Treatment

HIV binds to CD4 cell surface molecules, entry into the cell also requires binding to co-receptorsCXCR4 and CCR5). This step can be inhibited by fusion/entry inhibitors.
HIV is uncoated inside the cell and reverse transcriptase copies genomic RNA into DNA, making errors at a frequence of about one per replication cycle. Reverse transcriptase inhibitors were the first class of HIV inhibitors to be used as drugs.
Viral DNA can integrate into DNA and become a part of the cellular genome. This step makes the infection irreversible, and may mean that eliminating the virus from an infected individual is not possible. Integrase inhibitors are designed to block this step of infection.
The virus uses cellular machinery to synthesize viral proteins. Several of these are long amino acid chains which must be cleaved by a specific viral protease before new viral particles can become active. Protease inhibitors block viral maturation at this step.
New drugs are rapidly being developed

The drugs interfer with HIV replication at multiple steps as indicated above (integrase inhibitors in developmental stages only). HAART or highly active anti-retroviral therapy with a combination of drugs results in a dramatic reduction in viral levels. HAART coupled with improved treatments of HIV caused secondary infections has dramatically improved survival for HIV infected patients.
Deaths in the United States.
Image courtesy of HIV Insight, Nature 410,966 (01). Used with permission.
HAART increases survival, but does not eliminate the virus. CD4+ T cells maturing in the thymus can be infected and harbor virus indefinately. Virus levels rise rapidly if HAART is discontinued.
Immune function is significantly restored in treated individuals. However, the drug regime is difficult and accompanied by complications that may prevent continued treatments.
RNA viruses rapidly mutate. 10 billion HIV-1 virions are generated daily, with a rate giving one mutation for each new genome of 9,2000 nucleotides per replication cycle. Genomes with every possible mutation and many double mutations are generated daily. The rapidly changing virus makes therapy difficult.
Resistant virus emerges at high frequency.
Therapy is very expensive, and cannot be afforded by most countries with significant numbers of HIV infected people. Providing affordable drugs throughout the world remains a difficult goal for world health.
3 by 5; an international effort to increase the availability of antiretroviral drugs, with a goal of treating 3 million HIV infected people by 2005