A particularly virulent variant of the HIV virus has been discovered

Scientists have identified a particularly virulent variant of HIV in over 100 people in the Netherlands. Compared to other variants, the so-called VB variant, if left untreated, leads to a significantly higher viral load and damages the immune system of those affected twice as fast. Moreover, it is especially contagious. Genetic analyzes show numerous mutations throughout the virus genome, so scientists have not yet been able to pinpoint exactly what is responsible for the increased virulence. The variant was probably created in the 1990s. Because it can be well controlled with popular HIV medications, researchers emphasize that early diagnosis is important.

Worldwide, about 38 million people are infected with HIV. If untreated, the virus causes the death of CD4 immune cells, which ultimately leads to the clinical picture of AIDS. With antiretroviral drugs, it is now possible to inhibit viral proliferation in cells to such an extent that, with optimal therapy, HI viruses cannot be detected in the blood of those affected, their immune systems function normally and they are very unlikely to infect other people. While in Germany, as in other Western countries, over 90 percent. people diagnosed with HIV take appropriate medications, access to diagnostics and therapy is limited in other parts of the world.

Variant in the Netherlands

As with the Sars-CoV-2 coronavirus, in the case of HIV, there is also a risk that mutations will result in new variants that are more aggressive, contagious, or resistant to drugs. “Therefore, continuous surveillance of the virulence of HIV is important to health worldwide,” writes a team led by Chris Wymant of the University of Oxford. Researchers are therefore studying the virus genome in thousands of HIV-infected people in Europe and Uganda in a long-term international study.

In this study, the Wymant team first identified a new variant in 17 HIV-infected people that was associated with particularly high viral load and rapid decline in CD4 cell counts. 15 of the 17 people were from the Netherlands, one each from Switzerland and one from Belgium. To track down the variant, Wymant and his colleagues also analyzed data from more than 6,700 people infected with HIV in the Netherlands. In fact, they were able to identify a variant they called the VB variant (virulent subtype B) in another 92 people.

mechanism unclear

“Before treatment, these people had a viral load of 3.5 to 5.5 times, and CD4 cell counts were declining twice as fast as other HIV-infected people,” the researchers said. While the number of immune cells has dropped to the point of other HIV variants that it takes about six to seven years for AIDS to break out, scientists estimate that it takes two to three years for the VB variant to do so, even in older people infected . faster. According to the researchers, the rapid decline in CD4 cell counts is due not only to the increased viral load but also to the fact that each individual VB variant virus is more cell-damaging than other HIV variants.

Scientists have not yet been able to answer why this is happening. “The genotype of the VB variant is characterized by multiple mutations distributed throughout the genome, which means that, based on current data, it is not possible to identify a single genetic cause of increased virulence,” they write. They identified one of the numerous mutations associated with the increased ability to damage CD4 cells. However, this mutation also occurs in other already known variants. “This makes it unlikely that this mutation alone is the dominant mechanism for the virulence effect we observe,” the researchers say.

mutations from the 90s

Genetic data suggest that the new variant was not created by recombining existing HIV strains, but by new mutations. They were probably created in the 1990s. In a 1992 sample from Amsterdam, scientists found a virus variant that was likely a precursor to the VB variant found in newer samples. Genetic comparisons suggest that the VB variant spread faster than other HIV variants until the late 2000s. However, since 2010, prevalence is likely to decline again.

Demographically, the 109 identified VB carriers did not differ from other HIV carriers. 82 percent are men who have sex with men, 86 percent. was born in Western Europe. The age of the people affected by the disease and the assumed type of transmission did not differ either. The temporarily accelerated spread of the VB variant is therefore probably actually due to the properties of the virus itself and not to the specificity of the infected people.

early detection important

According to the results, there are almost no drug-resistant mutations in variant VB. Since almost all infected people are treated in the Netherlands, and the VB variant appears to be as well controlled with drugs as the other variants, researchers found no difference between VB infected persons and other HIV-infected persons in terms of health status and mortality. . After starting treatment, those infected with VB regained their immune systems at a rate similar to that of other HIV-infected individuals.

“Our findings highlight the importance of the World Health Organization’s guidelines that people at risk of HIV should have access to regular testing to enable early diagnosis followed by immediate treatment,” says Wymant’s colleague Christopher Fraser. “This limits the length of time HIV can damage a person’s immune system and put their health at risk. It also ensures that HIV is suppressed as quickly as possible, preventing it from being passed on to other people. “

Source: Chris Wymant (University of Oxford) et al., Science, doi: 10.1126 / science.abk1688

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