Brazil creates first vaccine against schistosomiasis – 06/08/2023 – Health

Fiocruz (Oswaldo Cruz Foundation) is in the final stage of clinical trials of the world’s first vaccine against schistosomiasis –or water belly– and is awaiting pre-qualification by the WHO (World Health Organization).

The vaccine is the first developed in the world against a helminth, a group of parasitic worms responsible for about 1 in 6 of the so-called neglected tropical diseases, according to the health agency.

The vaccine, called Schistovac (Sm14), was developed with Brazilian technology, produced at the Experimental Schistosomiasis Laboratory of the Oswaldo Cruz Institute (IOC). The vaccine is considered one of the health researches prioritized by the WHO.

The discovery of the vaccine was led by researcher Miriam Tedler, linked to the IOC/Fiocruz. She claims that a technology transfer agreement has already been signed for production and development at Fiocruz’s Instituto Biomanguinhos. “Fiocruz assumed the responsibility [de produção] and is interested, with the support of the Ministry of Health, in developing this vaccine that will be unique in the world and made 100% in Brazil”, he said.

The vaccine study was the result of a PPP (public-private partnership) between the institute and the American company Orygen Biotecnologia SA for the development and production of the human vaccine. It was developed from the antigen –or the molecule against which you want to generate an immune response– discovered and isolated in the Fiocruz laboratory.

The research received support from CNPq (National Council for Scientific and Technological Development), linked to the Ministry of Science and Technology, and from Finep. In addition, the production of vaccine doses for use in humans at the Fiocruz plant in Rio de Janeiro receives support from the Ministry of Health. The institute registered the patent for the immunizer in several countries, including Brazil and the United States.

In preclinical tests on laboratory animals, the vaccine showed a reduction of more than 90% in the infection of rats and rabbits by Schistosoma mansoni. In humans, the vaccine proved to be safe and well tolerated, with the main effect being pain at the injection site and without the occurrence of serious adverse events.

Human testing began on 20 subjects in Rio de Janeiro in 2011. Subsequent stages 2 and 3 of clinical trials were conducted in Senegal. Preliminary results from the last stage of the trial show that the vaccine is safe and produced an immune response against S. mansoniwhich causes schistosomiasis.

If approved, the vaccine would be the first in the world to protect against a worm. The expectation is that the results presented to the global health entity will lead to the so-called pre-licensing, which would be a WHO endorsement for the scale production and application of the immunizer in priority areas. “If approved, we will obtain a seal for Schistovac to be introduced in endemic countries, thus being able to represent an important health tool in priority countries”, says the researcher.

Schistosomiasis, also known as water belly, is a neglected parasitic disease, linked to poor sanitary conditions and lack of basic sanitation. It occurs by schistosome infection through snail eggs (transmitter) containing larvae (cercariae), which penetrate human skin. In the bloodstream, the larvae lose their tail and become cysts (schistocytes), which will lodge in organs, mainly the liver, where they grow. Adult worms may travel to veins in the intestine or rectum and to the bladder, giving the characteristic “water belly”. The cycle is completed with the elimination of eggs through feces and urine.

Despite having low mortality, schistosomiasis is one of the tropical diseases that most cause loss of quality of life (morbidity). According to WHO, there is an estimate that 200 million people are infected every year by schistosomiasis, but another 800 million live in high-risk areas, thus reaching 1 billion cases per year.

The endemic regions are mainly the countries of Africa and the Americas. In the case of the Americas, around 95% of cases of schistosomiasis occur in Brazil. According to the Ministry of Health, there are currently more than 1.5 million Brazilians at risk of contracting schistosomiasis.

Vaccine studies against schistosomiasis began in the 1980s, when people were looking for an antigen capable of protecting against veterinary parasitic infections in cattle and sheep. With the observation of the mechanism of infection and protection of the parasite Fasciola hepaticathe researchers looked for a similar molecule in the Schistosoma mansonithe main species that causes schistosomiasis in Africa and Latin America.

The vaccine contains the Sm14 protein, present in the Schistosoma, modified. This protein plays an important role in transporting fats (lipids) necessary for the parasite’s cellular functions. However, a change in Sm14 prevents the transport of these fats. As the parasite depends on them to survive and is unable to produce them on its own, this change prevents its proliferation.

According to Tedler, there is an agreement between the agencies involved in the research and development of the vaccine for it to be produced and offered to endemic areas at low cost. “From the beginning, our partners have been committed to producing the antigen [nome dado ao princípio ativo da vacina] in a context of humanitarian vaccine, aiming at a wide distribution to endemic countries and with limits of gain”, he concluded.