Browsing by Author "De Beer, Corena"
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- ItemAnti-HIV-1 activity of salivary MUC5B and MUC7 mucins from HIV patients with different CD4 counts(BioMed Central, 2010-10) Habte, Habtom H.; De Beer, Corena; Lotz, Zoe E.; Roux, Paul; Mall, Anwar S.Background: We have previously shown that MUC5B and MUC7 mucins from saliva of HIV negative individuals inhibit HIV-1 activity by 100% in an in vitro assay. The purpose of this subsequent study was to investigate whether MUC5B and MUC7 from saliva of HIV patients or with full blown AIDS had a similar inhibitory activity against the virus. Methods Salivary MUC5B and MUC7 from HIV patients with different CD4 counts (< 200, 200-400 and > 400) were incubated with HIV-1 prior to infection of the human T lymphoblastoid cell line (CEM SS cells). Cells were then cultured and viral replication was measured by a qualitative p24 antigen assay. The size, charge and immunoreactivity of mucins from HIV negative and positive individuals was also analysed by SDS-PAGE, Western blot and ELISA respectively. Results: It was shown that irrespective of their CD4 counts both MUC5B and MUC7 from HIV patients, unlike the MUC5B and MUC7 from HIV negative individuals, did not inhibit HIV-1 activity. Size, charge and immunoreactivity differences between the mucins from HIV negative and positive individuals and among the mucins from HIV patients of different CD4 count was observed by SDS-PAGE, Western blot and ELISA. Conclusions: Purified salivary mucins from HIV positive patients do not inhibit the AIDS virus in an in vitro assay. Although the reason for the inability of mucins from infected individuals to inhibit the virus is not known, it is likely that there is an alteration of the glycosylation pattern, and therefore of charge of mucin, in HIV positive patients. The ability to inhibit the virus by aggregation by sugar chains is thus diminished.
- ItemAntibody responses to vaccination among South African HIV-exposed and unexposed uninfected infants during the first 2 years of life(American Society for Microbiology, 2013-01) Reikie, Brian A.; Naidoo, Shalena; Ruck, Candice E.; Slogrove, Amy L.; De Beer, Corena; La Grange, Heleen; Adams, Rozanne C. M.; Ho, Kevin; Smolen, Kinga; Speert, David P.; Cotton, Mark F.; Preiser, Wolfgang; Esser, Monika; Kollmann, Tobias R.HIV-exposed but uninfected (HEU) infants born to HIV-infected mothers from areas in the world with a high burden of infectious disease suffer higher infectious morbidity and mortality than their HIV unexposed uninfected (HUU) peers. Vaccination provides protection from infection. The possibility exists that altered response to vaccination contributes to the higher rate of infection in HEU than in HUU infants. While short-term, cross-sectional studies support this notion, it is unclear whether or not HEU infants develop long-term protective immune responses following theWHOextended program on immunization (EPI). Vaccine-specific antibody responses were compared between HEU and HUU infants from 2 weeks until 2 years of age in a longitudinal South African cohort. Total IgG and antibodies specific for Bordetella pertussis, Haemophilus influenzae type b (Hib), tetanus toxoid, hepatitis B virus (HepB), and measles virus were measured at multiple time points throughout the first 2 years of life. Prevaccine antibodies (maternal antibodies passively acquired) specific for tetanus were lower in HEU than in HUU infants, while prevaccine antibodies to HepB were higher in HEU than in HUU infants. Both groups responded similarly to tetanus, Hib, and HepB vaccination. HEU demonstrated stronger pertussis vaccine responses, developing protective titers 1 year earlier than HUU patients, and maintained higher anti-tetanus titers at 24 months of age. Vaccine-induced antibodies to measles virus were similar in both groups at all time points. Our results suggest that the current EPI vaccination program as practiced in South Africa leads to the development of vaccine-specific antibody responses that are equivalent in HEU and HUU infants. However, our data also suggest that a large fraction of both HEU and HUU South African infants have antibody titers for several infectious threats that remain below the level of protection for much of their first 2 years of life.
