HIV type-1 drug resistance in antiretroviral treatment-naive adults infected with non-B subtype virus in the United Kingdom.

BACKGROUND

There is an increasing prevalence of non-B subtype HIV type-1 (HIV-1) infections in Europe, reflecting patterns of migration. We examined the characteristics of HIV-1 drug resistance in antiretroviral treatment (ART)-naive individuals migrating to the UK.

METHODS

Resistance tests reported to the UK HIV Drug Resistance Database between 2001 and 2006 were included. Demographic data were obtained via linkage to national databases. Resistance was defined as ≥ 1 drug resistance mutation. Non-B HIV-1 subtype was used as a surrogate marker of infection acquired outside the UK. Logistic regression was used to examine the association between demographics and the prevalence of resistance.

RESULTS

Overall, 196/4,291 (4.6%) samples with non-B subtype showed resistance compared with 745/6,435 (11.6%) samples for subtype B. Among non-B subtypes, the prevalence of resistance decreased over time (6.0% in 2001-2003 to 3.2% in 2006) and was independently associated with later calendar year of sampling (P=0.001). Resistance was confined mainly to one ART class (85%); non-nucleoside reverse transcriptase inhibitor resistance was more common in subtype C (47%) compared with non-B non-C subtypes (29%; P=0.02). M184V was more common in non-B subtypes (non-B 30% versus B 5%; P<0.001) and T215 variants were more common in subtype B (non-B 10% versus B 49%; P<0.001).

CONCLUSIONS

In ART-naive individuals living in the UK, but who are likely to have acquired HIV-1 abroad, we observed a downward trend in resistance over time, which is surprising in light of ART roll-out in resource-limited settings. Reassuringly, resistance was mainly confined to one drug class; however, patterns of resistance differed by subtype, with some evidence of possible undisclosed prior therapy in non-B subtypes.