Almost a year and a half after the World Health Organization classified the spread of Covid-19 in the world as a pandemic, scientists have yet to find an effective drug to stop the reproduction of the coronavirus in cells. Now, a discovery by Brazilian researchers can help change this scenario. Scientists from the Chemistry Institute of the State University of São Paulo (Unesp) of Araraquara revealed that the venom of the Brazilian snake Jararacuçu, common in states like Rio Grande do Sul, Minas Gerais and Bahia, contains a molecule capable of inhibiting up to 75% of such snakes. virus capacity.
Unprecedented, the high rate would give time for the infected organism to create antibodies, preventing the spread of the disease. The results of this study were recently published in the international scientific journal Molecules.
The molecule isolated in the snake is a peptide, a piece of protein, with antibacterial and antiviral action.
— This peptide has the ability to bind to a virus enzyme (the PLPro) which is responsible for processing some molecules that make viral reproduction. So, if we inhibit the action of this enzyme, we reduce the multiplication of viral particles — explains Eduardo Maffud Cilli, a professor at the Institute of Chemistry and one of the authors of the study.
The enzyme that is inhibited by the snake venom peptide is present in all coronavirus variants discovered so far. It is not part of the structure formation of the virus – which often mutates to better adapt to the host. Its function is to help multiply already installed viruses.
— The gene that is responsible for the production of this enzyme appears in all variants. This shows that this peptide has great potential to work against any of them – says Salmo Raskin, geneticist physician and director of the Genetika Laboratory, in Curitiba, who did not participate in the study.
Importantly, only the molecule has action against the coronavirus. The rest of the Jararacuçu snake’s venom has no ability to stop the viral replication of Sars-Cov-2. The bite of this snake can cause hemorrhage, swelling and tissue destruction in the injured region. According to Fiocruz, the jararacuçu is responsible for 90% of poisoning by snakes in Brazil, being the snake that bites most human beings in the country.
The first stage of the work consisted of reproducing in the laboratory the peptide found in the venom of the Jararacuçu snake.
– We analyzed a toxin from the venom and realized that a part of it could have an activity against the coronavirus – details Cilli.
Scientists placed the peptide in laboratory-grown monkey cells. An hour later, they selected a sample of the coronavirus and infected the primate cells. After two days, the researchers observed that the coronavirus did not reproduce with the same speed observed under normal conditions. This stage of the study was carried out at the Institute of Biomedical Sciences (ICB) at USP, in São Paulo, where a sample of the coronavirus is isolated.
The next step was to understand the mechanism that hindered the viral replication of Sars-CoV-2. With the partnership of USP’s São Carlos Institute of Physics (IFSC), which contained the PLPro enzyme, the Unesp researchers then observed that the peptide was able to inhibit viral replication by up to 75%.
The study is promising and has yet to be tested in humans. According to Cilli, this peptide is safe even in high concentrations. In addition, this peptide is easy to synthesize, which would simplify large-scale production if it were to become a Covid-19 drug.
The next step in the work is to assess the efficiency of other dosages of the molecule and whether it is capable of performing other functions in the human cell, such as preventing the virus from infecting it. Scientists also want to analyze what the cells’ reaction would be if they were first infected with the coronavirus to later receive the peptide.
The new compound could even replace a current treatment, monoclonal antibodies, a type of “artificial” antibody that is injected into patients with severe Covid-19, fighting the replication of the coronavirus. However, in addition to being expensive, this treatment loses its effectiveness, since its attack target is the Spike protein, which usually undergoes important changes with each new variant.
— We have seen that the pandemic will not end only with vaccines. So, this study comes at an appropriate time because it is important to try to develop drugs to prevent the virus from replicating – evaluates Raskin.
It is not uncommon for molecules found in animal poisons to serve as medicines to treat diseases that affect humans. From the poison of Jararaca, for example, captopril was developed, one of the most popular remedies in the treatment of hypertension. Exenatide, on the other hand, is an anti-diabetes drug produced based on a hormone found in the saliva of the Gila Monster lizard. Thus, Cilli makes an alert:
— These fires throughout Brazil destroy microorganisms and plants that can give us a cure for various diseases.