title: HIV co-receptor tropism prediction remains stable over time in treatment-naïve patients.
abstract: HIV co-receptor tropism determination is essential before prescribing the CCR5 antagonist maraviroc. British HIV Association guidelines suggest tropism testing may remain valid for only 90 days in antiretroviral-naïve patients. We aimed to determine the accuracy of this figure. Tropism was assessed in 26 antiretroviral-naïve patients with ongoing viral replication, sampled yearly from first clinic visit. The V3 region of HIV-1 was sequenced in triplicate, then tropism predicted using the Geno2Pheno system. Baseline tropism prediction remained valid for a median of 52 months (range 7-81). For 19/26 individuals baseline tropism remained unchanged throughout a median of 54 months follow-up; 18 R5 tropic and 1 X4 tropic. In seven patients (27%) baseline tropism switched at least once (range 1-4 switches) during follow-up; however, their baseline tropism prediction remained valid for a median of 45 months. Co-receptor tropism in treatment-naïve patients with ongoing viral replication appears highly stable over time, suggesting that baseline genotypic tropism prediction may be valid for a longer duration in patients delaying ART initiation. In this study, baseline tropism prediction remained valid for a median of 52 months, suggesting current guidelines recommending repeat testing after 90 days may be excessively conservative in their assessment of tropism stability.
authors.affiliation: Department of Virology, Royal Free London NHS Foundation Trust, London, UK kejphilip@gmail.com.
authors.forename: Keir Ej
authors.initials: KE
authors.lastname: Philip
authors.affiliation: Department of Virology, Royal Free London NHS Foundation Trust, London, UK.
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Macartney
authors.affiliation: Department of Virology, Royal Free London NHS Foundation Trust, London, UK.
authors.forename: Tim Cr
authors.initials: TC
authors.lastname: Conibear
authors.affiliation: Research Department of Infection and Population Health, University College London, London, UK.
authors.forename: Colette J
authors.initials: CJ
authors.lastname: Smith
authors.affiliation: Department of HIV Medicine, Royal Free London NHS Foundation Trust, London, UK.
authors.forename: Neal
authors.initials: N
authors.lastname: Marshall
authors.affiliation: Department of HIV Medicine, Royal Free London NHS Foundation Trust, London, UK.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Johnson
authors.affiliation: Department of Virology, Royal Free London NHS Foundation Trust, London, UK.
authors.forename: Tanzina
authors.initials: T
authors.lastname: Haque
authors.affiliation: Department of Virology, Royal Free London NHS Foundation Trust, London, UK.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Webster
mesh_terms: D019411:Clinical Laboratory Techniques / Q000379:methods*; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity*; D006801:Humans; D008297:Male; D012367:RNA, Viral / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000379:methods; D056189:Viral Tropism; D014773:Virology / Q000379:methods*
chemical_list: D012367:RNA, Viral
keywords: AIDS; CCR5; HIV; antiretroviral therapy; co-receptor stability; maraviroc; tropism