FAPESP-funded startups are developing COVID-19 vaccines29 de junho de 2021
By Elton Alisson and Karina Toledo | FAPESP Innovative R&D – Two startups with support from FAPESP's Innovative Research on Small Business Program (PIPE) are developing candidate vaccines to combat COVID-19.
One of them is Imunotera Soluções Terapêuticas, a spinoff from the University of São Paulo (USP).
The project under the leadership of Luana Raposo de Melo Moraes Aps, co-founder of Imunotera, aims at developing a DNA vaccine that will induce cellular immune responses to SARS-CoV-2 based on the genetics of the Brazilian population. The strategy focuses on designing target sequences that include the viral epitopes most easily recognized by T lymphocytes, which produce cytokines or directly kill infected cells.
The researchers adapted an existing T-cell generating technology used to develop, also with the support of PIPE-FAPESP, a DNA vaccine and purified recombinant protein that activates the immune system – both have proved capable of combating HPV-induced cervical cancer. The immunotherapy drug in the form of a recombinant protein has been tested with good results on patients with precancerous lesions caused by HPV treated at Hospital das Clínicas, the hospital complex run by the University of São Paulo’s Medical School (HC-FM-USP).
To develop a COVID-19 vaccine, they first selected the most frequent human leukocyte antigens (HLAs) in the Brazilian population to identify the epitopes most easily recognized by T lymphocytes, especially the CD8+ type. HLAs are a special group of proteins located on the surface of almost all cells in the body.
“Initially we focused on the Brazilian population because no COVID-19 vaccines were available in Brazil when we submitted the project, but the vaccine can be used anywhere in the world. The HLAs we selected are frequent in the American and other populations, for example,” Aps told Innovative R&D. One of the advantages of basing the vaccine on the genetic profile of a population is that the immune response is better targeted, increasing the effectiveness of the vaccine, she added.
The vaccine has been tested on mice, which were given two doses, and their immune response was assessed two weeks later. The results of this proof of concept in terms of immunogenicity were satisfactory. The researchers now plan to perform tests on animals infected with SARS-CoV-2 and to begin clinical trials in 2022.
According to Aps, one of the main advantages of this vaccine compared with first-generation vaccines could be its capacity to neutralize variants of concern, as the relevant mutations in SARS-CoV-2 occur in the spike protein, which is not the vaccine’s target.
“This will have to be confirmed by genetic analysis, but the formulation we’re developing has the potential to transcend the limitations of existing vaccines and combat all variants, inducing a robust cellular response in the Brazilian population,” she said.
The vaccine will be injectable, administered in two doses, and stable at room temperature.
Besides the DNA vaccine against COVID-19, the startup is developing an RNA vaccine that looks highly promising, according to Aps.
The firm uses a vaccine platform based on an attenuated live bacterium, which briefly colonizes the lymphoid organs associated with the intestines, as well as secondary lymphoid organs in animals. “The vaccine’s genetically modified vector contains genes that induce expression of SARS-CoV-2 proteins. If the plan succeeds, this combination will stimulate sufficient humoral and cellular immune responses to prevent the development of COVID-19,” Trevisani said.
Because the vector is a live bacterium, this initial stage of the research depends only on a fermenter to grow bacteria to scale. The methodology is tried and tested. “This platform has been used to prevent horse pneumonia caused by Rhodococcus equi, with patent applications in Brazil and elsewhere,” he explained.
In the case of equine pneumonia, all the tests and protocols used throughout the research project show that the vector colonizes the lymphoid organs associated with the intestines and secondary lymphoid organs long enough for the maturation and selection of clones that are highly effective in controlling infections caused by R. equi.
In addition, the researchers detected robust production of IgA (immunoglobulin A, which protects mucosa) and IgG (immunoglobulin G, important and widely dispersed for opsonization and neutralization of infectious agents), as well as a strong cellular immune response capable of killing infected cells.
“Based on our prior experience, we expect the same to happen with prevention of SARS-CoV-2,” Trevisani said. “We’re currently working on construction of the vaccine platform and measuring expression. The timetable calls for animal testing to begin in August 2021. However, our experience with the platform for R. equi pointed to strong humoral, mucosal and cellular immune responses. In fact, the scientific community in the field considered it one of the top five vaccine proposals for the disease.
“The main advantage of the technology is its applicability. The vector can be administered orally and doesn’t require needles or trained professionals. The scale of vaccine rollout can be huge compared with intramuscular immunization. Also, the fact that it’s based on a live bacterium means the formulation can be lyophilized and used in remote areas of Brazil and the world without requiring cold chain transportation.”
The team does not yet have plans for clinical trials. “Everything depends on the efficacy and safety demonstrated in the preclinical trials involving animals,” Trevisani said.
Besides these startup-developed vaccine candidates, FAPESP also supports the Phase 3 clinical trial of CoronaVac – the COVID-19 vaccine produced in Brazil by Butantan Institute – and currently funds six other research projects to develop COVID-19 vaccines.
Four of them are under development at the University of São Paulo (USP), and the other two at Butantan Institute (read more at agencia.fapesp.br/36222).
At the Heart Institute (InCor) of the University of São Paulo’s Medical School (FM-USP), a team led by Jorge Elias Kalil Filho is developing a DNA vaccine to be delivered by nasal spray. It will combine part of the spike protein used by SARS-CoV-2 to bind to a receptor and infect human cells with T epitopes, viral antigens that are recognized by the immune system. The goal is to induce a response by neutralizing antibodies in parallel with strong cellular immunity, including cytotoxic T CD8+ lymphocytes, which kill infected cells, and T CD4+ lymphocytes, which assist the production of antibodies and the cytotoxic response.
Another research group, led by Ricardo Tostes Gazzinelli at the University of São Paulo’s Ribeirão Preto Medical School (FMRP-USP), is developing a bivalent intranasal vaccine using the influenza virus to express the SARS-CoV-2 spike protein.
The other project in progress at ICB-USP, entitled “Development of SAPN nanovaccines against SARS-CoV-2 using S and N as antigens”, is part of the postdoctoral research of Mariana Favaro, with Luis Carlos de Souza Ferreira as principal investigator.
“Our project concerns genetic modification of viral proteins so that they acquire the capacity to self-assemble in a nanoparticle with a three-dimensional structure that closely resembles the morphology of viruses and can therefore interact more effectively with the immune system,” Favaro said. The strategy mimics characteristics of the virus, such as size and repeating antigen presentation, that are naturally recognized by the immune system as signs of pathogens and activate an immune response.
The other project is led by Luciana Cezar de Cerqueira Leite and combines two technologies, based on bacterial outer membrane vesicles (OMVs) – nanoparticles that mimic an infection and efficiently activate the immune system – combined with SARS-CoV-2 proteins. The aim is to induce a broad immune response involving both antibodies and defense cells.