HIV drug resistance on HAART despite an undetectable viral load.

HIV is known to have the ability to adapt rapidly its genome under drug pressure, resulting in clinical treatment failure. We present the case of an HIV-infected patient who developed mutations of resistance to nevirapine although he always had an undetectable viral load and without context of inobservance. The concepts of undetectability and virological success in HIV infection must be balanced by the possible appearance of resistance under a treatment considered as effective.