Background: Surveillance for transmitted HIV-1 drug resistance was conducted among drug-naive HIV-1-infected pregnant women in South Africa, where single-dose nevirapine has been in use since 2001 and a national antiretroviral treatment programme started in 2004.
Methods: All subjects were from the Gauteng Province and were part of the 2002 and 2004 annual antenatal HIV seroprevalence survey conducted by the South African National Department of Health. All subjects met the inclusion criteria as set out by the World Health Organisation guidelines for HIV-1 transmitted drug resistance surveillance (women <22 years of age and in first pregnancy). Genotyping was performed on viral RNA by sequencing the protease and reverse transcriptase genes. Samples were also tested for the K103N mutation using a highly sensitive allele-specific real-time PCR assay (AS-PCR).
Results: Of 128 eligible participants from 2002, 65 (51%) samples were successfully amplified. None of them had evidence of resistance mutations by genotyping or by AS-PCR. Of 117 eligible participants from 2004, 48 (41%) samples were successfully amplified. Of these, one had T69D and one had the K70R resistance mutation, to give a total of 2/48 (4.2%) participants with evidence of resistance mutations by genotyping. One sample that was wild-type by genotyping was positive for K103N by AS-PCR. All samples clustered phylogenetically with HIV-1 subtype C, the predominant subtype circulating in South Africa.
Conclusions: Using the threshold survey, resistance prevalence overall and for each drug class in 2002 and 2004 was <5% for the Gauteng province of South Africa. The detection of a low frequency of resistance mutations in the 2004 survey suggests that surveillance should be conducted annually among untreated populations to determine if this increases with time.