A fully national COVID-19 booster vaccine is ready for human trials. The innovative substance, developed by the Center for Vaccine Technology of the Federal University of Minas Gerais (CTVacinas-UFMG) in partnership with Fundao Oswaldo Cruz (Fiocruz), targets a different viral protein than other immunizers targeting Sars-CoV-2. . In an article published in the journal Nature Communications, the authors of the study reported that the so-called SpiN-Tec elicited a strong immune system response to delta and micron variants in addition to the original strain.
“We have very positive expectations, several people have already applied for the tests, excited about the opportunity to get the Brazilian vaccine,” says Ricardo Gazzinelli, CTVacinas coordinator and researcher at Fiocruz. “One minute after Anvisa approves the tests, we will make an important announcement,” he says. The National Health Oversight Agency must authorize human trials, as does the National Commission on Research Ethics (Conep), which has already authorized the experiment. Gazzinelli says all documentation is already in place with the bodywork, and experimentation should begin later this year.
At the first stage of testing, 80 volunteers aged 20 to 59 will take part. Then another 400 people over 59 will enter. In all cases, participants will have to wait more than half a year after being vaccinated against COVID-19; no matter what previous immunizer was used. However, in clinical trials, volunteers will be initially vaccinated with Astrazenec.
Gazzinelli explains that from the very beginning of research with SpiN-Tec, the goal of scientists was to create a booster vaccine. “We were already expecting that when the human trial phase comes, a large part of the population will be vaccinated, which will be a problem,” he says. In addition to being idealized and made in Brazil, SpiN-Tec is a fusion of two coronavirus proteins to stimulate an immune response. In addition to the spike used by Sars-CoV-2, the vaccine consists of a nucleocapsid, a structure that houses the viral genetic material.
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Merge
The combination of proteins led to the formation of a molecule that in the body stimulates the production of T-lymphocytes, cells of the defense system specialized in recognizing Sars-CoV-2 and destroying it. A problem with modern vaccines is spike mutations, which make it difficult to detect the virus and therefore reduce the effectiveness of the substances. According to Gazzinelli, the nucleocapsid is much more stable and therefore less subject to variation. In the course of the study, SpiN-Tec showed the same efficacy against delta and micron variants as the original Wuhan strain.
By itself, the Brazilian vaccine does not cause the formation of antibodies. However, as a booster dose, the substance stimulates cellular immunity – the response of T cells and helpers – and humoral immunity, which produces specific immunoglobulins. Thus, SpiN-Tec finds itself on two fronts.
In an article published in Nature Communications, the authors report the results of studies in mice conducted in the laboratory of the Faculty of Medicine of Ribeiro Preto, USP (FMPR-USP) supported by the Fundao de Amparo Pesquisa do Estado de So. Paulo (FAPESP). Animals have been genetically engineered to express the ACE2 protein, which in humans is used by the Sars-CoV-2 spike to enter cells and thus start the replication cycle. Guinea pigs have also been modified to mimic severe covid.
Animals were divided into groups: one part received two doses of SpiN-Tec with an interval between them of 21 days. In the rest, the researchers administered a placebo. A month later, mice were subjected to an intranasal high load of Sars-CoV-2 both in the initial variant and in beta, delta, and micron variants.
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“In the placebo group, 100% of the animals infected with the Wuhan or delta strain died,” Giuliana Castro, a doctoral student led by Gazzinelli who led the preclinical trials, told Agencia FAPESP. “The mice exposed to the micron did not progress to death, but they did develop significant pathology in their lungs. In the immunized group, all animals survived the three strains and lung tissue was much better preserved. In addition, we saw a reduction in viral load that ranged from 50 to 100 times.”
In a hamster model that mimics mild COVID-19, the vaccine has also been successfully tested against baseline and delta variants. The immunized animals had a 10-fold lower viral load in addition to less lung damage compared to the placebo group. The substance was also tested on rabbits and on the blood of convalescents (people who recovered from Covid-19) with the same effectiveness.
According to Natlia Salazar, a researcher at CTVacinas, the technology used in SpiN-Tec – combining a recombinant protein with an adjuvant that enhances the immune response – is based on genetically modifying the E. coli bacterium, which received pieces of the Sars-CoV-2 genome, thus producing spine and nucleocapsid. She explains that the method can be used for other diseases. “Before the pandemic, we were already working with this technology for diseases such as leishmaniasis and chagas. The urgency caused by the emergence of covid-19 helped us develop this solution as quickly as possible,” he says. CTVacinas is also currently investigating a monkeypox immunizer.