Browsing by Author "Steegen, Kim"

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    Moderate levels of pre-treatment HIV-1 antiretroviral drug resistance detected in the first South African national survey
    (Public Library of Science, 2016) Steegen, Kim; Carmona, Sergio; Bronze, Michelle; Papathanasopoulos, Maria A.; Van Zyl, Gert; Goedhals, Dominique; MacLeod, William; Sanne, Ian; Stevens, Wendy S.
    Background: In order to assess the level of transmitted and/or pre-treatment antiretroviral drug resistance to HIV-1, the World Health Organization (WHO) recommends that regular surveys are conducted. This study’s objective was to assess the frequency of HIV-1 antiretroviral drug resistance in patients initiating antiretroviral treatment (ART) in the public sector throughout South Africa. Methods: A prospective cross-sectional survey was conducted using probability proportional to size sampling. This method ensured that samples from each province were proportionally collected, based on the number of patients receiving ART in each region. Samples were collected between March 2013 and October 2014. Pol sequences were obtained using RT-PCR and Sanger sequencing and submitted to the Stanford Calibrated Population Resistance tool v6.0. Results: A total of 277 sequences were available for analysis. Most participants were female (58.8%) and the median age was 34 years (IQR: 29–42). The median baseline CD4-count was 149 cells/mm3 (IQR: 62–249) and, based on self-reporting, participants had been diagnosed as HIV-positive approximately 44 days prior to sample collection (IQR: 23–179). Subtyping revealed that 98.2% were infected with HIV-1 subtype C. Overall, 25 out of 277 patients presented with ≥1 surveillance drug resistance mutation (SDRM, 9.0%, 95% CI: 6.1–13.0%). Non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations were the most numerous mutations detected (n = 23). Only two patients presented with a protease inhibitor (PI) mutation. In four patients ≥4 SDRMs were detected, which might indicate that these patients were not truly ART-naïve or were infected with a multi-resistant virus. Conclusions: These results show that the level of antiretroviral drug resistance in ART-naïve South Africans has reached moderate levels, as per the WHO classification. Therefore, regular surveys of pre-treatment drug resistance levels in all regions of South Africa is highly recommended to monitor the changing levels of pre-treatment antiretroviral drug resistance.
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    Mutational correlates of virological failure in individuals receiving a WHO-recommended tenofovir-containing first-line regimen : an international collaboration
    (Elsevier, 2017) Rhee, Soo-Yon; Varghese, Vici; Holmes, Susan P.; Van Zyl, Gert U.; Steegen, Kim; Boyd, Mark A.; Cooper, David A.; Nsanzimana, Sabin; Saravanan, Shanmugam; Charpentier, Charlotte; De Oliveira, Tulio; Etiebet, Mary-Ann A.; Garcia, Federico; Goedhals, Dominique; Gomes, Perpetua; Gunthard, Huldrych F.; Hamers, Raph L.; Hoffmann, Christopher J.; Hunt, Gillian; Jiamsakul, Awachana; Kaleebu, Pontiano; Kanki, Phyllis; Kantor, Rami; Kerschberger, Bernhard; Marconi, Vincent C.; Ndahimana, Jean D'amour; Ndembi, Nicaise; Ngo-Giang-Huong, Nicole; Rokx, Casper; Santoro, Maria M.; Schapiro, Jonathan M.; Schmidt, Daniel; Seu, Lillian; Sigaloff, Kim C. E.; Sirivichayakul, Sunee; Skhosana, Lindiwe; Sunpath, Henry; Tang, Michele; Yang, Chunfu; Carmona, Sergio; Gupta, Ravindra K.; Shafer, Robert W.
    Tenofovir disoproxil fumarate (TDF) genotypic resistance defined by K65R/N and/or K70E/Q/G occurs in 20% to 60% of individuals with virological failure (VF) on a WHO-recommended TDF-containing first-line regimen. However, the full spectrum of reverse transcriptase (RT) mutations selected in individuals with VF on such a regimen is not known. To identify TDF regimen-associated mutations (TRAMs), we compared the proportion of each RT mutation in 2873 individuals with VF on a WHO-recommended first-line TDF-containing regimen to its proportion in a cohort of 50,803 antiretroviral-naïve individuals. To identify TRAMs specifically associated with TDF-selection pressure, we compared the proportion of each TRAM to its proportion in a cohort of 5805 individuals with VF on a first-line thymidine analog-containing regimen. We identified 83 TRAMs including 33 NRTI-associated, 40 NNRTI-associated, and 10 uncommon mutations of uncertain provenance. Of the 33 NRTI-associated TRAMs, 12 – A62V, K65R/N, S68G/N/D, K70E/Q/T, L74I, V75L, and Y115F – were more common among individuals receiving a first-line TDF-containing compared to a first-line thymidine analog-containing regimen. These 12 TDF-selected TRAMs will be important for monitoring TDF-associated transmitted drug-resistance and for determining the extent of reduced TDF susceptibility in individuals with VF on a TDF-containing regimen.
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    PhyloPi: An affordable, purpose built phylogenetic pipeline for the HIV drug resistance testing facility
    (Public Library of Science, 2019-03-05) Bester, Phillip Armand; De Vries, Andrie; Riekert, Stephanus; Steegen, Kim; van Zyl, Gert; Goedhals, Dominique
    Introduction: Phylogenetic analysis plays a crucial role in quality control in the HIV drug resistance testing laboratory. If previous patient sequence data is available sample swaps can be detected and investigated. As Antiretroviral treatment coverage is increasing in many developing countries, so is the need for HIV drug resistance testing. In countries with multiple languages, transcription errors are easily made with patient identifiers. Here a self-contained blastn integrated phylogenetic pipeline can be especially useful. Even though our pipeline can run on any unix based system, a Raspberry Pi 3 is used here as a very affordable and integrated solution. Performance benchmarks: The computational capability of this single board computer is demonstrated as well as the utility thereof in the HIV drug resistance laboratory. Benchmarking analysis against a large public database shows excellent time performance with minimal user intervention. This pipeline also contains utilities to find previous sequences as well as phylogenetic analysis and a graphical sequence mapping utility against the pol area of the HIV HXB2 reference genome. Sequence data from the Los Alamos HIV database was analyzed for inter- and intra-patient diversity and logistic regression was conducted on the calculated genetic distances. These findings show that allowable clustering and genetic distance between viral sequences from different patients is very dependent on subtype as well as the area of the viral genome being analyzed. Availability: The Raspberry Pi image for PhyloPi, source code of the pipeline, sequence data, bash-, python- and R-scripts for the logistic regression, benchmarking as well as helper scripts are available at http://scholar.ufs.ac.za:8080/xmlui/handle/11660/7638 and https://github.com/ArmandBester/phylopi. The PhyloPi image and the source code are published under the GPLv3 license. A demo version of the PhyloPi pipeline is available at http://phylopi.hpc.ufs.ac.za/.