The human immunodeficiency virus (HIV) is responsible for AIDS. It is believed to affect around 38 million people worldwide, including 1.7 million children. 680,000 patients died of an AIDS-related illness in 2020.
HIV is a retrovirus, that is to say an RNA virus capable of integrating into the genome of the host cell. When it enters an individual, it colonizes immune cells with the CD4 marker on their surface. In just a few hours, it accumulates in human cells. The latter become reservoirs of latent viruses, for life.
As the virus leads to the disappearance of immune cells called CD4+ T lymphocytes, the patient’s immune system becomes less and less effective. The patient is then susceptible to all types of infections and certain cancers. This is called acquired immunodeficiency syndrome, AIDS. The virus is transmitted through blood, semen, vaginal secretions and breast milk. There are two types of HIV: HIV-1 and HIV-2. In France, an overwhelming majority of infections are due to HIV-1.
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Credits: UNAIDS.
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HIV variant: 3 to 5 times higher viral load
Researchers at the University of Oxford have discovered the existence of a variant of HIV, nicknamed VB (for virulent subtype B). This is a new, very virulent strain circulating in particular in the Netherlands. 109 carriers of this variant have already been identified in the country.
Like SARS-CoV-2, HIV is capable of accumulating mutations. In the case of the VB variant, the many mutations in its genome give it greater virulence and transmissibility.
Thus, individuals carrying the variant have a quantity of virus in the blood 3.5 to 5.5 times higher than patients carrying other strains of HIV. Consequences: the risk of transmitting HIV to other people is greater.
In addition, the decrease in the number of immune cells in patients is twice as rapid with this variant. The latter are thus exposed to the risk of developing AIDS earlier.
However, antiretroviral treatments still seem effective, by blocking the multiplication of the virus in the cells. From the start of therapy, carriers of the variant saw their immune system recover in the same way as with other strains of HIV.
The authors of the study insist on the importance of multiplying blood tests in populations at risk in order to detect people carrying this variant as quickly as possible. As the immune system declines more rapidly with this strain, it is therefore necessary to intervene with treatment as early as possible.
Researchers now want to understand how this virus can be more virulent and transmissible, in order to adapt new generation antiretroviral treatments.
