Publications by authors named "Joel Fleury Djoba Siawaya"

23 Publications

  • Page 1 of 1

Dynamic and features of SARS-CoV-2 infection in Gabon.

Sci Rep 2021 05 6;11(1):9672. Epub 2021 May 6.

Unité de Recherche et Diagnostics Spécialisé, Service Laboratoire, CHU-Mère-EnfantFondation Jeanne EBORI, Libreville, Gabon.

In a context where SARS-CoV-2 population-wide testing is implemented, clinical features and antibody response in those infected have never been documented in Africa. Yet, the information provided by analyzing data from population-wide testing is critical to understand the infection dynamics and devise control strategies. We described clinical features and assessed antibody response in people screened for SARS-CoV-2 infection. We analyzed data from a cohort of 3464 people that we molecularly screened for SARS-CoV-2 infection in our routine activity. We recorded people SARS-CoV-2 diagnosis, age, gender, blood types, white blood cells (WBC), symptoms, chronic disease status and time to SARS-CoV-2 RT-PCR conversion from positive to negative. We calculated the age-based distribution of SARS-CoV-2 infection, analyzed the proportion and the spectrum of COVID-19 severity. Furthermore, in a nested sub-study, we screened 83 COVID-19 patients and 319 contact-cases for anti-SARS-CoV-2 antibodies. Males and females accounted for respectively 51% and 49% of people screened. The studied population median and mean age were both 39 years. 592 out of 3464 people (17.2%) were diagnosed with SARS-CoV-2 infection with males and females representing, respectively, 53% and 47%. The median and mean ages of SARS-CoV-2 infected subjects were 37 and 38 years respectively. The lowest rate of infection (8%) was observed in the elderly (aged > 60). The rate of SARS-Cov-2 infection in both young (18-35 years old) and middle-aged adults (36-60 years old) was around 20%. The analysis of SARS-CoV-2 infection age distribution showed that middle-aged adults accounted for 54.7% of SARS-CoV-2 positive persons, followed respectively by young adults (33.7%), children (7.7%) and elderly (3.8%). 68% (N = 402) of SARS-CoV-2 infected persons were asymptomatic, 26.3% (N = 156) had influenza-like symptoms, 2.7% (N = 16) had influenza-like symptoms associated with anosmia and ageusia, 2% (N = 11) had dyspnea and 1% (N = 7) had respiratory failure, which resulted in death. Data also showed that 12% of SARS-CoV-2 infected subjects, had chronic diseases. Hypertension, diabetes, and asthma were the top concurrent chronic diseases representing respectively 58%, 25% and 12% of recorded chronic diseases. Half of SARS-CoV-2 RT-PCR positive patients were cured within 14 days following the initiation of the anti-COVID-19 treatment protocol. 78.3% of COVID-19 patients and 55% of SARS-CoV-2 RT-PCR confirmed negative contact-cases were positive for anti-SARS-CoV-2 antibodies. Patients with severe-to-critical illness have higher leukocytes, higher neutrophils and lower lymphocyte counts contrarily to asymptomatic patients and patients with mild-to-moderate illness. Neutrophilic leukopenia was more prevalent in asymptomatic patients and patients with mild-to-moderate disease for 4 weeks after diagnosis (27.1-42.1%). In Patients with severe-to-critical illness, neutrophilic leukocytosis or neutrophilia (35.6-50%) and lymphocytopenia (20-40%) were more frequent. More than 60% of participants were blood type O. It is also important to note that infection rate was slightly higher among A and B blood types compared with type O. In this African setting, young and middle-aged adults are most likely driving community transmission of COVID-19. The rate of critical disease is relatively low. The high rate of anti-SARS-CoV-2 antibodies observed in SARS-CoV-2 RT-PCR negative contact cases suggests that subclinical infection may have been overlooked in our setting.
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http://dx.doi.org/10.1038/s41598-021-87043-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8102484PMC
May 2021

Circulating anti-SARS-CoV-2 nucleocapsid (N)-protein antibodies and anti-SARS-CoV-2 spike (S)-protein antibodies in an African setting: herd immunity, not there yet!

BMC Res Notes 2021 Apr 20;14(1):152. Epub 2021 Apr 20.

Service Laboratoire, Centre Hospitalier Universitaire (CHU) - Mère-Enfant), Fondation Jeanne EBORI, Libreville, Gabon.

Objective: Herd immunity is achieved when in a population, immune individuals are in a sufficiently large proportion. Neutralizing antibodies specific to SARS-CoV-2 that are produced following infection or vaccination are critical for controlling the spread of COVID-19. The objective of the present work was to investigate the rate of SARS-CoV-2 natural immunization in Gabonese.

