In vitro analysis of the replicative capacity and phenotypic susceptibility to integrase inhibitors of HIV-2 mutants with integrase insertions

Background HIV-2 resistance to integrase strand-transfer inhibitors (INSTIs) is characterized by two main pathways: (i) mutations at codons 143, 148 and155; and (ii) amino acid insertion after integrase codon 231 (231ins). Objectives To complete INSTI resistance data on HIV-2 by determining the viral replicative capacity and INSTI phenotypic susceptibility of integrase mutants obtained through site-directed mutagenesis. Methods Site-directed mutants (SDMs) were constructed and viral stocks produced. Viral replicative capacity was assessed by measuring HIV-2 viral load at days 3, 7 and 14. In vitro phenotypic susceptibility was measured using the ANRS PBMC assay. Results Viruses bearing 231ins did not present impaired replicative capacity, except the 231ins GIRGK mutant. A 231ins GK SDM was resistant to raltegravir and cabotegravir, but remained susceptible to dolutegravir and bictegravir. SDMs harbouring a 5 amino acid insertion (GYKGK or SREGK) were both resistant to all INSTIs. The SDM with T97A+N155H, with or without E92Q, was resistant to all INSTIs, except bictegravir. Conclusions These first data on the newly described resistance pathway 231ins, using site-directed mutagenesis, showed no measurable impact on viral fitness and confirmed the decreased susceptibility to a first-generation INSTI (raltegravir) and cabotegravir. Resistance to second-generation INSTIs (dolutegravir and bictegravir) occurred for mutants with a 5 amino acid 231ins.

Automated summary

HIV-2 resistance to INSTIs can occur through mutations or amino acid insertions. The newly described resistance pathway 231ins does not significantly affect viral replicative capacity, except for the 231ins GIRGK mutant. Mutants with a 5 amino acid insertion (GYKGK or SREGK) are resistant to all INSTIs.