Gert van Zyl

Prof. Gert van Zyl

orcid

Research Focus & Metrics

Academic Career Length

27Years (2000-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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9 March 2021 in Nature
Verified
Journal Article
Closed access
PDF file
HTHouriiyah Tegally
Houriiyah Tegally
EWEduan Wilkinson
Eduan Wilkinson
Marta GiovanettiMarta Giovanetti
Marta Giovanetti
AIArash Iranzadeh
Arash Iranzadeh
Vagner FonsecaVagner Fonseca
Vagner Fonseca
TOTulio De Oliveira
Tulio De Oliveira

1 April 2011 in Infectious Disorders - Drug Targets
Verified
Journal Article
Closed access
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JNJean B. Nachega
Jean B. Nachega
VMVincent C Marconi
Vincent C Marconi
GZGert van Zyl
Gert van Zyl
EGEdward M. Gardner
Edward M. Gardner
Wolfgang PreiserWolfgang Preiser
Wolfgang Preiser
RGRobert Gross
Robert Gross
Poor adherence to combined antiretroviral therapy (cART) has been shown to be a major determinant of virologic failure, emergence of drug resistant virus, disease progression, hospitalizations, mortality, and health care costs. While high adherence levels can be achieved in both resource-rich and resource-limited settings following initiation of cART, long-term adherence remains a challenge regardless of available resources. Barriers to optimal adherence may originate from individual (biological, socio-cultural, behavioral), pharmacological, and societal factors. Although patients and providers should continuously strive for maximum adherence to cART, there is accumulating evidence that each class of antiretroviral therapy has specific adherence-drug resistance relationship characteristics allowing certain regimens more flexibility than others. There is not a universally accepted measure for cART adherence, since each method has distinct advantages and disadvantages including cost, complexity, accuracy, precision, intrusiveness and bias. Development of a real-time cART adherence monitoring tool will enable the development of novel, pre-emptive adherence-improving strategies. The application of these strategies may ultimately prove to be the most cost-effective method to reduce morbidity and mortality for the individual and decrease the likelihood of HIV transmission and emergence of resistance in the community.

7 October 2022 in Science
Verified
Journal Article
Closed access
HTHouriiyah Tegally
Houriiyah Tegally
JSJames Emmanuel San
James Emmanuel San
MCMatthew Cotten
Matthew Cotten
MMMonika Moir
Monika Moir
BTBryan Tegomoh
Bryan Tegomoh
EWEduan Wilkinson
Eduan Wilkinson
Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern—particularly Alpha, Beta, Delta, and Omicron—on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century.

22 October 2021 in Science
Verified
Journal Article
Open access
EWEduan Wilkinson
Eduan Wilkinson
Marta GiovanettiMarta Giovanetti
Marta Giovanetti
HTHouriiyah Tegally
Houriiyah Tegally
JSJames Emmanuel San
James Emmanuel San
RLRichard Lessells
Richard Lessells
TOTulio De Oliveira
Tulio De Oliveira
SARS-CoV-2 across Africa: The impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been hard to track in African countries, largely because of patchy data. Wilkinson et al . curated viral genomes collected in 2021 from several countries across the continent. Outbreaks during 2020 in each African country were initiated by imported cases, mostly from Europe. As the pandemic developed, case numbers in African countries were likely many times higher than reported, and subsequent waves of the pandemic appear to have been more severe. Consequently, high-transmission variants have emerged that have spread within the continent, and African countries must be included in global control efforts. —CA

31 January 2017 in Southern African Journal of HIV Medicine
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Journal Article
Open access
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GMGraeme Meintjes
Graeme Meintjes
MMMichelle A. Moorhouse
Michelle A. Moorhouse
SCSergio Carmona
Sergio Carmona
NDNatasha Davies
Natasha Davies
SDSipho Dlamini
Sipho Dlamini
FVFrancois Venter
Francois Venter
These guidelines are intended as an update to those published in the Southern African Journal of HIV Medicine in 2014 and the update on when to initiate antiretroviral therapy in 2015. Since the release of the previous guidelines, the scale-up of antiretroviral therapy (ART) in southern Africa has continued. New antiretroviral drugs have become available with improved efficacy, safety and robustness. The guidelines are intended for countries in the southern African region, which vary between lower and middle income.

15 June 2013 in The Journal of Infectious Diseases
Verified
Journal Article
Open access
PDF file
MHMina Hosseinipour
Mina Hosseinipour
RGRavindra Gupta
Ravindra Gupta
GZGert van Zyl
Gert van Zyl
JEJoseph J. Eron
Joseph J. Eron
JNJean B. Nachega
Jean B. Nachega
Antiretroviral therapy (ART) in resource-limited settings has expanded in the last decade, reaching >8 million individuals and reducing AIDS mortality and morbidity. Continued success of ART programs will require understanding the emergence of HIV drug resistance patterns among individuals in whom treatment has failed and managing ART from both an individual and public health perspective. We review data on the emergence of HIV drug resistance among individuals in whom first-line therapy has failed and clinical and resistance outcomes of those receiving second-line therapy in resource-limited settings. Resistance surveys among patients initiating first-line nonnucleoside reverse-transcriptase inhibitor (NNRTI)–based therapy suggest that 76%–90% of living patients achieve HIV RNA suppression by 12 months after ART initiation. Among patients with detectable HIV RNA at 12 months, HIV drug resistance, primarily due to M184V and NNRTI mutations, has been identified in 60%–72%, although the antiretroviral activity of proposed second-line regimens has been preserved. Complex mutation patterns, including thymidine-analog mutations, K65R, and multinucleoside mutations, are prevalent among cases of treatment failure identified by clinical or immunologic methods. Approximately 22% of patients receiving second-line therapy do not achieve HIV RNA suppression by 6 months, with poor adherence, rather than HIV drug resistance, driving most failures. Major protease inhibitor resistance at the time of second-line failure ranges from 0% to 50%, but studies are limited. Resistance of HIV to first-line therapy is predictable at 12 months when evaluated by means of HIV RNA monitoring and, when detected, largely preserves second-line therapy options. Optimizing adherence, performing resistance surveillance, and improving treatment monitoring are critical for long-term prevention of drug resistance.