Results: One thousand, four hundred and ninety two people were enrolled. The overall prevalence of anti-SARS-CoV-2 antibodies was 36.2%. Moreover, 76.4% of people who developed a humoral response to SARS-CoV-2 produced both anti-SARS-CoV-2 N-protein antibodies and anti-SARS-CoV-2 S-protein antibodies, which correspond to 27.7% of the total population. In infants (0-9 month), children (1-17 years) and adults, the prevalence of anti-SARS-CoV-2 antibodies was relatively the same, between 33 and 37% (any antibody types) and between 25 and 28.6% (neutralizing antibodies). In this African context, one-third (1/3) of the screened population was exposed to SARS-CoV-2 and three-quarter (3/4) of those exposed individuals developed neutralizing antibodies against SARS-CoV-2. This data suggest that herd immunity is not yet to be achieved in Gabon.
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http://dx.doi.org/10.1186/s13104-021-05570-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8056361PMC
April 2021

Mycobacterium tuberculosis-stimulated whole blood culture to detect host biosignatures for tuberculosis treatment response.

Tuberculosis (Edinb) 2021 Apr 10;128:102082. Epub 2021 Apr 10.

DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.

Host markers to monitor the response to tuberculosis (TB) therapy hold some promise. We evaluated the changes in concentration of Mycobacterium tuberculosis (M.tb)-induced soluble biomarkers during early treatment for predicting short- and long-term treatment outcomes. Whole blood samples from 30 cured and 12 relapsed TB patients from diagnosis, week 1, 2, and 4 of treatment were cultured in the presence of live M.tb for seven days and patients followed up for 24 weeks after the end of treatment. 57 markers were measured in unstimulated and antigen-stimulated culture supernatants using Luminex assays. Top performing multi-variable models at diagnosis using unstimulated values predicted outcome at 24 months after treatment completion with a sensitivity of 75.0% (95% CI, 42.8-94.5%) and specificity of 72.4% (95% CI, 52.8-87.3%) in leave-one-out cross validation. Month two treatment responder classification was correctly predicted with a sensitivity of 79.2% (95% CI, 57.8-92.9%) and specificity of 92.3% (95% CI, 64.0-99.8%). This study provides evidence of the early M.tb-specific treatment response in TB patients but shows that the observed unstimulated marker models are not outperformed by stimulated marker models. Performance of unstimulated predictive host marker signatures is promising and requires validation in larger studies.
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http://dx.doi.org/10.1016/j.tube.2021.102082DOI Listing
April 2021

Evidence and implications of pre-existing humoral cross-reactive immunity to SARS-CoV-2.

Immun Inflamm Dis 2021 03 15;9(1):128-133. Epub 2020 Dec 15.

Unité de Recherche et Diagnostics Spécialisé, Service Laboratoire, CHU-Mère-Enfant, Fondation Jeanne EBORI, Libreville, Gabon.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged throughout the world. Building knowledge around Covid-19 is crucial to devise facts based approaches to respond efficiently against this pandemic.

Aim: We aimed to investigate pre-existing humoral cross-reactive immunity to SARS-CoV-2.

Method: We have tested the reactivity against SARS-CoV-2 nucleocapsid (N) antigen of sera collected from healthy healthcare volunteers in 2014. We assessed immunoglobulins reactive against SARS-CoV-2 N-antigen using a well-validated serological platform; Elecsys assay.

Results: Sera from 32 subjects (out of 135 [23.7%]) were reactive to SARS-CoV-2 N-antigen, suggesting the presence of anti-SARS-CoV-2 N-antigen antibodies.

Conclusion: Although the clinical relevance of the observed reactivity can only be speculated and needs to be investigated, the implication of this finding for coronavirus disease 2019 seroepidemiological survey and vaccines' clinical trials is critical.
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http://dx.doi.org/10.1002/iid3.367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7860591PMC
March 2021

Purifying Selection in Human Immunodeficiency Virus-1 Gene in Perinatally Human Immunodeficiency Virus-1-Infected Children Harboring Discordant Immunological Response and Virological Nonresponse to Long-Term Antiretroviral Therapy.

J Clin Med Res 2020 Jun 4;12(6):369-376. Epub 2020 Jun 4.

Laboratoire de Virologie, Hopital Europeen Georges Pompidou, Assistance Publique-Hopitaux de Paris (AP-HP) and Universite de Paris, Paris Sorbonne Cite, Paris, France.

Background: Biological monitoring of antiretroviral treatment (ART) in human immunodeficiency virus (HIV)-infected pediatric population remains challenging. The aim of the present study was to assess the long-term HIV-1 genetic diversity in gene in HIV-1-infected children in virological failure under antiretroviral regimen adapted according to the successive World Health Organization (WHO) guidelines for resource-constrained settings.

Methods: HIV-1 diversity in gene was assessed in HIV-1-infected children and adolescents born from HIV-infected mothers (median age at follow-up: 13.8 years) in virological failure (VF) despite long-term regimen recommended by the WHO. The numbers of nonsynonymous substitutions per potential nonsynonymous site (dN) and of synonymous substitutions at potential synonymous sites (dS) in HIV-1 gene and the dN/dS ratios were used to estimate the selective pressure on circulating HIV-1.