- ItemClinical and laboratory investigation of latex allergy in healthcare workers(Stellenbosch : Stellenbosch University, 2004-12) De Beer, Corena; Walzl, Gerhard; Cilliers, Jacques; Stellenbosch University. Faculty of Medicine & Health Sciences. Dept. of Biomedical Sciences. Molecular Biology and Human Genetics.ENGLISH ABSTRACT: Healthcare workers (HCWs) wear latex gloves to protect themselves and their patients against the transmission of microbial, viral and bloodborne diseases. These individuals are primarily exposed to latex via cutaneous (direct contact) and mucocutaneous (inhalation of airborne allergens on glove powder) routes. Repeated exposure leads to the formation of circulating latex-specific IgE and subsequent sensitisation with varying clinical expression. The airconditioning system of the Tygerberg Hospital (TBH) complex was investigated for the presence of aerosolised cornstarch glove powder and proteins. Dust samples were collected from 14 areas with different levels of latex glove usage. Dust samples were spectrophotometrically compared to a calibration graph of pure glove powder. The detection of starch and proteins in all the dust samples confirmed the presence of glove powder and possibly airborne latex allergens in the airconditioning ducts. As expected, the high exposure areas showed the highest concentrations of both starch and proteins. It is possible that other proteins than latex were involved, but the confirmed high level of protein contamination should be a cause for concern. Correlation between starch and protein levels was highly significant (p<0.01) in all instances. A total of 500 questionnaires were circulated for completion by HCWs from TBH. The response rate was 69.8%. After considering specific inclusion criteria, a study group of 152 individuals was compiled (28 males, 124 females). All subjects had current latex exposure and suffered from at least three pre-defined symptoms. Serum was collected from all subjects and dermal fluid from 31 subjects. Total IgE and latex specific IgE analysis were done on all serum and dermal fluid samples. Latex-specific IgE was positive (>0.35 IU/ℓ) in 23 serum and six dermal fluid samples. Skin prick tests (SPTs)for latex were done on 59 subjects with negative serum latex-specific IgE and 34 had positive results. Twelve subjects with negative latex-specific IgE and latex SPTs underwent patch tests with the European Standard Series, a piece of latex glove and glove powder in petrolatum. Three subjects had positive results to one or more of these allergens. Western blot analysis for latex was done on all positive sera and dermal fluid collected from these subjects. Western blot analysis for latex proved to be more sensitive than the capRAST, because it was able to identify specific bands in samples with negative capRAST results. All subjects showed a band for Hev b 1, which has been confirmed as a powder-bound airborne allergen. Hev b 6.01 is associated with HCWs with cutaneous symptoms and this band was recognised by 81% of the subjects. These findings confirmed that airborne and cutaneous routes are the major routes of exposure in HCWs. According to their laboratory results, subjects were divided into the following subgroups and compared statistically: Group A (serum positive, n=23), Group B (SPT positive, n=34) and Group C (negative, n=25). Group D (withdrawn, n=70) could not be used for statistical comparisons, due to incomplete results. An overall latex allergy prevalence of 38% was found. Group A differed significantly from Group B and Group C for most clinical and special investigations. Group A and B were also combined to represent all subjects with positive results (Cohort AB). The Allergy Score and Class were highly significant when Cohort AB was compared to Group C. The selection of clinical symptoms was confirmed to be relevant and work-related deterioration on any of the symptoms should bear a high index of suspicion in the evaluation of latex allergy. Numerical indices and specific symptoms showed high positive predictive values and the Allergy Score produced statistical significance in the positive subgroups when compared to the negative subgroup. Paired statistical significance was confirmed between the Allergy Score and occupational exposure (number of years, hours and pairs per week). The areas with the highest occupational latex exposure in HCWs are the face and hands. Different occupations also have different levels of exposure and two subgroups of HCWs (16 laboratory technologists and 13 theatre staff) were investigated for sebum content on different facial areas and the palms and dorsal areas of both hands. Baseline measurements were done before putting on gloves. In 21 subjects follow up measurements were done following three to four hours of occupational exposure, but before washing their hands. Baseline and follow up values were compared for all the different anatomical regions. Levels on the forehead and cheeks increased over time, while the level on the nose decreased. All hand regions decreased significantly during occupational exposure, suggesting that glove powder contributes to dryness of the skin. In conclusion, the problem posed by latex allergy will not be solved overnight and will probably remain a major occupational hazard for years to come. It is currently not possible to avoid exposure to latex, but it is imperative to institute safety measures to prevent further sensitisation in predisposed individuals and manage those already affected.
