HIV-1 group O resistance pathway with raltegravir is similar to HIV-1 group M

Virological response to integrase strand transfer inhibitor-based antiretroviral combinations in HIV-1 group O-infected patients

: Although integrase strand transfer inhibitors (INSTIs) are widely used in HIV-1 group M (HIV-1/M) infections, little is known about their efficacy against genetically divergent HIV-1 group O (HIV-1/O) strains. Previous phenotypic works have demonstrated the variable susceptibility of HIV-1/O strains, depending on INSTI drugs. Clinical data are very limited and obtained from a few patients.

OBJECTIVES

To investigate the virological success rate of an INSTI-based combination of antiretroviral therapy (cART) in a large population of HIV-1/O-infected patients, and to describe resistance-associated mutations (RAM) at virological failure.

METHODS

The virological response of 39 patients receiving INSTI-based cART during their follow-up was analysed i) at the last point of the first INSTI initiation and ii) at their most recent visit. RAM analysis was performed at virological failures. Resistance interpretation was based on the French National Agency of Research on AIDS and viral hepatitis (ANRS) rules.

RESULTS

Virological success at both time points of analysis was high, with more than 87% of the patients with undetectable plasma viral load. Among the six patients with virological failure, three selected RAM described for HIV-1/M resistance, and two had already RAM, before INSTI initiation.

CONCLUSION

Our results show that HIV-1/O infected patients receiving INSTI-based cART presented a high rate of virological success whatever their previous lines; we have also shown that resistance rules for HIV-1/M could be considered when failure occurs. These data are of importance especially in the context of WHO recommendations for a wider use of this class.

HIV-1 Group O Genotypes and Phenotypes: Relationship to Fitness and Susceptibility to Antiretroviral Drugs

Despite only 30,000 group O HIV-1 infections, a similar genetic diversity is observed among the O subgroups H (head) and T (tail) (previously described as subtypes A, B) as in the 9 group M subtypes (A-K). Group O isolates bearing a cysteine at reverse transcriptase (RT) position 181, predominantly the H strains are intrinsically resistant to non-nucleoside reverse transcriptase inhibitors (NNRTIs). However, their susceptibility to newer antiretroviral drugs such as etravirine, maraviroc, raltegravir (RAL), and elvitegravir (EVG) remains relatively unknown. We tested a large collection of HIV-1 group O strains for their susceptibility to four classes of antiretroviral drugs namely nucleoside RT, non-nucleoside RT, integrase, and entry inhibitors knowing in advance the intrinsic resistance to NNRTIs. Drug target regions were sequenced to determine various polymorphisms and were phylogenetically analyzed. Replication kinetics and fitness assays were performed in U87-CD4(+)CCR5 and CXCR4 cells and peripheral blood mononuclear cells. With all antiretroviral drugs, group O HIV-1 showed higher variability in IC50 values than group M HIV-1. The mean IC50 values for entry and nucleoside reverse transcriptase inhibitor (NRTI) were similar for group O and M HIV-1 isolates. Despite similar susceptibility to maraviroc, the various phenotypic algorithms failed to predict CXCR4 usage based on the V3 Env sequences of group O HIV-1 isolates. Decreased sensitivity of group O HIV-1 to integrase or NNRTIs had no relation to replicative fitness. Group O HIV-1 isolates were 10-fold less sensitive to EVG inhibition than group M HIV-1. These findings suggest that in regions where HIV-1 group O is endemic, first line treatment regimens combining two NRTIs with RAL may provide more sustained virologic responses than the standard regimens involving an NNRTI or protease inhibitors.