With information from Bruno Bocchini, from Agência Brasil

Research from the University of São Paulo at Ribeirão Preto Medical School (FMRP-USP) has shown how a particular virus makes leishmania – the protozoan that causes leishmaniasis – to become more aggressive to humans. Cutaneous leishmaniasis, transmitted to humans by the bite of the straw mosquito females, causes localized lesions on the skin. However, in more severe cases, when wounds spread, lesions also appear on the mucous membranes, often on the nose, mouth and throat, and may disfigure the patient’s face. At this stage, known as mucocutaneous leishmaniasis, the disease can become lethal.

Researchers were already aware that leishmania, when infected with the Leishmania RNA virus (LRV), was capable of developing the most severe cases of the disease. USP research has now shown how the virus enables protozoan to develop aggressively.

“When leishmania infects people, they get an arm wrestling. She wants to survive and our immune system trying to eliminate the parasite. But when leishmania has the virus, it ‘shuts down’ some of the parasite’s mechanisms that fight the immune system, ”says research author Renan Carvalho, a scientist at the Department of Cellular and Molecular Biology and Pathogenic Bioagents at FMRP-USP. .

According to research, when LRV-infected leishmania invades the human body, the virus activates a receptor on cells called TLR3, which causes the immune system to start producing interferon type 1. , in turn, induces autophagy of human cells, ie the process of degradation and recycling of cell components.

As a result, human cells become more vulnerable, as the presence of interferon prevents the action of inflammasome, a set of immune system proteins that fight leishmania.

“Because this protein that kills leishmania is being silenced by the virus, leishmania can survive better, proliferate better and cause that form of the most serious disease, mucocutaneous leishmaniasis. The parasite migrates to people’s faces, both to the mouth and nose, and disfigures the patient’s face, ”says Carvalho.

According to the researcher, the study paves the way for new ways to combat leishmaniasis and treat patients. “We propose that from now on, the patient who arrives with suspected leshmaniasis should be diagnosed not only to see if he has leishmania, a parasite, but also to have a molecular analysis to see if leishmania has the virus. ”Says Carvalho.

According to the scientist, if diagnosed with leishmania carrying the virus, the patient should receive, in addition to conventional treatment against leishmaniasis, drugs that can also combat the action of the virus. This medication, however, is still in the research phase.

According to the Ministry of Health, in Brazil about 21,000 cases of cutaneous leishmaniasis are registered annually. The North region has the largest number of cases, followed by the Midwest and Northeast.

The research of the School of Medicine of USP was conducted at the Center for Research on Inflammatory Diseases (CRID) in Ribeirão Preto (SP), a Center for Research, Innovation and Dissemination (Cepids) supported by the São Paulo State Research Support Foundation. Paulo (Fapesp).