HIV and its treatment

HIV disease progression occurs when the virus replicates and infects new cells. HIV primarily targets CD4 T-cells, which direct the body’s immune response. As HIV infects and kills more CD4 cells, the body is less able to defend itself against viruses, bacteria, and other pathogens. This process is discussed in more detail in the section How the immune system works.

Disrupting HIV replication prevents the virus from infecting new cells and allows for CD4 cell recovery. The virus has a complex life-cycle that involves entering a cell, inserting and copying viral genetic material, producing new viral proteins, and assembling these proteins into new viral particles (virions) that can go on to infect other cells.

Because the HIV life-cycle has so many steps, drugs can disrupt the virus in many different ways. The most effective regimens combine drugs from different classes, thereby attacking HIV from multiple angles. Doing so reduces the ability of the virus to develop drug resistance.

While highly active antiretroviral therapy (HAART) regimens can dramatically reduce HIV replication, some antiretroviral drugs interfere with the normal workings of human cells, causing a variety of side-effects. Fortunately, the past few years has seen the development of drugs in new drug classes and 'second-generation' drugs that can be used in regimens that provide potent and durable results with fewer toxic side-effects and easier dosing schedules.