Published in: JAIDS: Journal of Acquired Immune Deficiency Syndromes (2004) Status: Postprint (Author’s version) Current Levels of Drug Resistance Among Therapy-Naive HIV-infected Patients Have Significant Impact on Treatment Response

Resistant HIV can be transmitted from one patient to another.1 Recent large-scale European research found one-tenth of viruses from untreated patients showing at least 1 resistance-related mutation.2 Such investigations are mainly driven by the concern that resistant virus could at some point hamper optimal treatment response. However, the impact of baseline drug resistance on treatment response is not well studied. Various genotypic interpretation methods are used to assess resistance in drug-naive patients. When transmitted resistance is the topic of interest, irrespective of treatment, primary mutations are considered most indicative. Secondary mutations could also be the result of natural variation. However, when interpreting resistance in view of the response to the installed treatment, all positions possibly contributing to the selective advantage of the virus in the presence of drug should be taken into account. In this study protocol we wanted to document transmitted drug resistance among recently diagnosed therapy-naive HIV-infected patients whose disease was diagnosed in 2000 in Belgium and to study therapy response considering transmitted drug resistance but also scoring the genotype according to interpretation algorithms for therapy response. Samples from therapy-naive patients whose disease was diagnosed in 2000 were collected retrospectivel