Cases of Impaired Oxidative Burst in HIV-Exposed Uninfected Infants’ Neutrophils—A Pilot Study

An increased risk of serious bacterial infections in HIV-exposed uninfected (HEU) infants has been demonstrated. Although neutrophils are essential for the protection of infants against bacterial infections, no study has investigated their profile in HEU infants to date. In this study, we assessed the function of neutrophils in HEU infants using the nitroblue tetrazolium reduction test. Among 25 HEU infants, 9 (36%) showed a reduced ability of their neutrophils to produce reactive oxygen species upon stimulation with bacteria. No alteration of total neutrophil counts was noted in the blood of HEU infants indicating that the alteration observed in the 36% of HEU infants may only be functional. Conclusively, impaired neutrophil function could be a factor of vulnerability in HEU infants

The Africa Centres for Disease Control public health emergency management fellowship: insights from the inaugural cohort

Public health emergencies remain a significant challenge across the African continent, driven largely by the high burden of infectious diseases and constraints in the public health workforce. The Africa Centre for Disease Control and Prevention (Africa CDC) has taken a strategic move towards addressing emergency preparedness and response workforce gap with the implementation of the Public Health Emergency Essone Management (PHEM) Fellowship aimed at providing African Union Member States (MS) with trained personnel in emergency management. We describe the components of this program comprised of six sections such as the advisory committee (from several countries and divers organizations), a rigorous selection process, eleven weeks of in-person classes with validated materials, field deployments in countries with ongoing emergency crises, projects and mentorship programs. The PHEM fellowship offers African countries a strategic opportunity to strengthen their public health workforce and enhance their preparedness towards potential public health emergencies

LC-MS based analysis reveal antimicrobial compounds from Gabonese pharmacopoeia: chemical characterisation and cytotoxicity evaluation

Plants used in traditional medicine represent an important source of new compounds. Hallea ledermannii (H. ledermannii) (Krause) Verdc. (Rubiaceae), Gossypium barbadense (G. barbadense) (Malvaceae), Pycnanthus angolensis (P. angolensis) (Myristicaceae), Drypetes gossweileri (D. gossweileri) S. Moore (Euphorbiaceae) and Scyphocephalium ochocoa (S. ochocoa) Warb (Myristicaceae) are five plants widely used in traditional Gabonese medicine as antimicrobials. However, little is known about the active compounds associated with their biological activities. Based on botanical studies and the claims of traditional healers regarding the antimicrobial effects of these plants, a study to evaluate the antimicrobial activity and phyto-chemical profile of aqueous extracts of three plants (bark of H. ledermannii, G. barbadense root bark and P. angolensis bark) and methanolic extracts of two plants (S. ochocoa stem bark and D. gossweileri root bark). Under the guidance of LC-MS detection, identified twenty seven (27) potentially active compounds. Eight (8) of these belong to the quinovic acid-type triterpenoid sap-onins identified in the aqueous extract of H. ledermannii, eleven (11) are dibenzofurans, chroman and stigmasterol detected in the methanolic extract of S. ochocoa and eight (8) compounds in the methanolic extract of D. gossweileri are friedelin, drypemolundein B and gossweilone, to name but a few. In parallel, the five extracts were tested on reference bacterial strains: Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 278533, Salmonella thyphi ATCC 13311, Klebsiella pneumoniae ATCC 700603, Shigella flexneri ATCC 24570. Three of these extracts (aqueous extract of H. ledermannii and two methanolic extracts of S. ochocoa stem bark and D. gossweileri root bark) showed moderate activity against Staphylococcus aureus ATCC 25923, with inhibition zones of 12.3 ± 0.5 mm, 10.1 ± 0.5 mm and 7,6 ± 0 mm respectively. In addition, we assessed the toxicity of the three extracts that showed antimicrobial activity using an invertebrate model, Galleria mellonella (GM). We found that the LD varied according to the concentration of the plant material. The aqueous extract of H. ledermannii and the methanolic extracts of S. ochocoa and D. gossweileri were not toxic to G. mellonella. The LD50s (mg/mL) obtained were 93.2 mg/mL [717.2 g/kg body weight (bw)] and 100 mg/mL (762.3 g/kg bw), 95.4 mg/mL [721.1 g/kg body weight (bw)]