Results: The immunological responses to ART basically corresponded to: 1) Full therapeutic failure with immunological (I) and virological nonresponses in one-quarter (24.6%) of study children ((I, VF) subgroup); 2) Discordant immunovirological responses with paradoxical high CD4 T cell counts (I) and high HIV-1 RNA load in the remaining cohort patients (75.4%) ((I, VF) subgroup). The mean dS was 1.8-fold higher in (I, VF) than (I, VF) subgroup (25.9 ± 18.4 vs. 14.3 ± 10.8). In the (I, VF) subgroup, the mean dS was 1.6-fold higher than the mean dN. Finally, the mean dN/dS ratio was 2.1-fold lower in (I, VF) than (I, VF) subgroup (0.6 ± 0.3 vs. 1.3 ± 0.7), indicating purifying selection in the immunovirological discordant (I, VF) subgroup and positive selection in the immunovirological failure (I, VF) subgroup.

Conclusions: Children and adolescents in immunovirological therapeutic failure harbor positive selection of HIV-1 strains favoring diversifying in -encoded amino acids. In contrast, children with persistent discordant immunovirological responses show accumulation of mutations and purifying selection in gene sequences, indicating limited genetic evolution and likely suggesting genetic adaptation of viruses to host functional constraints.
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http://dx.doi.org/10.14740/jocmr4157DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7295550PMC
June 2020

Escalating and sustained immunovirological dissociation among antiretroviral drug-experienced perinatally human immunodeficiency virus-1-infected children and adolescents living in the Central African Republic: A STROBE-compliant study.

Medicine (Baltimore) 2020 May;99(21):e19978

Laboratoire de virologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris (AP-HP) and Université Paris Descartes, Paris Sorbonne Cité, Paris, France.

Sub-Saharan Africa has the vast majority (∼90%) of new pediatric acquired immunodeficiency syndrome cases worldwide. Biologically monitoring HIV-infected pediatric populations remains challenging. The differential interest of human immunodeficiency virus (HIV)-1 RNA loads and CD4 T-cell counts is debated for the treatment of pediatric acquired immunodeficiency syndrome patients.Long-term antiretroviral treatment (ART) outcomes regarding immunological and virological surrogate markers were longitudinally evaluated between 2009 and 2014 (over 57 months) in 245 perinatally HIV-1-infected children and adolescents born from HIV-infected mothers, treated at inclusion for at least 6 months by the World Health Organization-recommended ART in Bangui, Central African Republic.Patients were monitored over time biologically for CD4 T-cell counts, HIV-1 RNA loads, and drug resistance mutation genotyping.Children lost to follow-up totaled 6%. Four categories of immunovirological responses to ART were observed. At baseline, therapeutic success with sustained immunological and virological responses was observed in 80 (32.6%) children; immunological and virologic nonresponses occurred in 32 (13.0%) children; finally, the majority (133; 54.2%) of the remaining children showed discordant immunovirological responses. Among them, 33 (13.4%) children showed rapid virological responses to ART with an undetectable viral load, whereas immunological responses remained absent after 6 months of treatment and increased progressively over time in most of the cases, suggesting slow immunorestoration. Notably, nearly half of the children (40.8% at baseline and 48.2% at follow-up) harbored discordant immunovirological responses with a paradoxically high CD4 T-cell count and HIV-1 RNA load, which are always associated with high levels of drug resistance mutations. The latter category showed a significant increase over time, with a growth rate of 1.23% per year of follow-up.Our STROBE-compliant study demonstrates the high heterogeneity of biological responses under ART in children with frequent passage from 1 category to another over time. Close biological evaluation with access to routine plasma HIV-1 RNA load monitoring is crucial for adapting the complex outcomes of ART in HIV-infected children born from infected mothers.
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http://dx.doi.org/10.1097/MD.0000000000019978DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249904PMC
May 2020

Publisher Correction: M. tuberculosis infection and antigen specific cytokine response in healthcare workers frequently exposed to tuberculosis.

Sci Rep 2019 Oct 23;9(1):15415. Epub 2019 Oct 23.

Unité de Recherche et de Diagnostics Spécialisés, Laboratoire National de Santé Publique/Centre Hospitalier Universitaire Mère Enfant Fondation Jeanne EBORI, Libreville, Gabon.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41598-019-50847-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6811675PMC
October 2019

Increased platelets count in HIV-1 uninfected infants born from HIV-1 infected mothers.

Hematol Rep 2019 Sep 27;11(3):7056. Epub 2019 Sep 27.

Unités de Recherche et de Diagnostics Spécialisés, Laboratoire National de Santé Publique, Libreville, Gabon.