- ItemDiagnostic options for investigating viral respiratory pathogens in sudden unexpected death in infancy (SUDI) cases(JSciMed Central, 2014) De Beer, Corena; La Grange, HeleenSudden and unexpected deaths in infants have occurred for centuries. It has generally been referred to as sudden infant death syndrome (SIDS). A new concept, called sudden unexpected death in infancy (SUDI) was introduced in 1989, which is used for all unexpected deaths in infants and babies, usually during sleep, where fatal injury can be excluded. By definition, cases that remain unexplained after thorough investigation are still classified as SIDS. Many risk factors have been associated with SUDI, e.g. poor socioeconomic conditions and prenatal care, multiple pregnancies, parental drug use and smoking, gender, low birth weight, recent infection and the sleeping environment. Ultimately, SUDI is most probably a result of a combination of predisposing factors, external stresses and underlying vulnerabilities, although the exact mechanism of death remains unknown. Viral infections are common in infants and have repeatedly been implicated in SUDI. Respiratory infections occur frequently in infancy and early childhood and inflammatory changes in the respiratory tract in SUDI cases is often found. Different diagnostic approaches for investigating respiratory viruses in SUDI cases have been reported in the literature, but in the absence of standardised SUDI investigation protocols, research from different centres cannot be compared. Viral viability is compromised in post-mortem samples and results should be interpreted with care, as the mere presence of a pathogen does not confirm that to be the cause of death. It is therefore imperative to use a combination of diagnostic approaches in parallel with epidemiological and clinical information in SUDI cases.
- ItemImmune biomarkers as an adjunct diagnostic modality of infection in cases of sudden and unexpected death in infancy (SUDI) at Tygerberg Medico-legal Mortuary, Cape Town, South Africa(Elsevier, 2021) De Beer, Corena; Ayele, Birhanu T.; Dempers, JohanENGLISH ABSTRACT: Child mortality is a major health concern worldwide with over 4.2 million infants dying before reaching the age of one year in 2016 alone. Several international intervention initiatives have resulted in a decrease in the number of infant deaths; however, the incidence of sudden unexpected death in infancy (SUDI) and sudden infant death syndrome (SIDS) remain unacceptably high. SIDS still accounts for approximately 50–80% of SUDI cases, followed by infection. The aim of this study was to investigate a selection of immune biomarkers that are associated with an immune response in an effort to support the diagnosis of an infectious cause (“Infection”) e.g. bronchopneumonia, interstitial pneumonitis, etc., instead of SIDS in SUDI cases. C-reactive protein and 18 different cytokines were retrospectively quantified in serum collected during post-mortem investigations of SUDI cases admitted to the Tygerberg Medico-legal Mortuary in the Western Cape Province of South Africa between 2015 and 2017. Statistical comparison was done between infants with a final cause of death (COD) of Infection and SIDS to investigate any correlations between the immune markers and sociodemographic information of the groups. A p-value of < 0.0026, after Bonferroni correction for multiple comparisons, was considered as statistically significant. A total of 169 cases were included, of which 65 (38.5%) were assigned a cause of death of Infection and 104 (61.5%) SIDS by forensic pathologists. The male to female ratio of the entire group was 1:0.97 and the median age at the time of death was 9 (interquartile range [IQR] 10.9) weeks. The majority (56.8%) of deaths occurred during the colder seasons (autumn and winter) and the median post-mortem interval was 4 (IQR 3) days. No statistically significant differences were demonstrated for gender, season, sleeping position or bed-sharing between the Infection and SIDS groups. Age and interleukin-1α were identified as predictors of a COD of Infection before adjusting for the multiple comparisons problem. C-reactive protein was a statistically significant predictor of a COD of Infection even after adjusting for the effect of multiple comparisons. The COD is primarily based on histopathology of the lungs, where other causes of interstitial inflammation have been ruled out, and where there are morphological changes present suggestive of infection, but not enough evidence to assign a final COD of Infection, the cases are concluded as SIDS. These biomarkers can therefore be valuable in the investigation protocol of SUDI cases to increase the number Infection cases where the histopathology of the lungs is suggestive of, but does not support conclusive evidence of infection.
- ItemThe inhibition of the Human Immunodeficiency Virus type 1 activity by crude and purified human pregnancy plug mucus and mucins in an inhibition assay(BioMed Central, 2008-05) Habte, Habtom H.; De Beer, Corena; Lotz, Zoe E.; Tyler, Marilyn G.; Schoeman, Leann; Kahn, Delawir; Mall, Anwar S.Background: The female reproductive tract is amongst the main routes for Human Immunodeficiency Virus (HIV) transmission. Cervical mucus however is known to protect the female reproductive tract from bacterial invasion and fluid loss and regulates and facilitates sperm transport to the upper reproductive tract. The purpose of this study was to purify and characterize pregnancy plug mucins and determine their anti-HIV-1 activity in an HIV inhibition assay. Methods: Pregnancy plug mucins were purified by caesium chloride density-gradient ultra-centrifugation and characterized by Western blotting analysis. The anti-HIV-1 activities of the crude pregnancy plug mucus and purified pregnancy plug mucins was determined by incubating them with HIV-1 prior to infection of the human T lymphoblastoid cell line (CEM SS cells). Results: The pregnancy plug mucus had MUC1, MUC2, MUC5AC and MUC5B. The HIV inhibition assay revealed that while the purified pregnancy plug mucins inhibit HIV-1 activity by approximately 97.5%, the crude pregnancy plug mucus failed to inhibit HIV-1 activity. Conclusion: Although it is not clear why the crude sample did not inhibit HIV-1 activity, it may be that the amount of mucins in the crude pregnancy plug mucus (which contains water, mucins, lipids, nucleic acids, lactoferrin, lysozyme, immunoglobulins and ions), is insufficient to cause viral inhibition or aggregation.
