The human body can fight off many viruses, but no one has fought off HIV. Why?
After HIV infects a cell, it integrates its genetic material into the cell's DNA
and uses the cell's machinery to replicate itself.
Most HIV infected cells die after a few months,
but a few go into a resting state and survive for years --- even for life.
These latently infected cells are called the HIV reservoir.
This reservoir exists in the blood and other tissues, and poses the greatest obstacle to an HIV cure.
The HIV reservoir is invisible to the body's immune system.
This is because reservoir cells don't display HIV proteins on their surfaces,
so the immune system can't identify and destroy those cells.
Effective HIV treatment, which keeps people healthy,
can block HIV replication,
but it can't eliminate the HIV reservoir.
If a person stops HIV treatment,
virus from the reservoir almost always starts replicating again.
An HIV cure in the classic sense,
meaning it completely removes all HIV from the body,
would need to eradicate the HIV reservoir.
Stem cell transplantation has cured HIV in one person, the Berlin patient.
But the risks, difficulty and expense of such procedures
make this a highly impractical approach for curing HIV in most people.
A different, experimental approach to a classic to cure
would prompt HIV in the reservoir to replicate,
causing infected cells to display HIV proteins.
Then an immune system boost or a drug
would theoretically recognize and kill those cells.
Although numerous methods to activate HIV replication in the reservoir
have been tested over nearly two decades,
no approach has been powerful, safe, or effective enough to succeed yet.
Another experimental approach to a classic cure involves using gene editing
to remove or inactivate the HIV DNA in the chromosomes of latently infected cells.
But concerns about the safety, efficiency, and practicality of this approach
have so far limited its use to laboratory experiments.
Given these challenges, a scientific breakthrough is needed
for these approaches to a classic cure to become feasible.
A more realistic goal than a classic cure is treatment-free remission.
This objective would not involve eradicating the HIV reservoir.
Rather, it would allow a person living with HIV to keep latent virus suppressed without daily medication.
Numerous studies in monkeys and several case reports in people
show that treatment-free remission may be possible.
In the human cases, antiretroviral treatment suppressed HIV soon after infection, and then was halted.
A small number of people continued to control HIV even after treatment stopped.
Scientists are working to understand why this happened
so they can try to induce treatment-free remission in other people.
One approach under investigation involves testing
whether infusions of specific antibodies can induce treatment-free remission.
Monkey studies of this approach yielded encouraging results,
and studies in people are planned or underway.
The National Institute of Allergy and Infectious Diseases
is determined to find a way to help people with HIV
live long and healthy lives without continuous daily medication.
For more information about how we're pursuing this goal, visit our website.