HIV-exposed uninfected infants (HEU) represent a growing population in developing countries including Gabon. Several studies have shown the vulnerability of these infants toward infectious diseases. The aim of the study was to contribute to the global effort to understand how HIVexposure or anti retroviral therapy affects infants' blood elements. We assessed HEU infants' complete blood count using a blood analyzer instrument. Our investigations showed that among the observed clinically relevant hematological abnormalities events, thrombocytosis was the most prevalent clinically relevant hematological abnormality associated with HEU infants'. We showed that HEU infants had significantly higher platelets count than HUinfants. Therefore, higher level of platelets seems to characterize HEU infants when compared to HU infants.
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http://dx.doi.org/10.4081/hr.2019.7056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6775485PMC
September 2019

M. tuberculosis infection and antigen specific cytokine response in healthcare workers frequently exposed to tuberculosis.

Sci Rep 2019 06 3;9(1):8201. Epub 2019 Jun 3.

Unité de Recherche et de Diagnostics Spécialisés, Laboratoire National de Santé Publique/Centre Hospitalier Universitaire Mère Enfant Fondation Jeanne EBORI, Lambaréné, Gabon.

Tuberculosis (TB) is the leading cause of death due to an infectious agent, but only a small fraction of those infected develop the disease. Cytokines are involved in the mediation and regulation of immunity, and their secretion patterns may reflect the infection status. To increase our understanding of immune response to M. tuberculosis infection, we conducted a cross-sectional study investigating M. tuberculosis infection status and comparing the release profiles of cytokines GM-CSF, IFN-γ, IL-1β, IL-10, IL-12 (p70), IL-2, IL-4, IL-5, IL-6, IL-8, TNF-α, in community controls (CCs) and healthy healthcare workers (HCWs) highly exposed to TB. Among HCWs and CCs, the probability of latent M. tuberculosis (LTB) infection was respectively 5.4 (p = 0.002) and 3.4 (p = 0.006) times higher in men than women. The odds ratio of LTB infection was 4 times higher among HCWs in direct contact with active TB patients than other HCW (p = 0.01). Whole blood supernatant cytokine responses to M. tuberculosis antigens showed differential pro-inflammatory responses between HCWs and CCs. CCs had higher IL-1β responses than HCWs (p = 0.002). HCWs had significantly higher IL-8 responses to M. tuberculosis antigens than HCWs (p = 0.003) and CCs (p = 0.015). HCWs showed weak but positive TNF-α responses to M. tuberculosis antigen stimulation compared to CCs (p ≤ 0.015). Looking at T-helper (1 and 2) responses, HCWs and CCs had significantly higher IFN-γ and IL-2 responses compared to HCWs and CCs (p < [0.0001-0.003]). Also, TB antigen induced IL-5 secretion was significantly higher in HCWs and CCs than in non-infected CCs (p < [0.005-0.04]). M. tuberculosis antigen specific responses in HCWs varied based on active TB exposure gradient. HCWs who were highly exposed to active TB (≥3 hours per day) had significantly higher IFN-γ and IL-8 responses (p ≤ 0.02) than HCWs not in direct contact with active TB patients. HCWs working with active TB patients for 5 to 31 years had a significantly enhanced secretion of proinflammatory cytokines (GM-CSF, IFN-γ, IL-1β, IL-2, IL-6, IL-8, IL-12p70, TNF-α) compared to HCWs (p < [0.0001-0.01]). Secretion of anti-inflammatory/Th2 cytokines IL-5 and IL-10 was also higher in HCWs than HCWs. In conclusion, LTBI individuals controlling the M. tuberculosis infection have an enhanced TB specific Th1-cytokines/proinflammatory response combined with selected Th2 type/anti-inflammatory cytokines induction.
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http://dx.doi.org/10.1038/s41598-019-44294-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6547719PMC
June 2019

Global variation in bacterial strains that cause tuberculosis disease: a systematic review and meta-analysis.

BMC Med 2018 10 30;16(1):196. Epub 2018 Oct 30.

Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Ave, Suite 600, Seattle, WA, 98121, USA.

Background: The host, microbial, and environmental factors that contribute to variation in tuberculosis (TB) disease are incompletely understood. Accumulating evidence suggests that one driver of geographic variation in TB disease is the local ecology of mycobacterial genotypes or strains, and there is a need for a comprehensive and systematic synthesis of these data. The objectives of this study were to (1) map the global distribution of genotypes that cause TB disease and (2) examine whether any epidemiologically relevant clinical characteristics were associated with those genotypes.

Methods: We performed a systematic review of PubMed and Scopus to create a comprehensive dataset of human TB molecular epidemiology studies that used representative sampling techniques. The methods were developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We extracted and synthesized data from studies that reported prevalence of bacterial genotypes and from studies that reported clinical characteristics associated with those genotypes.

