What is HIV?
HIV is a virus that attacks the immune system, which is our body’s natural defence against illness. The virus destroys a type of white blood cell in the immune system called a T-helper cell, and makes copies of itself inside these cells. T-helper cells are also referred to as CD4 cells.
As HIV destroys more CD4 cells and makes more copies of itself, it gradually breaks down a person’s immune system. This means someone living with HIV, who is not receiving treatment, will find it harder and harder to fight off infections and diseases.
If HIV is left untreated, it may take up to 10 or 15 years for the immune system to be so severely damaged it can no longer defend itself at all. However, the speed HIV progresses will vary depending on age, health and background.
Basic facts about HIV
HIV stands for human immunodeficiency virus.
There is effective antiretroviral treatment available so people with HIV can live a normal, healthy life.
The earlier HIV is diagnosed, the sooner treatment can start – leading to better long term health. So regular testing for HIV is important.
HIV is found in semen, blood, vaginal and anal fluids, and breast milk.
HIV cannot be transmitted through sweat, saliva or urine.
Using male condoms or female condoms during sex is the best way to prevent HIV and other sexually transmitted infections.
If you inject drugs, always use a clean needle and syringe, and never share equipment.
If you are pregnant and living with HIV, the virus in your blood could pass into your baby’s body, or after giving birth through breastfeeding. Taking HIV treatment virtually eliminates this risk.
What is AIDS?
AIDS is not a virus but a set of symptoms (or syndrome) caused by the HIV virus. A person is said to have AIDS when their immune system is too weak to fight off infection, and they develop certain defining symptoms and illnesses. This is the last stage of HIV, when the infection is very advanced, and if left untreated will lead to death.
Basic facts about AIDS
AIDS stands for acquired immune deficiency syndrome.
AIDS is also referred to as advanced HIV infection or late-stage HIV.
AIDS is a set of symptoms and illnesses that develop as a result of advanced HIV infection which has destroyed the immune system.
Treatment for HIV means that more people are staying well, with fewer people developing AIDS.
Although there is currently no cure for HIV with the right treatment and support, people with HIV can live long and healthy lives. To do this, it is especially important to take treatment correctly and deal with any possible side-effects.
The breakthrough discovery could explain why – despite monumental advances in suppressing the virus – no treatment has successfully cured anyone of the disease.
“These results are paradigm changing because they demonstrate that cells other than T cells can serve as a reservoir for HIV,” said Dr Jenna Honeycutt, lead-author and postdoctoral research associate in the UNC Division of Infectious Diseases. “The fact that HIV-infected macrophages can persist means that any possible therapeutic intervention to eradicate HIV might have to target two very different types of cells.”
HIV treatments have advanced to the extent that a daily regimen of pills can make the virus undetectable and non transmittable.
Roughly 30 percent of America’s 1.2 million people with HIV have reached an undetectable viral load.
A person with HIV becomes ‘undetectable’ when treatment targeting T-cells suppresses the virus to a level so low in their blood that it cannot be detected by measurements. If a person is undetectable and stays on treatment, they cannot pass HIV on to a partner. No study has ever shown HIV transmission from someone with an undetectable viral load.
To date, an undetectable load is almost always achieved with daily doses of antiretroviral drugs.
But a number of clinical trials – including PRO-140 by CytoDyn, which Charlie Sheen is involved in – hope to be developing treatments that could be administered on a weekly or fortnightly basis.
This endeavor could be transformed by the latest UNC research, which builds on years of speculation in the HIV research community.
Last spring, UNC School of Medicine demonstrated that tissue macrophages supported HIV’s survival in the body, independent of human T cells.
But how macrophages would respond to antiretroviral therapy (ART) was unknown. They also were not sure whether macrophages could be a de facto reservoir for HIV after treatment, or whether they simply supported the virus.
Macrophages are myeloid lineage cells that have been implicated in HIV pathogenesis and in the trafficking of virus into the brain.
Using a humanized myeloid-only mouse (MoM) model devoid of T cells, Garcia and his team showed that ART strongly suppresses HIV replication in tissue macrophages.
Yet when HIV treatment was interrupted, viral rebound was observed in one third of the animals. This is consistent with the establishment of persistent infection in tissue macrophages.
“This is the first report demonstrating that tissue macrophages can be infected and that they respond to antiretroviral therapy,” Honeycutt said.
“In addition, we show that productively infected macrophages can persist despite ART; and most importantly, that they can reinitiate and sustain infection upon therapy interruption even in the absence of T cells – the major target of HIV infection.”
Now that Garcia and his team know HIV persists in macrophages, the next step will be to determine why and how HIV persists in tissue macrophages.
They will also investigate where in the body persistently infected macrophages reside during HIV treatment, and how macrophages respond to therapeutic interventions.