Achillion Pharmaceuticals is looking for the Achilles heel of infectious disease. The firm is developing treatments for infectious diseases, including antiviral treatments for HIV infection and hepatitis C, as well as antibacterials for fighting drug-resistant hospital-based infections. Lead candidate elvucitabine is in late-stage clinical trials for the treatment of HIV; the drug is designed specifically for patients who have become resistant to existing antiviral drugs. Achillion is also focused on the development of three hepatitis C treatments (one of which it is developing in collaboration with biotech firm Gilead Sciences). Another candidate is aimed at combating staph and other drug-resistant infections.