HIV continues to replicate in the body even if it’s undetectable in the blood after antiretroviral treatment, scientists have discovered.
It explains how the virus rapidly bounces back – and keeps growing – after a patient stops taking antiretroviral drugs.
Study author Dr Steven Wolinsky, chief of infectious diseases at Northwestern’s Feinberg School of Medicine, said: ‘We now have a path to a cure.
‘The challenge is to deliver drugs at clinically effective concentrations to where the virus continues to replicate within the patient.’
Scroll down for video
HIV can keep growing in the body even when it’s undetectable in the blood of patients after potent antiretroviral drug treatments, scientists revealed. This finding offers new insight into why the virus seems to rapidly bounce back after patients stop taking antiretroviral drugs (file photo)
Potent antiretroviral drugs are able to seemingly get rid of HIV from the bloodstream in most patients.
After the treatment, their blood tests may not detect the virus.
However, HIV is still growing in a viral reservoir within the lymphoid tissue in the body at that time.
And, it ‘quickly rebounds’ in the blood after patients stop taking the drugs.
Scientists concluded that latently infected cells or ongoing low levels of HIV replication maintain those viral reservoirs during antiretroviral treatment.
Scientists long believed that the reservoir only contained long-infected cells in a resting place – instead of newly infected cells.
The study is exciting because it really changes how we think about what is happening in treated patients. It helps explains why some strategies that tried to clear the reservoir have failed
Dr Angela McLean, a professor of mathematical biology at Oxford University
That’s because none of them had seen viruses with new genetic mutations that arise when HIV completes its growth cycles.
Furthermore, most patients don’t develop drug resistant mutations – which would seem likely if HIV was growing in the presence of drugs.
The study analyzed viral sequences in serial samples of lymph node cells.
They also examined blood from three HIV-infected patients.
Each of those patients had no detectable virus in their blood.
The scientists determined that the viral reservoir was constantly replenished by low-level virus replication in the lymphoid tissue.
Infected cells would then move from those ‘protected sanctuaries’ and into the blood, they found.
Therefore, infected cells in drug-sanctuaries within the lymphoid tissue can still produce new viruses.
HOW HIV INFECTS
HIV infects CD4+ T-cells, which play a vital role in the immune system and protect us from diseases. As HIV progresses, it reduces the number of active T-cells in the body until the immune system cannot function correctly, a state known as ‘acquired immune deficiency syndrome’ or AIDS.
Current World Health Organisation guidelines, which the UK government follows, recommend only beginning HIV treatment when the number of T-cells in the bloodstream falls below a certain level.
However, the new model predicts that treatment should start as soon as possible after infection to prevent AIDS from developing in the long term.
The scientists discovered that viral reservoirs were constantly replenished by low-level HIV (pictured) replication in the lymphoid tissue. Infected cells then move from those ‘protected sanctuaries’ into the blood
They can also infect new target cells and replenish the viral reservoir.
That’s why drugs have not been able to completely purge the body of latently infected cells – and kill the virus all together.
AIDS FACTS AND FIGURES
AIDS-related deaths have dropped more than 40 percent since
2004 to 1.2 million a year, the report said.
New HIV infections
have fallen by 35 percent since 2001 to 2 million a year in
Investment in HIV/AIDS surged to almost $22 billion in 2015
from less than $5 billion in 2001.
One of the most remarkable successes has been reducing new
infections among children by 58 percent between 2000 and 2014,
the agency said.
The scientists utilized a mathematical model to track the amount of the virus and number of infected cells as they grew in the sanctuaries – and as they then moved through the body.
The model showed that HIV grows in areas where antiretroviral drug concentrations are lower than in the blood.
The scientists concluded that it is important to deliver high concentrations of antiretroviral drugs to all locations in the body where HIV may grow and evolve.
As such, drugs that penetrate these ‘newly discovered sanctuaries’ will be required to eliminate the viral reservoir – and may bring the medical community closer to finding a cure.
Co-author Dr Angela McLean, a professor of mathematical biology at Oxford University, said: ‘The study is exciting because it really changes how we think about what is happening in treated patients.
‘It helps explains why some strategies that tried to clear the reservoir have failed.’
The study was published in the journal Nature.