Results: The results of this study are twofold. First, we identified 206 studies for inclusion in the study, representing over 200,000 bacterial isolates collected over 27 years in 85 countries. We mapped the genotypes and found that, consistent with previously published maps, Euro-American lineage 4 and East Asian lineage 2 strains are widespread, and West African lineages 5 and 6 strains are geographically restricted. Second, 30 studies also reported transmission chains and 4 reported treatment failure associated with genotypes. We performed a meta-analysis and found substantial heterogeneity across studies. However, based on the data available, we found that lineage 2 strains may be associated with increased risk of transmission chains, while lineages 5 and 6 strains may be associated with reduced risk, compared with lineage 4 strains.

Conclusions: This study provides the most comprehensive systematic analysis of the evidence for diversity in bacterial strains that cause TB disease. The results show both geographic and epidemiological differences between strains, which could inform our understanding of the global burden of TB. Our findings also highlight the challenges of collecting the clinical data required to inform TB diagnosis and treatment. We urge future national TB programs and research efforts to prioritize and reinforce clinical data collection in study designs and results dissemination.
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http://dx.doi.org/10.1186/s12916-018-1180-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6206891PMC
October 2018

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

Front Immunol 2018 14;9:222. Epub 2018 Feb 14.

Centre Hospitalier Universitaire Mère-Enfant Fondation Jeanne Ebori (CHUMEFJE), Libreville, Gabon.

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 ( = 4) and the control HU infants tested ( = 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.
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http://dx.doi.org/10.3389/fimmu.2018.00222DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5817973PMC
March 2019

Use of GeneXpert Remnants for Drug Resistance Profiling and Molecular Epidemiology of Tuberculosis in Libreville, Gabon.

J Clin Microbiol 2017 07 26;55(7):2105-2115. Epub 2017 Apr 26.

Unité de Génétique Mycobacterienne, Institut Pasteur, Paris, France.

Multidrug-resistant (MDR) and extensively drug resistant (XDR) strains of pose major problems for global health. The GeneXpert MTB/RIF (Xpert) assay rapidly detects resistance to rifampin (RIF), but for detection of the additional resistance that defines MDR-TB (MDR tuberculosis) and XDR-TB, and for molecular epidemiology, specimen cultures and a biosafe infrastructure are generally required. We sought to determine whether the remnants of sputa prepared for the Xpert assay could be used directly to find mutations associated with drug resistance and to study molecular epidemiology, thus providing precise characterization of MDR-TB cases in countries lacking biosafety level 3 (BSL3) facilities for cultures. After sputa were processed and run on the Xpert instrument, the leftovers of the samples prepared for the Xpert assay were used for PCR amplification and sequencing or for a line probe assay to detect mutations associated with resistance to additional drugs, as well as for molecular epidemiology with spoligotyping and selective mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing. Of 130 sputum samples from Gabon tested with the Xpert assay, 124 yielded interpretable results; 21 (17%) of these were determined to be RIF Amplification and sequencing or a line probe assay of the Xpert remnants confirmed 18/21 samples as MDR, corresponding to 12/116 (9.5%) new and 6/8 (75%) previously treated TB patients. Spoligotyping and MIRU typing with hypervariable loci identified an MDR Beijing strain present in five samples. We conclude that the remnants of samples processed for the Xpert assay can be used in PCRs to find mutations associated with the resistance to the additional drugs that defines MDR and XDR-TB and to study molecular epidemiology without the need for culturing or a biosafe infrastructure.
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http://dx.doi.org/10.1128/JCM.02257-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5483912PMC
July 2017

Cases of Impaired Oxidative Burst in HIV-Exposed Uninfected Infants' Neutrophils-A Pilot Study.

Front Immunol 2017 9;8:262. Epub 2017 Mar 9.

Unités de Recherche et de Diagnostics Spécialisés, Laboratoire National de Santé Publique , Libreville , Gabon.

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.
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http://dx.doi.org/10.3389/fimmu.2017.00262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5343014PMC
March 2017

Blood transfusion, serum ferritin, and iron in hemodialysis patients in Africa.

J Blood Transfus 2015 11;2015:720389. Epub 2015 Jan 11.

Centre National de Transfusion Sanguine (CNTS), Libreville, Gabon ; Unité de Recherche et de Diagnostic Spécialisé/Laboratoire National de Santé Publique (URDS/LNSP), Libreville, Gabon.

