Polymorphisms of HIV-2 integrase and selection of resistance to raltegravir.
BACKGROUND
Human Immunodeficiency Virus type 2 is naturally resistant to some antiretroviral drugs, restricting therapeutic options for patients infected with HIV-2. Regimens including integrase inhibitors (INI) seem to be effective, but little data on HIV-2 integrase (IN) polymorphisms and resistance pathways are available.


METHODS
The integrase coding sequence from 45 HIV-2-infected, INI-naïve, patients was sequenced and aligned against the ROD (group A) or EHO (group B) reference strains and polymorphic or conserved positions were analyzed.To select for raltegravir (RAL)-resistant variants in vitro, the ROD strain was cultured under increasing sub-optimal RAL concentrations for successive rounds. The phenotype of the selected variants was assessed using an MTT assay.


RESULTS
We describe integrase gene polymorphisms in HIV-2 clinical isolates from 45 patients. Sixty-seven percent of the integrase residues were conserved. The HHCC Zinc coordination motif, the catalytic triad DDE motif, and AA involved in IN-DNA binding and correct positioning were highly conserved and unchanged with respect to HIV-1 whereas the connecting residues of the N-terminal domain, the dimer interface and C-terminal LEDGF binding domain were highly conserved but differed from HIV-1. The N155 H INI resistance-associated mutation (RAM) was detected in the virus population from one ARV-treated, INI-naïve patient, and the 72I and 201I polymorphisms were detected in samples from 36 and 38 patients respectively. No other known INI RAM was detected.Under RAL selective pressure in vitro, a ROD variant carrying the Q91R+I175M mutations was selected. The Q91R and I175M mutations emerged simultaneously and conferred phenotypic resistance (13-fold increase in IC50). The Q91R+I175M combination was absent from all clinical isolates. Three-dimensional modeling indicated that residue 91 lies on the enzyme surface, at the entry of a pocket containing the DDE catalytic triad and that adding a positive charge (Gln to Arg) might compromise IN-RAL affinity.


CONCLUSIONS
HIV-2 polymorphisms from 45 INI-naïve patients are described. Conserved regions as well as frequencies of HIV-2 IN polymorphisms were comparable to HIV-1. Two new mutations (Q91R and I175M) that conferred high resistance to RAL were selected in vitro, which might affect therapeutic outcome.
Laboratoire de Rétrovirologie, CRP-Santé, Luxembourg, Luxembourg.
Danielle Perez
DP
Bercoff
Perrine
P
Triqueneaux
Christine
C
Lambert
Aboubacar Alassane
AA
Oumar
Anne-Marie
AM
Ternes
Sounkalo
S
Dao
Patrick
P
Goubau
Jean-Claude
JC
Schmit
Jean
J
Ruelle
D019380:Anti-HIV Agents / Q000494:pharmacology*; D002460:Cell Line; D024882:Drug Resistance, Viral; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology*; D019427:HIV Integrase / Q000235:genetics* / Q000378:metabolism; D015498:HIV-2 / Q000145:classification / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D011760:Pyrrolidinones / Q000494:pharmacology*; D000068898:Raltegravir Potassium
D019380:Anti-HIV Agents; D011760:Pyrrolidinones; D000068898:Raltegravir Potassium; D019427:HIV Integrase; C514802:p31 integrase protein, Human immunodeficiency virus 2