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August 31, 2024. – Two subtypes of human immunodeficiency virus (HIV) can produce recombinant viruses, of which at least 98 different viruses have been identified and sequenced.
It is called the circulating recombinant form (FRC) and is highly prevalent in certain regions, particularly in areas where multiple subtypes predominate, such as Asia and Africa.
However, this is also the case in South America, as announced in recent days by a group of researchers from Brazil, who have publicly discovered a new variant of the HIV-1 type, although it is not yet clear whether it is more transmissible or virulent.
It is a recombinant virus because it combines genes from HIV-1 subtypes B and C, which are prevalent in Brazil. It was discovered in 2019 during the analysis of samples from infected patients at the Salvador Hospital in Bahia state.
The researchers said they named the variant “CRF146 BC” and compared it with genomic information containing HIV gene sequences in public databases, when they found three other samples with the same structure.
Moreover, none of them is the variant’s patient zero, that is, someone who was infected twice.
“What raises eyebrows with the emergence of these recombinant forms is the rate of double infection. According to international agencies, individuals are contaminating and recontaminating,” says Joana Paixão Monteiro-Cunha, co-author of the study.
The study, conducted by the Federal University of Bahia and the Oswaldo Cruz Foundation and published in its journal Memorias, concluded that “the new HIV-1 CRF146 BC is circulating in three different regions of Brazil: the South, the Southeast and the Northeast.”
Specifically, once the phylogenetic analysis was completed, the results showed “a common origin between strains isolated in Rio Grande do Sul, Rio de Janeiro and Bahia,” and so far, the same infections have not been reported in other countries.
Classification
HIV is divided into two main types, each with different groups and subtypes, which in turn may have variants and strains. These types are HIV-1 and HIV-2, the latter of which differs by more than 55% at the genetic level.
The first group is M, N, O and P, and the second group is from A to I. HIV-1 is the most dominant, with 95% of the infections in the world mainly coming from group M, while HIV-2 has groups A and D, but they are mainly spread in West Africa and have no subtypes.
Likewise, M has nine subtypes, from A to K, except E and I, but subtype C is the most common in the world but is uncommon in countries like the United States where B is found.
In this case, the subtype found in Brazil was classified because two subtypes of group M could form hybrids by combining and then spread within the population.
In this regard, when two or more come together, it is because the person was infected with both at the same time, resulting in a recombinant with shared genetic information.
Healthline Media noted that these strains are called mutations because the virus replicates its genetic material. Experts also pointed out that a person may be infected with more than one virus, a so-called “superinfection,” with the new virus replacing the original virus or coexisting with it.
Currently, the prevalence has not been determined, but some believe that the rate of superinfection varies between 0 and 7.7% per year.
background
In 2022, a new “hypervirulent” variant called BV subtype was discovered for the first time, which showed higher viral loads in the blood, greater transmissibility, and a rapid decrease in T-CD4 defense cells.
The study, conducted by the University of Oxford in the UK and published in the journal Science, confirmed infections in 109 people from the Netherlands, Switzerland and Belgium. The variant appeared in the Netherlands in the 1980s and 1990s, spread in the 2000s and began to weaken in the 2010s. Current treatments are effective against it.
On the other hand, among the indigenous people of Jaguapiru and Bororo, in the Brazilian state of Mato Grosso do Sul, the HIV transmission rate was 0.93% in 2023, compared to 0.13% in 2012.
HIV in numbers
UNAIDS estimates that by the end of 2023, between 930,000 and 1,100,000 people (adults and children) in Brazil will be living with HIV, implying an infection rate of 0.6 among people aged 15 to 49.
The latest statistics, as reflected on the organization’s website, show that as of the end of last year, nearly 40 million people worldwide were suffering from the disease, of which 1.3 million were infected.
Likewise, 630,000 people have died from AIDS-related illnesses, and the historical number of people infected with AIDS worldwide since the pandemic began in the 1980s is estimated to be between 71 and 112 million.
On the other hand, the death toll ranged from 35.7 to 51.1 million, of which 53% were women and girls, including 1.4 million below the age of 14 years.
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