Background and Objectives. There is no data analyzing the outcome of blood transfusions and oral iron therapy in patients with kidneys failure in sub-Saharan Africa. The present study aimed to fill that gap and assess the value of ferritin in the diagnosis of iron overload and deficiency. Design. From January to February 2012, we prospectively studied 85 hemodialysis patients (78% of males and 22% of females aged 20 to 79 years) attending the Gabonese National Hemodialysis Centre. Results. Correlation studies showed (a) a strong positive linear relationship between the number of blood transfusions and high serum ferritin in hemodialysis patient (Spearman r : 0.74; P value: 0.0001); (b) a weak association between the number of blood transfusions and serum iron concentrations (Spearman r : 0.32; P value: 0.04); (c) a weak association between serum ferritin and serum iron (Spearman r : 0.32; P value: 0.003). Also, the strength of agreement beyond chance between the levels of ferritin and iron in the serum was poor (κ = 0.14). The prevalence of iron overload was 10.6%, whereas the prevalence of iron deficiency was 2.3%, comparing (1) patients with a maximum of one transfusion not on iron therapy; (2) patients with a maximum of one transfusion on iron therapy; (3) polytransfused patients not on iron therapy; and (4) polytransfused patients on oral iron therapy. The "Kruskal-Wallis test" showed that ferritin levels varied significantly between the groups (P value: 0.0001). Conclusion. Serum ferritin is not reliable as a marker of iron overload. For patients undergoing regular transfusion we recommend routine serum ferritin measurement and yearly measurement of LIC.
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http://dx.doi.org/10.1155/2015/720389DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4306216PMC
February 2015

Antimicrobial profiles of bacterial clinical isolates from the Gabonese National Laboratory of Public Health: data from routine activity.

Int J Infect Dis 2014 Dec 30;29:48-53. Epub 2014 Oct 30.

Unité des Recherche et de Diagnostic Spécialisé, Laboratoire National de Santé Publique, Avenue felix Eboué, Libreville, BP 10736, Gabon. Electronic address:

Background: The present study is one of the first to provide a picture of antimicrobial resistance for a range of bacteria and antimicrobial classes in Gabon, Central Africa.

Methods: During the year 2010, 146 urine cytology, 143 blood cultures, 107 vaginal swabs, 23 urethral swabs, and 18 other culture examinations were positives. All isolates were tested for antibiotic sensitivity.

Results: Four hundred thirty-seven microorganisms were isolated: 210 enterobacteria, 166 staphylococci, 38 streptococci, 14 Acinetobacter, and nine Stenotrophomonas. Of the Klebsiella isolates, 18% and 30% were found to be resistant to selected third-generation cephalosporins (3CG) and fourth-generation cephalosporins (4CG), respectively. Sixty-seven percent of Escherichia coli isolates were resistant to amoxicillin with clavulanic acid. Between 3% and 30% of E. coli isolates were resistant to selected 3CG. All Enterobacter cloacae isolates were sensitive to imipenem. Resistance to quinolones/fluoroquinolones was seen in 21-50% of E. coli isolates. Twenty-six percent of E. cloacae showed resistance to ceftazidime and 37% to cefotaxime. The resistance rate to quinolones ranged between 58% and 78%. Thirty-two percent of Staphylococcus isolates were resistant to gentamicin. Low resistance rates to teicoplanin (2-4%) were observed. Thirty-seven percent of isolated Staphylococcus aureus and 61% of isolated Staphylococcus saprophyticus were resistant to both penicillin G and oxacillin. Streptococcus isolates had low resistance rates to erythromycin, ceftriaxone, and ciprofloxacin (5%, 7%, and 14%, respectively) and were highly resistant to tetracycline, gentamicin, and sulfamethoxazole-trimethoprim (92%, 91%, and 62%, respectively).

Conclusions: The antimicrobial resistance profiles seen here are of concern. To control the spread of drug-resistant bacteria, clinicians should be cognizant of their local antimicrobial resistance patterns.
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http://dx.doi.org/10.1016/j.ijid.2014.01.015DOI Listing
December 2014

Chlamydia trachomatis, human immunodeficiency virus (HIV) distribution and sexual behaviors across gender and age group in an African setting.

PLoS One 2014 3;9(3):e90174. Epub 2014 Mar 3.

Unité de Recherche et de Diagnostic Spécialisé, Laboratoire National de Santé Publique (LNSP) BP 10736, Libreville, Gabon.

Objective: The purpose of this study was to (1) describe the distribution of Chlamydia trachomatis (CT) and Human Immunodeficiency Virus (HIV) cases across gender and age groups in Libreville (Gabon); (2) examine Gabonese Sexually Transmitted Infections (STIs)-related risk behaviour.

Methods: The sampled population was people attending the "Laboratoire National de Santé Plublique". Between 2007 and 2011, 14 667 and 9 542 people respectively, were tested for CT and HIV infections. 1 854 of them were tested for both infections. We calculated CT and HIV rates across gender and age groups. Also analysed was the groups' contribution to the general CT and HIV epidemiology. STIs-related risk behaviours were assessed in 224 men and 795 women (between July 2011 and March 2013) who agreed and answered a questionnaire including questions on their marital status, number of sex partners, sexual practices, history of STIs, sex frequency and condom use.

