Selection of T1249-Resistant Human Immunodeficiency Virus Type 1 Variants

Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Center of the University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands.
Journal of Virology (Impact Factor: 4.44). 08/2008; 82(13):6678-88. DOI: 10.1128/JVI.00352-08
Source: PubMed


Human immunodeficiency virus type 1 (HIV-1) entry is an attractive target for therapeutic intervention. Two drugs that inhibit this process have been approved: the fusion inhibitor T20 (enfuvirtide [Fuzeon]) and, more recently, the CCR5 blocker maraviroc (Selzentry). T1249 is a second-generation fusion inhibitor with improved antiviral potency compared to the first-generation peptide T20. We selected T1249-resistant HIV-1 variants in vitro by serial virus passage in the presence of increasing T1249 doses after passage with wild-type and T20-resistant variants. Sequence analysis revealed the acquisition of substitutions within the HR1 region of the gp41 ectodomain. The virus acquired mutations of residue V38 to either E or R in 10 of 19 cultures. Both E and R at position 38 were confirmed to cause resistance to T1249, as well as cross-resistance to T20 and C34, but not to the third-generation fusion inhibitor T2635. We also observed substitutions at residues 79 and 90 (Q79E and K90E), which provide modest resistance to T1249 and, interestingly, T2635. Thus, the gp41 amino acid position implicated in T20 resistance (V38 replaced by A, G, or W) is also responsible for T1249 resistance (V38 replaced by E, R, or K). These results indicate that T20 and T1249 exhibit very similar inhibition modes that call for similar but not identical resistance mutations. All T1249-resistant viruses with changes at position 38 are cross resistant to T20, but not vice versa. Furthermore, substitutions at position 38 do not provide resistance to the third-generation inhibitor T2635, while substitution at positions 79 and 90 do, suggesting different resistance mechanisms.

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    • "The V38A single mutant remaining susceptible to RC-101 provides evidence that RC-101 targets a region outside of the ENF binding site. This finding is particularly promising since RC-101, and similarly acting θ-defensins, would likely remain active against HIV-1 harboring other ENF-resistance mutations such as those frequently observed in the “GIV” region of HR1 [29], [30]. "
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    • "Clinical application of T-20 has shown that it can quickly induce mutations in the GIV motif (residues 547–556) in the viral gp41 NHR domain, resulting in high resistance [29]. Since T-1249 and other PBD-containing C-peptides also contain the GIV motif-binding domain, they are less susceptible to T-20-resistant HIV-1 strains [30]. To overcome this problem, we designed two peptides, CP32 and CP32M, which contain only the PBD, but no motif-binding domain. "
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    • "Since both T20 and C34 peptides have an overlapping sequence in CHR domain,viruses with mutations in the GIV motif (residues 36–44) in the N-terminal region of the NHR domain are rendered highly resistant to T20 [25] [26] [27] [28] [29] [30] and partially resistant to C34 [31]. It has been widely believed that T20 and C34 share a common target, i.e., inhibition of HIV fusion with the target cell membrane by binding to the viral NHR domain to block the fusion core formation. "
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