- ItemMucus and mucins: do they have a role in the inhibition of the human immunodeficiency virus?(BioMed Central, 2017-10-06) Mall, Anwar Suleman; Habte, Habtom; Mthembu, Yolanda; Peacocke, Julia; De Beer, CorenaBackground: Mucins are large O-linked glycosylated proteins which give mucus their gel-forming properties. There are indications that mucus and mucins in saliva, breast milk and in the cervical plug inhibit the human immunodeficiency virus (HIV-1) in an in vitro assay. Main body of abstract: Crude mucus gels form continuous layers on the epithelial surfaces of the major internal tracts of the body and protect these epithelial surfaces against aggressive luminal factors such as hydrochloric acid and pepsin proteolysis in the stomach lumen, the movement of hard faecal pellets in the colon at high pressure, the effects of shear against the vaginal epithelium during intercourse and the presence of foreign substances in the respiratory airways. Tumour-associated epitopes on mucins make them suitable as immune-targets on malignant epithelial cells, rendering mucins important as diagnostic and prognostic markers for various diseases, even influencing the design of mucin-based vaccines. Sub-Saharan Africa has the highest prevalence of HIV-AIDS in the world. The main points of viral transmission are via the vaginal epithelium during sexual intercourse and mother-to-child transmission during breast-feeding. There have been many studies showing that several body fluids have components that prevent the transmission of HIV-1 from infected to non-infected persons through various forms of contact. Crude saliva and its purified mucins, MUC5B and MUC7, and the purified mucins from breast milk, MUC1 and MUC4 and pregnancy plug cervical mucus (MUC2, MUC5AC, MUC5B and MUC6), inhibit HIV-1 in an in vitro assay. There are conflicting reports of whether crude breast-milk inhibits HIV-1 in an in vitro assay. However studies with a humanised BLT mouse show that breast-milk does inhibit HIV and that breast-feeding is still advisable even amongst HIV-positive women in under-resourced areas, preferably in conjunction with anti-retroviral treatment. Conclusion: These findings raise questions of how such a naturally occurring biological substance such as mucus, with remarkable protective properties of epithelial surfaces against aggressive luminal factors in delicate locations, could be used as a tool in the fight against HIV-AIDS, which has reached epidemic proportions in sub-Saharan Africa.
- ItemOntogeny of toll-like receptor mediated cytokine responses of South African infants throughout the first year of life(Public Library of Science, 2012-09-13) Reikie, Brian A.; Adams, Rozanne C. M.; Ruck, Candice E.; Ho, Kevin; Leligdowicz, Aleksandra; Pillay, Santoshan; Naidoo, Shalena; Fortuno III, Edgardo S.; De Beer, Corena; Preiser, Wolfgang; Cotton, Mark F.; Speert, David P.; Esser, Monika; Kollmann, Tobias R.The first year of life represents a time of marked susceptibility to infections; this is particularly true for regions in sub-Saharan Africa. As innate immunity directs the adaptive immune response, the observed increased risk for infection as well as a suboptimal response to vaccination in early life may be due to less effective innate immune function. In this study, we followed a longitudinal cohort of infants born and raised in South Africa over the first year of life, employing the most comprehensive analysis of innate immune response to stimulation published to date. Our findings reveal rapid changes in innate immune development over the first year of life. This is the first report depicting dramatic differences in innate immune ontogeny between different populations in the world, with important implications for global vaccination strategies.