Results: Data showed a 24% dropped in the CT infection rate between 2007 and 2010, followed by a 14% increase in 2011. The HIV infection rates for the same period were between 15% and 16%. The risk of a CT-positive subject getting HIV is about 0.71 times the risk of a CT-negative subject. Young adult aged between 18 and 35 years old represented 65.2% of people who had STIs. 80% of women and 66% of men confessed to an inconsistent use of condoms. 11.6% of women and 48% of men declared having multiple sex partners. 61% of questioned women and 67% of men declared knowing their HIV status.

Conclusions: In this Gabonese setting, the population-aged from 18 to 35 years is the most affected by STIs. Other matters of concern are the inconsistent use of protection and sex with non-spousal or non-life partners.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0090174PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3940824PMC
January 2015

Differential cytokine/chemokines and KL-6 profiles in patients with different forms of tuberculosis.

Cytokine 2009 Aug 30;47(2):132-6. Epub 2009 Jun 30.

Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences/MRC Centre for Molecular and Cellular Biology/DST and NRF Centre of Excellence for Biomedical TB Research, Stellenbosch University, South Africa.

Cytokines are involved in the mediation and regulation of immunity, inflammation, and haematopoiesis. Secretion patterns may reflect the pathology or etiology of different diseases. In an attempt to increase our understanding of immunopathology during different forms of tuberculosis, and identify potential biological markers that may differentiate between forms of tuberculosis, we investigated the levels of 29 cytokines and KL-6 in the plasma of HIV uninfected patients with active pulmonary tuberculosis (TB) without pleural effusions and in pleural TB with and without HIV-co-infection. Healthy individuals with latent Mycobacterium tuberculosis infection and patients with non-TB pleural effusions were used as controls, We showed that pleural TB patients had increased levels of markers associated with systemic inflammation compared to pulmonary TB (EGF, G-CSF, IL-1beta IL-6, IL-8, IL-10, MCP-1, MIP-1alpha, MIP-1beta, TNF-alpha and VEGF), whereas pulmonary TB patients without effusions had higher levels of factors involved in cell-mediated immunity (IL-12p40 and sCD40L). Plasma levels of cytokines may therefore contribute to biosignatures of diseases like TB but the data also highlight systemic differences between pulmonary TB, pleural TB and other form of pleural effusion diseases.
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http://dx.doi.org/10.1016/j.cyto.2009.05.016DOI Listing
August 2009

Biomarkers for TB treatment response: challenges and future strategies.

J Infect 2008 Aug 22;57(2):103-9. Epub 2008 Jul 22.

NRF/DST Centre of Excellence for TB Biomedical Research, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, South Africa.

Currently the ultimate success of anti-TB therapy is measured by the relapse rate within the first 2 years after treatment. The long duration of clinical trials that rely on this outcome constitute a disincentive for the pharmaceutical industry to develop new TB drugs. Biomarkers for relapse measurable during early treatment may shorten clinical trials. Additionally pre-treatment markers could allow stratification of patients into groups with different treatment requirements for improved clinical management. Currently there is a lack of sufficiently validated biomarkers with good individual predictive value and an urgent need for candidate markers and their evaluation in prospective studies. This review provides an overview of novel biomarkers for TB treatment response and outcome focusing on immunological markers in serum. Additionally, the challenges and roadblocks biomarker research is currently faced with are highlighted.
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http://dx.doi.org/10.1016/j.jinf.2008.06.007DOI Listing
August 2008

An evaluation of commercial fluorescent bead-based luminex cytokine assays.

PLoS One 2008 Jul 2;3(7):e2535. Epub 2008 Jul 2.

Department of Biomedical Sciences, Division of Molecular Biology and Human Genetics, Stellenbosch University Cape-Town, Stellenbosch, South Africa.

The recent introduction of fluorescent bead-based technology, allowing the measurement of multiples analytes in a single 25-50 microl sample has revolutionized the study of cytokine responses. However, such multiplex approaches may compromise the ability of these assays to accurately measure actual cytokine levels. This study evaluates the performance of three commercially available multiplex cytokine fluorescent bead-based immunoassays (Bio-Rad's Cytokine 17-plex kit; LINCO Inc's 29-plex kit; and RnD System's Fluorokine-Multi Analyte Profiling (MAP) base kit A and B). The LINCO Inc kit was found to be the most sensitive assay for measuring concentrations of multiple recombinant cytokines in samples that had been spiked with serial dilutions of the standard provided by the manufacturer, followed respectively by the RnD Fluorokine-(MAP) and Bio-Rad 17-plex kits. A positive correlation was found in the levels of IFN-gamma measured in antigen stimulated whole blood culture supernatants by the LINCO Inc 29-plex, RnD Fluorokine-(MAP) and RnD system IFN-gamma Quantikine ELISA kits across a panel of controls and stimulated samples. Researchers should take the limitation of such multiplexed assays into account when planning experiments and the most appropriate use for these tests may currently be as screening tools for the selection of promising markers for analysis by more sensitive techniques.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0002535PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2432042PMC
July 2008

Differential expression of interleukin-4 (IL-4) and IL-4 delta 2 mRNA, but not transforming growth factor beta (TGF-beta), TGF-beta RII, Foxp3, gamma interferon, T-bet, or GATA-3 mRNA, in patients with fast and slow responses to antituberculosis treatment.

