Scientific evidence is steadily accumulating:
Scientists have been aware that the so called "elite controllers" — those very few people who are infected with HIV for at least a decade, and yet are able to control viral replication despite the absence of antiretroviral treatment — were always going to be a vital part of future cure research, and are now gaining a better understanding of this unique group of patients.
Some of the more recent science indicates that the elite controller status is related to the host genetics permitting robust cell mediated immunity and/or restricting an infection in their CD4 lymphocytes and macrophages.
Understanding this group of people who efficiently and spontaneously control the virus replication and typically present smaller reservoirs may be key in the search to attaining a "functional" cure that would allow long-term remission of infected individuals.
The Berlin patient
The case of the Berlin patient, Timothy Brown, provided a proof of concept. Timothy Brown, a patient with leukaemia and HIV, received a stem-cell bone-marrow transplant in 2007 from a donor with a gene mutation (CCR5Δ32) which provides natural resistance to HIV, leading to the remission of his leukaemia and he is now considered to be cured of HIV.
Although this approach is too elaborate, risky and specific to serve as a universally applicable HIV cure strategy, the case of the Berlin patient stimulated new interest among the international scientific research community.
Post-treatment controllers – The VISCONTI Cohort and the Mississippi Baby
- VISCONTI Cohort: In France, researchers have identified a unique group of 14 patients, the ANRS VISCONTI cohort, that have been treated very early after infection for a mean duration of three years before stopping their treatment. Since then, they have been able to control their virus replication without the need for ART. Understanding the immune mechanisms involved in these rare post-treatment controllers is of great interest to cure research.
- Mississippi Baby: Early in 2013, researchers led by Deborah Persaud at Johns Hopkins University announced that a Mississippi baby born with HIV was started on antiretroviral treatment about 30 hours after birth. The unidentified child has now been "functionally cured" and has not recieved medication for about a year, with no signs of viral rebound. The case indicates again a correlation between early suppression of HIV to undetectable viral loads and the size of latent HIV reservoirs. The result still needs to be confirmed by further analysis but it further confirms the benefits related to early therapeutic intervention.
Latency reactivation studies: Proof of concept. Current treatments are effective at reducing the levels of the virus in the bloodstream, but a drug which can 'knock out' HIV when it lies dormant is thought to be the key to a cure. Scientists have found that Vorinostat, a drug used to treat lymphoma, can reactivate HIV out of hiding. While other chemicals have disrupted dormant HIV in vitro, this is the first time that any substance has done the same thing in people.
On-going studies provide encouraging results that other molecules in this class of drugs (HDAC inhibitors) may also prove successful in reactivating latent HIV. At this stage, these studies only provide proof of concept that disrupting HIV dormancy is possible, but further investigation is necessary to gain insight into the mechanisms that will follow HIV reactivation. The idea is that the awakened viruses would either kill the cell, or alert the immune system to do the job. Drugs could then stop the new viruses from infecting healthy cells. If all the hidden viruses could be activated, it should be possible to completely drain the reservoir.