Antiretroviral Therapy: How HIV Treatment Works Today

Antiretroviral therapy (ART) is the combination of at least three anti-HIV drugs that attack different steps of the virus's life cycle at once: blocking reverse transcriptase, blocking integrase, or blocking the protease that assembles new virus particles. HIV cannot be cured yet because it hides its DNA inside human chromosomes, but ART shuts down replication so completely that the virus becomes undetectable in the blood and the immune system recovers.

This matters because ART turned HIV from a fatal disease into a manageable chronic condition. A person who starts treatment early and takes it daily now has a near-normal life expectancy, and large studies have proven that an undetectable viral load means the virus cannot be transmitted sexually, summed up as U=U (undetectable equals untransmittable).

Key Concepts

• HIV life cycle targets: reverse transcriptase (copies viral RNA into DNA), integrase (inserts that DNA into the human genome), protease (cuts viral proteins into working parts).
• Drug classes: NRTIs (nucleoside reverse transcriptase inhibitors), NNRTIs, INSTIs (integrase strand transfer inhibitors), protease inhibitors, and entry inhibitors.
• First-line regimen (WHO): tenofovir plus lamivudine plus dolutegravir (TLD), taken as a single daily tablet; dolutegravir is an INSTI with a high barrier to resistance.
• CD4 count: the number of helper T cells per microlitre; below 200 marks severe immunodeficiency where opportunistic infections strike.
• Viral load: copies of HIV RNA per mL of blood; below 50 copies per mL counts as suppressed.
• Adherence: at least 95 percent of doses must be taken on time to keep the virus suppressed.

How It Works

1. HIV enters a CD4 T cell and reverse transcriptase converts its RNA into DNA; NRTIs and NNRTIs block this step.
2. Integrase splices the viral DNA into the cell's chromosomes; INSTIs like dolutegravir block this step.
3. The cell manufactures long viral protein chains; protease inhibitors stop them being cut into functional pieces.
4. Blood viral load falls below detection within about 6 months, and CD4 counts climb by roughly 50 to 150 cells per microlitre in the first year.

Worked Example

A newly diagnosed patient has a viral load of 100,000 copies per mL and starts TLD. Step 1: convert to log scale; log10 of 100,000 = 5.0. Step 2: after 6 months of perfect adherence, the viral load is 40 copies per mL; log10 of 40 is about 1.6. Step 3: the drop is 5.0 minus 1.6 = 3.4 logs, far beyond the 1-log drop at 8 weeks that guidelines call an adequate early response. If instead the viral load had stayed above 1,000 copies per mL, that would signal treatment failure, prompting adherence counselling and resistance testing before any regimen change.

Common Misconceptions

• "ART cures HIV, so I can stop when tests go negative." ART only suppresses replication; the hidden proviral DNA remains, and stopping lets the virus rebound within weeks.
• "Undetectable means I can take treatment breaks." Breaks breed resistance; suppression must be continuous, which is why adherence above 95 percent is the single biggest predictor of success.
• "One strong pill is enough."

Real-World Applications

• Lifelong treatment of all people living with HIV, started as soon as diagnosed regardless of CD4 count.
• Post-exposure prophylaxis: TLD for 28 days started within 72 hours of a needlestick or sexual exposure.
• Pre-exposure prophylaxis: daily tenofovir plus emtricitabine for people at high risk.
• Prevention of mother-to-child transmission: ART through pregnancy and breastfeeding keeps transmission below 2 percent.

Antiretroviral therapy combines three drugs hitting three different viral enzymes, driving the viral load below 50 copies per mL and letting CD4 cells recover. It does not cure, it must never be interrupted, and adherence above 95 percent is everything.