Early B cell response prevents the oropouche virus from reaching the brain

Research conducted in mice has identified that the rapid response of a particular type of defensive cell is essential to control oropouche infections and prevent serious neurological damage. Without treatment, “oropouche fever” causes symptoms, including headaches, muscles and joints, skin rashes and vomiting. In severe cases, it can lead to meningitis and encephalitis. Pregnant women are at risk of complications, including miscarriage.

These findings will contribute to future studies for the development of treatments and vaccines against the disease. Oropouche virus is considered a neglected arviomy transmitted by Midge Culicoides Paraensis When infected with Oropouchence ortobunyavirus (Orov). Between January and early June of this year, Brazil recorded an increase of 60% in cases compared to the same period in 2024 – about 11,500 confirmed cases (compared to 7,200 last year) and four deaths. This set in less than six months is close to the number of cases recorded throughout last year – 13,800 according to the Brazilian health ministry.

Scientists have discovered that B cells in the spleen limit zone are the first lymphocytes to act in the body after infection, producing rapidly antibodies that prevent the virus from spreading and reaching the central nervous system and brain. This early antibody production depends on a protein, Myd88, which activates the response, contributing to the neutralization of oropouche.

The results of the study are published in the journal ebiomedicineby the Lancet Group (United Kingdom).

This study gave a very important result, promoting our understanding of how this virus acts in two ways. First, from a mechanistic point of view, analyzing the marginal zone B -cell road, which has been slightly explored with compared to viral arthropod infections. This helps us to understand the mechanisms associated with encephalitis and those who protect the body from the virus access to the central nervous system. The second point is related to the ability to treat and vaccines, indicating that antibodies act quickly. This suggests that the therapeutic window may not be so large, requiring rapid action in the early stages of infection. ”

José Luiz Proença Modena, one of the study advisers and professor at the Institute of Biology at Campinas State University

Modena is the coordinator of the Laboratory Laboratory (LEVE) at Unicamp. The Leve is supported by FAPESP, which also funded research through three other projects (16/00194-8, 17/11931-6 and 14/50938-8).

The lead author of the article, researcher Daniel Teixeira, points out that the threat of restaurants and epidemics makes it even more urgent to understand the mechanisms of the Oropouche infection. “We have managed to shed light on a virus that is still known to the general public. By studying it, it is possible to predict processes that can be activated in the body and therefore science can be prepared to deal with epidemics.”

Earlier this year, another study published in the magazine Infectious diseases – Also involved in scientists from LEVE – showed that the Oropouche fever, documented in South America since the 1950s, showed an explosion of cases between November 2023 and June 2024 in four countries: Brazil, Bolivia, Colombia and Peru.

In Brazil, automatic infections were recorded in areas that were previously non -endemic in all five areas of the country, with cases in 21 states. The incidence rate has increased almost 200 times compared to the last ten years. “The symptoms of the disease are similar to dengue and zika and can be confused. Therefore, oropouche tests are also essential for epidemiological monitoring,” Modena adds.

Following the increase in cases, the Ministry of Health informed the rules on the surveillance and control of the Oropouche virus in Brazil, which is now subject to compulsory reference – that is, all suspicions or confirmed cases must be reported within 24 hours.

Partnership

The project was conducted by a group of 30 researchers from various institutions. In addition to Unicamp, the team included scientists from the University of Sao Paulo (USP), the Federal University of Roraima and Fiocruz Amazônia (also in Brazil), the University of Cardiff (United Kingdom), the University of Kardaki and the United States.

“We have benefited from the efforts of foreign researchers, but most of the project-the real practical work-did in Brazil by postgraduate students.

The group conducted immunophone experiments, passive serum transfers and transfers of adopted cells to determine how early antibodies and B cell reactions control the copy of the virus and the spread to the central nervous system after infection. The mice produced special antibodies against orov within six days of infection.