What is HIV drug resistance?

HIV replication is error-prone due to the absence of an effective proofreading mechanism. This gives rise to a high number of mutations, most of which will result in the production of non-functional proteins. However, some mutations will emerge in the viral proteins targeted by antiretroviral agents resulting in HIV drug resistance.

Resistance-conferring mutations are classified according to the class of antiretroviral drug to which they confer a reduced sensitivity. The classes of antiretroviral drugs currently include: nucleoside/nucleotide reverse transcriptase inhibitors (NRTI); non-nucleoside reverse transcriptase inhibitors (NNRTI); protease inhibitors; entry/fusion inhibitors and integrase inhibitors. 

The systematic collation of HIV drug resistance data from drug-naïve individuals is vital to understanding the epidemiology of transmitted drug resistance (TDR), whilst data from those already receiving antiretroviral drugs provides indirect evidence of the contribution drug resistance makes to virological failure. These data are therefore extremely important for healthcare providers. 

The number of resistance tests being carried out has increased as a result of the British HIV Association guidelines recommending routine pre-therapy testing. The findings of the Database of significant levels of TDR in the UK were instrumental in this recommendation being adopted. 

For more information on HIV drug resistance go the Useful links page.