Evolution of raltegravir resistance during therapy.

Objectives We investigated the prevalence of raltegravir resistance-associated mutations at baseline and their evolution during raltegravir therapy in patients infected with different HIV-1 subtypes. Methods At pre-treatment screening, the integrase gene from plasma samples from patients infected with subtype B and non-B viruses was analysed. Raltegravir resistance evolution was further evaluated in 10 heavily pre-treated patients. Results Two hundred and nine plasma samples from 94 subtype B and 115 non-B patients were sequenced. No signature/primary raltegravir resistance mutations were detected at baseline. The secondary mutations L74M, T97A, V151I and G163R were observed with a frequency of Conclusions A number of secondary and additional mutations were found in baseline genotypes. During therapy, when the virus was not optimally suppressed, resistance mutations developed, which were dependent on subtype and time on raltegravir. [ABSTRACT FROM AUTHOR]