Clin Vaccine Immunol 2008 Aug 25;15(8):1165-70. Epub 2008 Jun 25.

Division of Molecular Biology and Human Genetics, MRC Centre for Molecular and Cellular Biology, DST and NRF Centre of Excellence for Biomedical TB Research, Stellenbosch University, Cape Town 7505, South Africa.

This study investigated interleukin-4 (IL-4), IL-4 delta 2, transforming growth factor beta (TGF-beta), TGF-beta RII, Foxp3, GATA-3, T-bet, and gamma interferon (IFN-gamma) transcription in peripheral blood samples of adult pulmonary tuberculosis patients prior to and after 1 week of therapy. Twenty patients with positive results for sputum culture for Mycobacterium tuberculosis were enrolled and treated with directly observed short-course antituberculosis chemotherapy. Early treatment response was assessed. At the end of the intensive phase of treatment (month 2), 12 patients remained sputum culture positive (slow responders) and 8 converted to a negative culture (fast responders). Only the expression levels of IL-4 (4-fold decrease) and IL-4 delta 2 (32-fold increase) changed significantly during the first week of therapy in the 20 patients. No baseline differences were present between the responder groups, but fast responders had significantly higher IL-4 transcripts than slow responders at week 1. Fast responders showed a 19-fold upregulation and slow responders a 47-fold upregulation of IL-4 delta 2 at week 1. Only slow responders also showed a significant decrease in IL-4 expression at week 1. There were no significant differences in expression of TGF-beta, TGF-beta RII, Foxp3, IFN-gamma, and GATA-3 between the groups. These data show that differential IL-4-related gene expression in the early stage of antituberculosis treatment accompanies differential treatment responses and may hold promise as a marker for treatment effect.
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http://dx.doi.org/10.1128/CVI.00084-08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2519297PMC
August 2008

Immune parameters as markers of tuberculosis extent of disease and early prediction of anti-tuberculosis chemotherapy response.

J Infect 2008 May 21;56(5):340-7. Epub 2008 Mar 21.

Department of Biomedical Sciences, Division of Molecular Biology and Human Genetics, Faculty of Health Sciences, Stellenbosch University, Cape Town, Western Cape, 7505 South Africa.

This study investigates how the extent of pre-treatment radiological disease and early anti-tuberculous treatment response affect levels of selected circulating host immune markers. Twenty HIV-uninfected tuberculosis patients with BACTEC culture positivity for Mycobacterium tuberculosis at diagnosis and treated with directly observed short course anti-tuberculosis chemotherapy and 13 healthy community controls were enrolled. Serum samples were collected throughout treatment. After the intensive phase of treatment, 12 patients remained sputum culture-positive (slow responders) and eight patients were culture negative (fast responders). C-reactive protein (CRP), soluble intercellular adhesion molecule-1 (sICAM-1), soluble urokinase plasminogen activator receptor (suPAR), soluble lymphocyte activation gene-3 (sLAG-3), granzyme B, soluble tumour necrosis factor receptor one and two (sTNFR I and sTNFR II) and soluble death receptor 5 (sDR5) concentrations were measured. High levels of CRP at diagnosis were found to be associated (p
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http://dx.doi.org/10.1016/j.jinf.2008.02.007DOI Listing
May 2008

Correlates for disease progression and prognosis during concurrent HIV/TB infection.

Int J Infect Dis 2007 Jul 18;11(4):289-99. Epub 2007 Apr 18.

Immunology Unit, Department of Biomedical Sciences, DST/NRF Center of Excellence in Biomedical TB Research, Faculty of Health Sciences, University of Stellenbosch, PO Box 19063, Tygerberg 7505, South Africa.

Mycobacterium tuberculosis (Mtb) and the human immunodeficiency virus (HIV) are both life-threatening pathogens in their own right, but their synergic effects on the immune system during co-infection markedly enhance their effect on the host. This review focuses on the bidirectional interaction between HIV and Mtb and discusses the relevance of sputum smear examination, CD4+ counts, viral load at baseline and after initiation of anti-retroviral therapy, as well as additional existing and new potential immune correlates of disease progression and prognosis. These markers include beta2-microglobulin, neopterin, tumor necrosis factor receptor II (TNFRII), CD8+/CD38+, soluble urokinase plasminogen activator receptor (suPAR) and CXCL10 (or IP-10).
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http://dx.doi.org/10.1016/j.ijid.2007.02.001DOI Listing
July 2007