AEGiS-15IAC: Genotypic resistance assay for entire gp-41 sequence with identification of gp-41 polymorphisms in enfuvirtide-naïve patients and new gp-41 mutations in patients failing enfuvirtide.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

Genotypic resistance assay for entire gp-41 sequence with identification of gp-41 polymorphisms in enfuvirtide-naïve patients and new gp-41 mutations in patients failing enfuvirtide.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. WeOrB1292)

Loutfy MR, Montaner JS, Raboud JM, Saskin R, Smaill F, Rouleau D, Trottier B, Gill J, Schlech W, Gough K, Rachlis A, Cameron B, Lapointe N, Wynhoven B, Mo T, Galli R, Harrigan PR, Walmsley SL
McGill University, Montreal, Quebec, Canada

BACKGROUND: Enfuvirtide is a recently released fusion inhibitor. Resistance testing has generally been limited to 10 gp-41 amino acid (AA) positions. Our objectives were to: 1) Develop a new genotypic resistance assay that assesses the entire gp-41 sequence; 2) Determine polymorphisms in a large untreated cohort and 3) Determine new gp-41 mutations in patients failing enfuvirtide.

METHODS: Following standard viral RNA extraction from plasma, a 1200 bp nested RT-PCR product encompassing almost the entire gp-41 region was generated. The assay was tested on 400 naïve individuals (62 non-B clade) to determine polymorphisms. 44 individuals were assessed before and after enfuvirtide failure to determine novel gp-41 mutations.

RESULTS: Conserved and polymorphic regions of gp-41 were identified in Clade B isolates with 141 of 328 (43.3%) being highly conserved (<1.0% variation) and 75 of 328 codons (22.9%) being partially conserved (1.0%-5.0%), with insertions being common at positions 3 and 215. Natural pol ymorphisms were observed throughout gp-41 in non-B clade viruses ranging from a low of 10 (clade D) to a high of 39 (CRF AE). The assay detected mutations associated with clinically significant enfuvirtide resistance (IAS USA Drug Resistance Group) in 31 of the 44 patients at positions 36D, 38A, 38M, 42T and 43D. Other mutations within the key 10 AA region of unknown significance were selected at 36A, 36V, 38E, 38V, 40H, 40P, 40T, 42D, 43H, 43K, 43S, 44M and 45M in 13 patients. Of 5 patients with no other known mutations, 3 developed a 40H and 45M together. Reversion to wild-type gp-41 was observed as early as 30 days after discontinuing enfuvirtide.

CONCLUSIONS: A new gp-41 genotypic resistance assay assessing the entire AA sequence has been successfully developed. Conserved and polymorphic regions of gp-41 across clades were determined. New gp-41 mutations which are likely clinically relevant were identified.

Keywords: AEGIS, HIV Envelope Protein gp41, Peptide Fragments, Polymorphism, Genetic, Mutation, Membrane Glycoproteins, Genes, pol, RNA, Viral, pentafuside, glycoprotein 41, Humans, immunology, genetics

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