Browsing by Author "Bernitz, Netanya"

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    HIV-1 subtype C envelope function becomes less sensitive to N-glycosylation deletion during disease progression
    (BMC (part of Springer Nature), 2019-06-17) Lumngwena, Evelyn N.; Shuping, Liliwe; Bernitz, Netanya; Woodman, Zenda
    Objective: As part of a larger study to understand how Envelope N-glycosylation influences HIV-1 pathogenesis, we selected a participant infected with a single Subtype C variant and determined whether deletion of specific potential N-glycan sites (PNGs) impacted Envelope function longitudinally. Results: We deleted five PNGs previously linked to HIV-1 transmission of two matched Envelope clones representing variants at 5 and 173 weeks post-infection. The transmitted founder (TF) had significantly better pseudovirus entry efficiency than the chronic infection (CI) variant. Deletion of all PNGs significantly reduced TF entry efficiency, binding to dendritic cell-specific intracellular adhesion molecule 3 grabbing non-integrin (DC-SIGN) receptor and transinfection. However, mutational analysis did not affect the phenotype of the CI Envelope to the same extent. Notably, deletion of the PNGs at N241 and N448 had no effect on CI Envelope function, suggesting that some PNGs might only be important during acute infection. Therefore, vaccines that elicit antibodies against N-glycans important for TF Envelope function could drive the loss of PNGs during immune escape, abrogating viral replication. Conversely, changes in N-glycosylation might have no effect on some variants, reducing vaccine efficacy. This finding highlights the need for further investigation into the role of Envelope N-glycosylation in HIV-1 pathogenesis.
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    Novel approaches to the diagnosis of Mycobacterium bovis infection in African buffaloes (Syncerus caffer)
    (Stellenbosch : Stellenbosch University, 2019-12) Bernitz, Netanya; Miller, Michele Anne; Parsons, Sven David Charles; Du Plessis, Nelita; Stellenbosch University. Faculty Medicine and Health Sciences. Dept. of Biomedical Sciences: Molecular Biology and Human Genetics
    ENGLISH ABSTRACT: Mycobacterium bovis(M. bovis) is the pathogen that causes bovine tuberculosis (bTB) in a wide range of host species including livestock and wildlife. Globally, the control of M. bovisinfection is hindered by the existence of wildlife maintenance hosts. In South Africa, African buffaloes (Syncerus caffer) are considered maintenance hosts of bTB, and therefore control in this species will facilitate control in other sympatric wildlife species and livestock. With the limited availability of diagnostic tools and their suboptimal test performancesto detectM. bovisinfection in buffaloes, it is imperative to develop novel approaches to improve the detection ofinfected buffaloes. In this study, the QuantiFERON®TB-Gold (QFT) system in combination with the cattletype®IFN-gamma ELISA, the QFT interferon gamma (IFN-γ)release assay (IGRA), was shown to have high specificity but poor sensitivity in detecting M. bovisinfection in buffaloes. The sensitivityof the QFT IGRA was improved by measuring the chemokineIFN-γ-inducible protein-10 (IP-10)in theQFTIP-10release assay (IPRA). When both cytokines IFN-γ and IP-10 were measured in parallel in the QFT system, sensitivity was further improved and the specificityof the individual assays were maintained. The concentrations of IFN-γ and IP-10 in QFT tubes were used to predictthe presence of macroscopic pathology in M. bovis-infected buffaloes. Lastly, the immunophenotyping of cattle whole blood identified cellular subsets of bovine leukocytes,however, the production of IP-10 in these cells wasnot confirmed. This study has demonstrated that the QFT system is a highly practical stimulation platform to detect M. bovisinfection in buffaloes with high specificity. The QFT system and novel cattletype®IFN-gammaELISA is anIGRA with high specificity that can be used to detect M. bovisinfection in buffalo populations. The cytokine IP-10 is a more sensitive biomarker than IFN-γ and when these two cytokines are measured in parallel in the QFT system, the detection of infected buffaloes is maximised, the specificityis high and the testing procedure is simplified. Finally, the magnitude of IP-10 and IFN-γ concentrations in QFT-processed whole blood can be usedas indicators of bTB pathology in M. bovis-infected buffaloes
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    Review of diagnostic tests for detection of mycobacterium bovis infection in South African wildlife
    (Frontiers Media S.A, 2021-01) Bernitz, Netanya; Kerr, Tanya J.; Goosen, Wynand J.; Chileshe, Josephine; Higgitt, Roxanne L.; Roos, Eduard O.; Meiring, Christina; Gumbo, Rachiel; De Waal, Candice; Clarke, Charlene; Smith, Katrin; Goldswain, Samantha; Sylvester, Taschnica T.; Kleynhans, Léanie; Dippenaar, Anzaan; Buss, Peter E.; Cooper, David V.; Lyashchenko, Konstantin P.; Warren, Robin M.; Van Helden, Paul D.; Parsons, Sven D. C.; Miller, Michele A.
    Wildlife tuberculosis is a major economic and conservation concern globally. Bovine tuberculosis (bTB), caused byMycobacteriumbovis (M. bovis), is themost common form of wildlife tuberculosis. In South Africa, to date, M. bovis infection has been detected in 24 mammalian wildlife species. The identification of M. bovis infection in wildlife species is essential to limit the spread and to control the disease in these populations, sympatric wildlife species and neighboring livestock. The detection of M. bovis-infected individuals is challenging as only severely diseased animals show clinical disease manifestations and diagnostic tools to identify infection are limited. The emergence of novel reagents and technologies to identify M. bovis infection in wildlife species are instrumental in improving the diagnosis and control of bTB. This review provides an update on the diagnostic tools to detect M. bovis infection in South African wildlife but may be a useful guide for other wildlife species.