Different HIV strains demand ‘tailor-made’ prevention for each region


The potential for dissemination of different HIV strains goes far beyond the biological specificities of each virus. Social particularities and cultural habits of populations significantly influence the dissemination of subtypes. Therefore, it is urgent to create specific public policies for each region of Brazil.

The conclusions are part of a new work, published in the journal Scientific Reports, by the Nature group, carried out in partnership by Brazilian and Portuguese researchers.

Using different bioinformatics tools, the group analyzed an extensive database of patients diagnosed with the AIDS virus in Brazil. The researchers analyzed the genetic information from the viruses as well as clinical data from the patients.

From there, scientists focused on the spread of the two main HIV strains in the world: the B and C subtypes.

While B is more prevalent in Europe and the Americas, C is dominant in South Africa, Ethiopia and India. In Brazil, type B is more present throughout the country, with only one exception: the southern region, where the domain belongs to lineage C.

Although previous works had already referred to the greater presence of subtype C in the southern states, the degree of regional separation between infections by the two strains surprised the authors of the work.

“It’s quite impressive. It’s as if there was a wall separating it. Subtype B cannot establish itself in the South as well as C”, explains physician Bernardino Geraldo Alves Souto, a researcher at UFSCar (Federal University of São Caetano).

Nuno Osório, coordinator of the work at the University of Minho, in Portugal, reports that the scientists then went to investigate the motivations behind the dominance of subtype C in southern Brazil.

“The main hypothesis in our study is that it is the social and behavioral conditions in the two regions that lead to this: that in one case there is a domain of subtype B and, in the other case, a domain of subtype C”, he reports.

The research indicated that both strains reach high viral loads when patients are not being treated, but that type C takes longer to manifest the first symptoms of the disease.

Symptoms related to decreased immunity have traditionally been an important motivation for people to try to test for HIV.

Without diagnosis and medication, which can bring the viral load down to non-transmitted levels, many infected with type C can spend extended periods of time transmitting the virus.

For reasons that are not yet fully understood by scientists, this and other works indicate that subtype C is also easier to infect women and young people.

Type B, on the other hand, seems more adapted to transmission between men who have sex with men.

In the researchers’ assessment, the culture of women’s repression, tolerance for extramarital relationships and the persistence of cross-breastfeeding, especially in more rural areas, creates a favorable environment to favor the spread of subtype C.

“In Brazil, gender oppression against women still prevails, especially in more rural areas, with a more traditional culture, as in many parts of the South. Women are very socially subordinated, but also sexually within the home. The power of sexual negotiation of women for their protection, such as asking for the use of condoms, is low”, says Bernardino Souto, from UFSCar.

“There is a certain hidden tolerance, that men need and should have extramarital relationships. This favors men bringing HIV into the home and transmitting HIV to women,” he adds.

Taking this into account, and as HIV is not unique, researchers are calling for the creation of plans to fight the virus that take into account regional particularities.

In the specific case of the South region, the group also asks for the intensification of screening tests, with special attention to women and young people, as well as awareness-raising actions about the risks associated with cross-breastfeeding.

The researchers also highlight the potential risk associated with dissemination in lineage C to other regions with similar sociocultural characteristics.

“We have observed that subtype C has gained entry into the North region, in the Amazon region”, warns the professor at UFSCar, drawing attention to the difficulty in accessing tests and the typical prevalence of cross-breastfeeding in less urbanized areas.

For Nuno Osório, from the University of Minho, these results identified among the Brazilian population can help in the formulation of public policies in other countries as well.

The Portuguese scientist also praised the quality of the material provided by the Brazilian Ministry of Health, and stated that Brazil has unique conditions to allow for a comparative analysis between the different types of HIV.

“Brazil has the conditions to carry out this study, to study the two most important HIV subtypes in the world, which perhaps do not exist anywhere else in the world. The same country has border regions with different prevalences, with the South being dominated by subtype C and the rest of the country by B”, explains Osório.


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