. The researcher explains that the work consists of sequencing the genome of the variants in circulation to determine which ones are of most concern in epidemiological terms.
In partnership with the City of São Paulo, the Joint Brazil-UK Center for Arbovirus Discovery, Diagnosis, Genomics and Epidemiology (CADDE), supported by FAPESP, is monitoring the prevalence of the delta variant of SARS-CoV-2 in the municipality. .
“In the beginning, the proportion of this strain was 2%, but it has been systematically rising and spreading in various parts of the city of São Paulo. Today we are around 33%. Unfortunately, the delta will predominate in the coming weeks”, stresses Ester Sabino, a professor at FM-USP and a researcher at the Institute of Tropical Medicine (IMT-USP).