SAO PAULO – Brazilian scientists are using an approach for developing a COVID-19 vaccine that runs counter to the methods employed thus far by the pharmaceutical industry and groups of researchers in other countries.
Their project is being carried out at the immunology laboratory of the University of Sao Paulo Medical School’s Heart Institute, where specialists in different research areas have been working over the past month on a vaccine based on artificial particles that resemble severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Dr. Jorge Kalil, the laboratory’s director and project coordinator, told EFE.
Thus far, most of the experiments conducted in Germany, the United States and other countries have focused on developing vaccines based on the pathogen’s genetic material, a method that involves incorporating synthetic messenger RNA (ribonucleic acid) molecules into the vaccine.
But Kalil, currently in quarantine after a close family member tested positive for the coronavirus, said that path will not produce the desired results.
“We believe that method, though safe, does not induce a very strong immunological response, and generally when we’ve tested that RNA vaccine on human beings the response has been weak,” he said.
The idea is to “not use genetic material” due to the lack of sufficient existing information about SARS-CoV-2 and instead develop structures similar to the virus, project head Dr. Gustavo Cabral said.
“We don’t know that much about the virus, and the information we have is not sufficient for us to envisage a vaccine using genetic material,” he said.
The Brazilian team’s approach entails using molecular biology techniques to develop empty, non-infectious multi-protein structures known as virus-like particles (VLPs) that are easily recognizable by immune system cells.
“The vaccine we’re proposing resembles the protein coat of a virus. It has the external part of a virus, but it doesn’t have nucleic acid inside, which is what allows it to multiply,” Kalil said.
“And we can make it so there are pieces of coronavirus protein on the surface of that particle, so the immune system perceives it as if it were a virus, responds forcefully and is capable of producing anti-bodies against that part of the coronavirus we want to attack,” he added.
Different research projects carried out to combat SARS-CoV-2 have focused on the means of deactivating that coronavirus, an approach that dates back to efforts to fight two earlier coronaviruses species (SARS-CoV in 2002 and MERS-CoV in 2012).
The key appears to lie in the coronaviruses’ characteristic spikes, which in fact are clumps of proteins, Kalil said.
“The idea is to develop an immune response against that specific part,” since that is what “facilitates the coronavirus’ entry into the cell,” said Cabral, who spent the past five years in Europe developing vaccines against the Zika virus and returned to Brazil in February to develop vaccines against a streptococcus infection and the chikungunya virus.
But the outbreak of the novel coronavirus forced him to divert those efforts.
The mission now is to generate some type of antibody against the coronavirus’ crown-like spikes that impedes it from entering and infecting human cells.