Drug resistance testing. Researcher preparing the ABI DNA (deoxyribonucleic acid) Analyser for drug resistance testing of samples from PEPFAR (President's Emergency Plan for AIDS Relief) country patients. This instrument makes it possible to analyse the sequencing and fragment characteristics of a uniquely coded DNA molecule. Photographed at the International Lab Branch (ILB) of the Global AIDS Program (GAP), National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP), USA.