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Abstract
THE HIV-1 PROTEASE L89M SUBSTITUTION CAUSES DRUG RESISTANCE DEPENDING ON THE SUBTYPE PROFILE
A. Calazans1, R.M. Brindeiro1, P.A. Brindeiro1, L.F. Gonzalez1, C. Mortensen2, A. Tanuri1
1Federal University of Rio de Janeiro, Rio de Janeiro, Brasil, 2Applied Biosystems, São Paulo, Brasil
HIV-1 protease mutations rendering resistance to protease inhibitors (PIs) are phenotypically characterized mainly for B subtype viruses. The concern whether these genotypic profiles of PI resistance are suitable for other non-B clade viruses still needs to be addressed. In this work, we describe the effect of HIV-1 protease L89M substitution -recognized as a molecular signature of many non-B HIV-1 subtypes- over the phenotypic EC50 (effective concentration inhibiting 50% viral infectivity) values for each of the six FDA-approved PIs. This Leu to Met polymorphism is the same of its neighbor amino acid (aa.) 90, conferring resistance to Saquinavir (SQV) and Nelfinavir (NFV).
Site-directed mutageneses were performed over plasmid-cloned drug susceptible protease genes of subtype B and F (Bwt and Fwt), to respectively create and reverse the M polymorphism of aa. 89; as well for the creation of L90M mutation. The same panel of 89 and/or 90 mutants was created using cloned protease genes of the two subtypes carrying complex resistance mutation profiles for Ritonavir and Indinavir (named Bmdr and Fmdr). All the constructs were phenotyped in quadruplicates for PI susceptibility by MT-4 cell –MTT based cell viability assay.
L89M mutation conferred 2- and 5-fold increases in EC50 for SQV and NFV respectively, on Fwt 89M90L virus; comparable to the fold resistance values obtained with Bwt 89L90M virus. Surprisingly, Bwt 89M90L clone behaved phenotypically similar to the susceptible Bwt 89L90L virus, while Fwt 89L90M clone presented 3-fold resistance increase higher than its counterpart Bwt 89L90M. For F and B mdr viruses, L89M mutation presented more complex phenotypic results, probably due to interactions with other polymorphisms.
The L89M mutation impacts phenotypic resistance to NFV and SQV differently for F and B clade viruses.
The 2nd IAS Conference on HIV Pathogenesis and Treatment
Abstract no.
807
Suggested Citation
" A. Calazans , et al.
THE HIV-1 PROTEASE L89M SUBSTITUTION CAUSES DRUG RESISTANCE DEPENDING ON THE SUBTYPE PROFILE.
Poster:
The 2nd IAS Conference on HIV Pathogenesis and Treatment:
Abstract no.
807"
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