TitleLow rates of nucleoside reverse transcriptase inhibitor resistance in a well-monitored cohort in South Africa on antiretroviral therapy
AuthorsCarole L Wallis, Maria A Papathanasopolous, Matthew Fox, Francesca Conradie, Prudence Ive, Catherine Orrell, Jennifer Zeinecker, Ian Sanne, Robin Wood, James McIntyre, Wendy Stevens, the CIPRA-SA project 1 study team
PublicationAntiviral Therapy. 2011 Nov; 17:313-320.


The emergence of complex HIV-1 drug resistance mutations has been linked to the duration of time patients are on a failing antiretroviral drug regi- men. This study reports on resistance profiles in a closely monitored subtype C infected cohort.


A total of 812 participants were enrolled into the CIPRA-SA ‘safeguard the household’ study, viral loads were determined at 12-weekly intervals for 96 weeks. Virological failure was defined as either a <1.5 log decrease in viral load at week 12 or two consecutive viral load measurements of >1,000 RNA copies/ml after week 24. Regimens prescribed were in line with the South Afri- can roll-out programme (stavudine, lamivudine, efavirenz or nevirapine). Viral RNA was extracted from patients with virological failure, and pol reverse-transcriptase PCR and sequence analysis were performed to determine drug-resistant mutations.


Virological failure was observed in 83 participants on the first-line regimen during the study period, of which 61 (73%) had HIV-1 drug-resistant mutations. The M184V mutation was the most frequent (n=46; 65%), followed by K103N (46%) and Y181C (21%). Thymidine analogue mutations were infrequent (1%) and Q151M was not observed.


Drug resistance profiles were less complex than has been previously reported in South Africa using the same antiretroviral drug regimens. These data sug- gest that frequent viral load monitoring limits the level and complexity of resistance observed in HIV-1 subtype C, preserving susceptibility to second-line options.