Spectrum of Activity of Raltegravir and Dolutegravir Against Novel Treatment-Associated Mutations in HIV-2 Integrase: A Phenotypic Analysis Using an Expanded Panel of Site-Directed Mutants

Background. Integrase inhibitors (INIs) are a key component of antiretroviral therapy for human immunodeficiency virus-1 (HIV-1) and HIV-2 infection. Although INI resistance pathways are well-defined for HIV-1, mutations that emerge in HIV-2 in response to INIs are incompletely characterized. Methods. We performed systematic searches of GenBank and HIV-2 drug resistance literature to identify treatment-associated mutations for phenotypic evaluation. We then constructed a library of 95 mutants of HIV-2(ROD9 )that contained single or multiple amino acid changes in the integrase protein. Each variant was tested for susceptibility to raltegravir and dolutegravir using a single-cycle indicator cell assay. Results. We observed extensive cross-resistance between raltegravir and dolutegravir in HIV-2(ROD9). HIV-2-specific integrase mutations Q91R, E92A, A153G, and H157Q/S, which have not been previously characterized, significantly increased the half maximum effective concentration (EC50) for raltegravir when introduced into 1 or more mutational backgrounds; mutations E92A/Q, T97A, and G140A/S conferred similar enhancements of dolutegravir resistance. HIV-2(ROD9) variants encoding G118R alone, or insertions of residues SREGK or SREGR at position 231, were resistant to both INIs. Conclusions. Our analysis demonstrates the contributions of novel INI-associated mutations to raltegravir and dolutegravir resistance in HIV-2. These findings should help to improve algorithms for genotypic drug resistance testing in HIV-2-infected individuals.