Cross-sectional evaluation of host biomarkers for guiding antibiotic use in bacterial and non-bacterial acute febrile illness in low- and middle-income tropical settings

Objectives: To evaluate the effectiveness of 18 different host biomarkers in differentiating bacterial from non-bacterial acute febrile illness (AFI) in resource-limited settings, specifically in Brazil, Malawi and Gabon. Design: Multinational, cross-sectional study. Setting: The study was carried out across multiple primary healthcare facilities, including urban and rural settings, with a total of three participating centres. Recruitment took place from October 2018 to July 2019 in Brazil, May to November 2019 in Gabon and April 2017 to April 2018 in Malawi. Participants: A total of 1915 participants, including children and adults aged 21–65 years with a fever of≤7 days, were recruited through convenience sampling from outpatient clinics in Brazil, Gabon and Malawi. Individuals with signs of severe illness were excluded. Written consent was obtained from all participants or their guardians. Intervention: This is not applicable as the study primarily focused on biomarker evaluation without specific therapeutic interventions. Primary and secondary outcome measures: The primary outcome measure was the ability of each host biomarker to differentiate between bacterial and non-bacterial AFI, as evaluated by area under the receiver operating characteristic (AUROC) curves. Secondary outcomes included the performance of individual biomarkers across the different study sites and in a multivariable setting. Results: A Kruskal-Wallis test, adjusted by Benjamini-Hochberg, was performed for each biomarker to identify covariates with a significant difference in the distribution of biomarker values. The analysis revealed that country of origin (Brazil, Gabon, Malawi), age, sex and malaria status significantly impacted biomarker distribution (p≤0.001). The most widely known biomarkers, such as white blood cell (WBC) count and C-reactive protein (CRP), demonstrated the best performance in distinguishing between bacterial and non-bacterial infections, with AUROCs reaching up to 0.83 (0.77–0.88) for WBC count and 0.71 (0.59–0.82) for CRP. However, none of the evaluated novel host biomarkers exhibited high performance (AUROC<0.70 in most cases) and variations in biomarker performance were observed across the three settings. Multivariable analyses demonstrated that while the best combination of biomarkers achieved higher AUROCs, the increase was modest (1–13%), suggesting that the interaction of biomarkers contributed minimally to predictive accuracy. Conclusions: There is a continued need for innovation in the host-biomarker space as the available markers do not meet the needs of diverse populations around the globe. This highlights the importance of targeted evaluations in non-severe patients in multiple settings to understand the true potential for real-life use. The findings highlight that not one-marker fits all settings and novel innovations remain urgently needed. Trial registration number: Clinical trial number: NCT03047642

Potential of novel Mycobacterium tuberculosis infection phase-dependent antigens in the diagnosis of TB disease in a high burden setting

<p>Abstract</p> <p>Background</p> <p>Confirming tuberculosis (TB) disease in suspects in resource limited settings is challenging and calls for the development of more suitable diagnostic tools. Different <it>Mycobacterium tuberculosis (M.tb) </it>infection phase-dependent antigens may be differentially recognized in infected and diseased individuals and therefore useful as diagnostic tools for differentiating between <it>M.tb </it>infection states. In this study, we assessed the diagnostic potential of 118 different <it>M.tb </it>infection phase-dependent antigens in TB patients and household contacts (HHCs) in a high-burden setting.</p> <p>Methods</p> <p>Antigens were evaluated using the 7-day whole blood culture technique in 23 pulmonary TB patients and in 19 to 21 HHCs (total n = 101), who were recruited from a high-TB incidence community in Cape Town, South Africa. Interferon-gamma (IFN-γ) levels in culture supernatants were determined by ELISA.</p> <p>Results</p> <p>Eight classical TB vaccine candidate antigens, 51 DosR regulon encoded antigens, 23 TB reactivation antigens, 5 TB resuscitation promoting factors (rpfs), 6 starvation and 24 other stress response-associated TB antigens were evaluated in the study. The most promising antigens for ascertaining active TB were the rpfs (Rv0867c, Rv2389c, Rv2450c, Rv1009 and Rv1884c), with Areas under the receiver operating characteristics curves (AUCs) between 0.72 and 0.80. A combination of <it>M.tb </it>specific ESAT-6/CFP-10 fusion protein, Rv2624c and Rv0867c accurately predicted 73% of the TB patients and 80% of the non-TB cases after cross validation.</p> <p>Conclusions</p> <p>IFN-γ responses to TB rpfs show promise as TB diagnostic candidates and should be evaluated further for discrimination between <it>M.tb </it>infection states.</p

