(crédito: CTVacinas/UFMG/Divulgação)

Covid-19: UFMG and Fiocruz vaccine is ready for human trials

posted on 08/31/2022 06:09


(credit: CTVacinas/UFMG/Disclosure)

One hundred percent national, a booster vaccine for covid-19 is ready to be tested in humans. Conceived by the Center for Vaccine Technology at the Federal University of Minas Gerais (CTVacinas-UFMG) in partnership with the Oswaldo Cruz Foundation (Fiocruz), the substance is innovative in targeting a virus protein different from that targeted by other immunizing agents that fight the disease. SARS-CoV-2. In a paper published in the journal Nature Communications, the study authors reported that the so-called SpiN-Tec induces a robust immune system response against the delta and omicron variants in addition to the original strain.

“We have very positive expectations, several people have already applied for the tests, excited to be a Brazilian vaccine”, says Ricardo Gazzinelli, coordinator of CTVacinas and researcher at Fiocruz. “The minute after Anvisa approves the tests, we’re going to make a big announcement,” he says. The National Health Surveillance Agency needs to give approval for trials carried out with humans, as does the National Research Ethics Commission (Conep), which has already authorized the experiment. Gazzinelli says that the documentation is already with the organ, and the experiments should start later this year.

In the first phase of the tests, there will be 80 volunteers from 20 to 59 years old. Then 400 more people over 59 will enter. In all cases, participants have to wait more than six months after being vaccinated for covid-19; no matter which previous immunizer was used. In the clinical trial, however, the volunteers will have been initially vaccinated with the substance in Astrazeneca.

Gazzinelli explains that since the beginning of research with SpiN-Tec, the scientists’ objective was to arrive at a booster vaccine. “We already anticipated that, when the human trials phase arrived, a large part of the population would be vaccinated, which would be a difficulty”, she says. In addition to being designed and produced in Brazil, SpiN-Tec has as a differential the fusion of two coronavirus proteins, to stimulate the immune response. In addition to the spike, used by Sars-CoV-2, the vaccine is composed of the nucleocapsid, the structure that houses the viral genetic material.

Combination

The combination of proteins gave rise to 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 current vaccines is mutations in the spike, which make it difficult to detect the virus and, consequently, reduce the effectiveness of the substances. According to Gazzinelli, the nucleocapsid is much more stable and, therefore, less subject to variations. In the study, SpiN-Tec showed the same efficacy against the delta and omicron variants as the original strain, Wuhan.

Alone, the Brazilian vaccine does not induce the formation of antibodies. However, as a booster dose, the substance stimulates cellular immunity — the response of T and helper cells — and humoral immunity, which produces specific immunoglobulins. Thus, SpiN-Tec ends up acting on two fronts.

In the article published in Nature Communications, the authors report the results of studies in mice, carried out in a laboratory of the Faculty of Medicine of Ribeirão Preto, USP (FMPR-USP) with support from the Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp). ). The animals were genetically modified 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. The guinea pigs were also altered in order to mimic severe covid.

The animals were divided into groups: one part received two doses of SpiN-Tec with an interval of 21 days between them. In the others, the scientists administered a placebo. After a month, the mice were exposed intranasally to a high load of Sars-CoV-2, both in the original version and in the beta, delta and omicron variants.

Protection

“In the group that received placebo, 100% of the animals infected with the Wuhan strain or with the delta died”, Juliana Castro, a doctoral student supervised by Gazzinelli who carried out the pre-clinical tests, told Agência Fapesp. “Mice exposed to the omicron did not die, but developed a significant pathology in the lung. In the immunized group, all the animals survived the three strains and the lung tissue was much better preserved. In addition, we observed a reduction in viral load which varied between 50 and 100 times.”

In a hamster model that mimicked mild covid-19, the vaccine was tested against the original and delta variants, also successfully. 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 convalescent blood (people who have recovered from covid-19), with the same effectiveness.

According to Natália Salazar, a researcher at CTVacinas, the technology used in SpiN-Tec — the combination of the recombinant protein with an adjuvant, which potentiates the immune response — is based on the genetic modification of the E.coli bacterium, which received pieces of the Sars- CoV-2, thus producing the spike and the nucleocapsid. She explains that the method can be used in other diseases. “Before the pandemic, we were already working with this technology applied to diseases such as leishmaniasis and Chagas. The urgency caused by the emergence of covid-19 helped us to develop this solution as quickly as possible”, she says. Currently, CTVacinas is also researching an immunizer for monkeypox.

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