HIV DRUG resistance genotyping – an Australian perspective of its role and utilisation in contemporary HIV practice

Abstract

Resistance to individual drugs within combination antiretroviral therapies (cART) regimens has been a growing international problem. HIV drug-resistance genotyping has been widely, but not universally, available in Australia for over a decade, initially through state funded reference laboratories, and more recently since 2011 by Medicare through the Pathology Services Table. An assessment by the Medical Services Advisory Committee (MSAC) found both in-house and commercial kit testing to be cost effective in a complex modelling of outcomes. Currently standard resistance genotyping provides a predicted resistance profile for three classes of antiretroviral agents. Individual state-based service data show moderate prevalence of primary resistance to at least one antiretroviral agent from the three main classes of NRTI, NNRTI and PI. Non RTI and non-PI therapies are increasingly being used with little evidence of primary resistance. Laboratories will need to develop a broader repertoire of gene sequencing capability to accommodate the clinical need in those exposed to these newer drugs. CCR5 blockers require pre-use tropism testing of an individual’s virus. The early reported experience of laboratories performing tropism genotyping from integrated proviral DNA sequences in virally suppressed patients highlights the need for caution in interpreting tropism in the setting of viral suppression.