The introduction of combination anti-retroviral therapy (ART) in 1996 dramatically reduced the severity and high mortality rate associated with HIV infection and yielded the added benefit of reducing mother-to-child transmission during pregnancy. Each “class” of antiretroviral drugs in the cocktail targets a different step of the virus’s replication cycle. So, in much the same manner as defeating an enemy by attacking on multiple fronts, using a combination of anti-HIV drugs proved to be highly effective at blocking HIV from spreading within the body.