Potential of Host Markers Produced by Infection Phase-Dependent Antigen-Stimulated Cells for the Diagnosis of Tuberculosis in a Highly Endemic Area

CITATION: Chegou, N. N. et al. 2012. Potential of host markers produced by infection phase-dependent antigen-stimulated cells for the diagnosis of tuberculosis in a highly endemic area. PLoS ONE, 7(6): e38501, doi:10.1371/journal.pone.0038501.The original publication is available at http://journals.plos.org/plosoneBackground: Recent interferon gamma (IFN-γ)-based studies have identified novel Mycobacterium tuberculosis (M.tb) infection phase-dependent antigens as diagnostic candidates. In this study, the levels of 11 host markers other than IFN-γ, were evaluated in whole blood culture supernatants after stimulation with M.tb infection phase-dependent antigens, for the diagnosis of TB disease. Methodology and Principal Findings: Five M.tb infection phase-dependent antigens, comprising of three DosR-regulon-encoded proteins (Rv2032, Rv0081, Rv1737c), and two resucitation promoting factors (Rv0867c and Rv2389c), were evaluated in a case-control study with 15 pulmonary TB patients and 15 household contacts that were recruited from a high TB incidence setting in Cape Town, South Africa. After a 7-day whole blood culture, supernatants were harvested and the levels of the host markers evaluated using the Luminex platform. Multiple antigen-specific host markers were identified with promising diagnostic potential. Rv0081-specific levels of IL-12(p40), IP-10, IL-10 and TNF-α were the most promising diagnostic candidates, each ascertaining TB disease with an accuracy of 100%, 95% confidence interval for the area under the receiver operating characteristics plots, (1.0 to 1.0). Conclusions: Multiple cytokines other than IFN-γ in whole blood culture supernatants after stimulation with M.tb infection phase-dependent antigens show promise as diagnostic markers for active TB. These preliminary findings should be verified in well-designed diagnostic studies employing short-term culture assays. © 2012 Chegou et al.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0038501Publisher's versio

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance.

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

Altered Toll-Like Receptor-4 Response to Lipopolysaccharides in Infants Exposed to HIV-1 and Its Preventive Therapy

Pathogen sensing and recognition through pattern recognition receptors, and subsequent production of pro-inflammatory cytokines, is the cornerstone of the innate immune system. Despite the fact that HIV-exposed uninfected (HEU) infants are prone to serious bacterial infections, no study has focused on the functionality of their bacteria recognition system. This is the first study to investigate baseline levels of three critically important immune response molecules in this population: complement component (C)-3, toll-like receptor (TLR)-4, and C-reactive protein (CRP). We enrolled 16 HEU and 6 HIV-unexposed (HU) infants. TLR4 function was investigated by stimulating whole blood with increasing concentrations of TLR4-agonist ultrapure lipopolysaccharides. TLR4/TLR4-agonist dose response were assessed by measuring IL-6 secretion. Complement C3 and CRP were measured by photo spectrometry. Data showed no significant differences in baseline concentration of CRP between HEU and HU infants. Complement C3 was significantly higher in HEU infants than HU infants. TLR4 anergy was observed in 7 of 12 HEU infants, whereas the rest of HEU infants (n = 4) and the control HU infants tested (n = 3) showed responsive TLR4. None of the HEU infants investigated in this study had severe infections in the year after their birth. In conclusion, TLR4 anergy can occur in HEU infants without necessarily translating to increased vulnerability to infectious diseases