- ItemOptimising automation of a manual enzyme-linked immunosorbent assay(AOSIS Publishing, 2012-10) De Beer, Corena; Esser, Monika; Preiser, WolfgangObjective: Enzyme-linked immunosorbent assays (ELISAs) are widely used to quantify immunoglobulin levels induced by infection or vaccination. Compared to conventional manual assays, automated ELISA systems offer more accurate and reproducible results, faster turnaround times and cost effectiveness due to the use of multianalyte reagents. Design: The VaccZyme™ Human Anti-Haemophilus influenzae type B (Hib) kit (MK016) from The Binding Site Company was optimised to be used on an automated BioRad PhDTM system in the Immunology Laboratory (National Health Laboratory Service) in Tygerberg, South Africa. Methods: An automated ELISA system that uses individual well incubation was compared to a manual method that uses whole-plate incubation. Results: Results were calculated from calibration curves constructed with each assay. Marked differences in calibration curves were observed for the two methods. The automated method produced lower-than-recommended optical density values and resulted in invalid calibration curves and diagnostic results. A comparison of the individual steps of the two methods showed a difference of 10 minutes per incubation cycle. All incubation steps of the automated method were subsequently increased from 30 minutes to 40 minutes. Several comparative assays were performed according to the amended protocol and all calibration curves obtained were valid. Calibrators and controls were also included as samples in different positions and orders on the plate and all results were valid. Conclusion: Proper validation is vital before converting manual ELISA assays to automated or semi-automated methods.
- ItemThe role of crude human saliva and purified salivary MUC5B and MUC7 mucins in the inhibition of Human Immunodeficiency Virus type 1 in an inhibition assay(BioMed Central, 2006-11) Habte, Habtom H.; Mall, Anwar S.; De Beer, Corena; Lotz, Zoe E.; Kahn, DelawirBackground: Despite the continuous shedding of HIV infected blood into the oral cavity and the detectable presence of the AIDS virus at a high frequency, human saliva is reported to inhibit oral transmission of HIV through kissing, dental treatment, biting, and aerosolization. The purpose of this study was to purify salivary MUC5B and MUC7 mucins from crude saliva and determine their anti-HIV-1 activities. Methods: Following Sepharose CL-4B column chromatography and caesium chloride isopycnic density-gradient ultra-centrifugation, the purity and identity of the mucins was determined by SDS-PAGE and Western blotting analysis respectively. Subsequently an HIV-1 inhibition assay was carried out to determine the anti-HIV-1 activity of the crude saliva and purified salivary mucins by incubating them with subtype D HIV-1 prior to infection of the CD4+ CEM SS cells. Results: Western blotting analysis confirmed that the mucin in the void volume is MUC5B and the mucin in the included volume is MUC7. The HIV inhibition assay revealed that both the crude saliva and salivary MUC5B and MUC7 mucins inhibited HIV-1 activity by 100%. Conclusion: Although the mechanism of action is not clear the carbohydrate moieties of the salivary mucins may trap or aggregate the virus and prevent host cell entry.
- ItemThe role of crude saliva and purified salivary mucins in the inhibition of the Human Immunodeficiency Virus type 1(BioMed Central, 2012-08) Peacocke, Julia; Lotz, Zoe; De Beer, Corena; Roux, Paul; Mall, Anwar S.Background: Sub-Saharan Africa is the world’s worst HIV-AIDS affected region. More interventions to manage this pandemic are urgently required. Transmission of the virus through an exchange of saliva is rarely known to occur. This project sought to verify statistically previous findings in our laboratory, that crude saliva from uninfected individuals together with its purified mucin components inhibited HIV-1, whilst mucins from infected saliva did not show this inhibition, in an in vitro assay. Methods: Saliva was extracted in 4 M guanidinium hydrochloride and proteolytic inhibitors at pH 6.5, followed by the isolation of MUC5B and MUC7 by Sepharose 4B gel filtration and further purification of these mucins by density-gradient ultra-centrifugation in caesium chloride. Agarose gel electrophoresis, Western blotting and amino acid compositional analysis determined the size, purity and identity of the mucins. The inhibitory activity of crude saliva and purified MUC5B and MUC7, from HIV negative (n=20) and HIV positive (n=20) donors, was tested by their incubation with subtype C HIV-1 and subsequent infection of peripheral blood mononuclear cells (PBMCs). PCR was done on tandem repeat regions of MUC5B and MUC7 DNA to investigate whether any association existed between gene polymorphism and susceptibility to infection. Results: There was an inter-individual variation in the amounts of MUC5B and MUC7 in saliva. In contrast to previous studies, crude saliva and purified mucins from both HIV negative and HIV positive individuals inhibited the infection of HIV-1 in an in vitro assay. DNA analysis of the tandem repeat regions of MUC5B and MUC7 revealed no difference between groups. Conclusions: Crude saliva and its mucins, MUC5B and MUC7, from both uninfected controls and HIV positive individuals inhibited HIV-1 in an in vitro assay.