Characterization of the Drug Resistance Profiles of Integrase Strand Transfer Inhibitors in Simian Immunodeficiency Virus SIVmac239

Abstract

We previously showed that the simian immunodeficiency virus SIVmac239 is susceptible to human immunodeficiency virus (HIV) integrase (IN) strand transfer inhibitors (INSTIs) and that the same IN drug resistance mutations result in similar phenotypes in both viruses. Now we wished to determine whether tissue culture drug selection studies with SIV would yield the same resistance mutations as in HIV. Tissue culture selection experiments were performed using rhesus macaque peripheral blood mononuclear cells (PBMCs) infected with SIVmac239 viruses in the presence of increasing concentrations of dolutegravir (DTG), elvitegravir (EVG), and raltegravir (RAL). We now show that 22 weeks of selection pressure with DTG yielded a mutation at position R263K in SIV, similar to what has been observed in HIV, and that selections with EVG led to emergence of the E92Q substitution, which is a primary INSTI resistance mutation in HIV associated with EVG treatment failure. To study this at a biochemical level, purified recombinant SIVmac239 wild-type (WT) and E92Q, T97A, G118R, Y143R, Q148R, N155H, R263K, E92Q T97A, E92Q Y143R, R263K H51Y, and G140S Q148R recombinant substitution-containing IN enzymes were produced, and each of the characteristics strand transfer, 3=-processing activity, and INSTI inhibitory constants was assessed in cell-free assays. The results show that the G118R and G140S Q148R substitutions decreased K m = and V max =/K m = for strand transfer compared to those of the WT. RAL and EVG showed reduced activity against both viruses and against enzymes containing Q148R, E92Q Y143R, and G140S Q148R. Both viruses and enzymes containing Q148R and G140S Q148R showed moderate levels of resistance against DTG. This study further confirms that the same mutations associated with drug resistance in HIV display similar profiles in SIV. IMPORTANCEOur goal was to definitively establish whether HIV and simian immunodeficiency virus (SIV) share similar resistance pathways under tissue culture drug selection pressure with integrase strand transfer inhibitors and to test the effect of HIV-1 integrase resistance-associated mutations on SIV integrase catalytic activity and resistance to integrase strand transfer inhibitors. Clinically relevant HIV integrase resistance-associated mutations were selected in SIV in our tissue culture experiments. Not only do we report on the characterization of SIV recombinant integrase enzyme catalytic activities, we also provide the first research anywhere on the effect of mutations within recombinant integrase SIV enzymes on drug resistance.T he limitations of current highly active antiretroviral therapy (HAART) include the incidence of drug resistance observed in patients, issues of drug adherence, and numbers of newly acquired infections. The emergence of drug-resistant viruses can lead to increases in viral load and treatment failure, and such viruses can be transmitted to both healthy individuals as well as to untreated HIV-positive individuals, therefore threatening the long-term effica...

Dolutegravir Monotherapy of Simian Immunodeficiency Virus-Infected Macaques Selects for Several Patterns of Resistance Mutations with Variable Virological Outcomes

“…Notably, both G118R and R263K were found to emerge from HIV sequences in the context of dolutegravir monotherapy (6,13). We previously showed that introducing G118R in SIVmac239 integrase caused an 80% decrease in enzymatic efficiency (22,34). We also confirmed here that the SIV replicative capacity was negatively impaired by introducing the G118R substitution, whereas E92Q was mostly innocuous in this regard (Fig.…”

“…We have reported previously on the effects of E92Q, Q148K, G118R, and R263K on the antiretroviral drug susceptibility of SIV, as these mutations confer low-level (2-to 12-fold) resistance to DTG in vitro (22,29). Here, to explore the importance of viral fitness on treatment failure versus viral suppression, we documented the replicative capacities of wild-type (WT), E92Q mutant, and G118R mutant viruses in monkey peripheral blood mononuclear cells (PBMCs) over 12 days (Fig.…”

“…The same RT quantification assay was used to measure the SIV replicative capacity over time (RT). Infectivity assays were performed as previously described (22). Briefly, TZM-bl reporter cells were infected with serial dilutions of wild-type or mutated SIVmac239, and luciferase production was used to measure infectivity.…”

“…Previous in vitro experiments demonstrated that under increasing DTG concentrations SIVmac239 develops mutations that have also been found for HIV-1 under selection pressure from DTG or other INSTI (22), suggesting the potential relevance of SIV-infected macaques as a model to study DTG resistance in vivo. Accordingly, the current study was designed to study the effects of DTG monotherapy initiated during either acute or chronic SIV infection.…”

Antiviral Activity of Bictegravir and Cabotegravir against Integrase Inhibitor-Resistant SIVmac239 and HIV-1

“…DTG possesses a higher genetic barrier to resistance development in comparison with RAL and EVG, and the latter two drugs share a cross-resistance profile (6-10). Simian immunodeficiency virus (SIV) and HIV-1 share similar resistance profiles against IN-resistance-associated mutations (RAMs) and similar mutational patterns emerge in SIV under drug pressure as for HIV-1 (11)(12)(13)(14).…”