A team of UK researchers has discovered that the VB variant of HIV may be more virulent and damaging than other strains of the disease.
A study led by researchers at the University of Oxford’s Big Data Institute provides unprecedented insights into the VB variant, identifying it causes a higher viral load, is more damaging to the immune system and is more transmissible than other strains.
The COVID-19 pandemic has illustrated how novel genetic mutations in viral genetic sequences can significantly increase the transmissibility and severity of a virus; now, it appears the same has occurred in the HIV-1 virus, which already affects 38 million people worldwide and has caused 33 million deaths to date.
Origins of the VB variant
The VB variant was first discovered during the BEEHIVE project – an ongoing study collecting samples across Europe and Uganda, finding 17 HIV positive individuals with the strain. Due to 15 of these people being from the Netherlands, the team analysed data from a cohort of over 6,700 HIV positive individuals in the Netherlands, identifying 92 people with the VB variant, taking the total to 109.
By examining the genetic mutation patterns in the samples, the team estimated that the VB variant first appeared in the late 1980s and 1990s in the Netherlands, spreading more rapidly than other HIV variants during the 2000s before declining since around 2010. Despite there being widespread treatment in the country for HIV, the strain still spread across the nation quickly.
People in the Netherlands with the VB strain demonstrated the typical characteristics of individuals living with HIV, including age, sex, and suspected mode of transmission. This signifies that the VB strain has increased transmissibility due to the properties of the strain itself, instead of a characteristic of people with the virus.
Comparing the strains
Analysis from the University of Oxford team identified that people infected with the VB variant had notable differences before antiretroviral treatment than people infected with other strains. VB variant patients had a viral load between 3.5 and 5.5 times higher, CD4 cell decline (damage to the immune system caused by HIV) was also twice as fast, increasing the risk of developing AIDS earlier. Finally, individuals with the VB variant showed an increased risk of transmitting the virus to others.
Nevertheless, after treatment, the variant had a similar immune system recovery and survival time to other HIV variants. However, the VB strain can cause a rapid decline in immune system strength, making early diagnosis and treatment vital.
The team said that further research is required to fully understand the mechanisms in the VB variant that make it more transmissible and damaging to the immune system and may help design new targets for next-generation antiretroviral medications. Due to the strain comprising many mutations throughout the genome, a single genetic cause cannot be identified yet.
Lead author Dr Chris Wymant, from the University of Oxford’s Big Data Institute and Nuffield Department of Medicine, said: “Before this study, the genetics of the HIV virus were known to be relevant for virulence, implying that the evolution of a new variant could change its impact on health. Discovery of the VB variant demonstrated this, providing a rare example of the risk posed by viral virulence evolution.”
Senior author Professor Christophe Fraser, from the University of Oxford’s Big Data Institute and Nuffield Department of Medicine, added: “Our findings emphasise the importance of World Health Organization guidance that individuals at risk of acquiring HIV have access to regular testing to allow early diagnosis, followed by immediate treatment. This limits the amount of time HIV can damage an individual’s immune system and jeopardise their health. It also ensures that HIV is suppressed as quickly as possible, which prevents transmission to other individuals.”
