Molecular Mechanism of Heme Acquisition and Degradation by the Human Pathogen Group A Streptococcus

Heme is the major iron source for the deadly human pathogen, Group A Streptococcus (GAS). During infection, GAS lyses host cells releasing hemoglobin and other hemoproteins. This dissertation aims to elucidate the general mechanism by which GAS obtains and utilizes heme as an iron source from the host hemoproteins. GAS encodes a heme relay system consisting of Shr, Shp and the SiaABC transporter. We specifically determine the role of Shr in the heme uptake process, by conducting a detailed functional characterization of its constituent domains. We also undertake to solve the long-standing mystery surrounding the catabolism of heme in streptococci. The studies presented herein established Shr as a prototype of a new family of NEAT-containing hemoproteins receptors. They demonstrate its importance in heme acquisition by GAS and provide a molecular model for heme scavenging and transfer by the protein. We show that Shr modulates heme uptake depending on heme availability by a mechanism where NEAT1 facilitates fast heme scavenging and delivery to Shp, whereas NEAT2 serves as a temporary storage for heme on the bacterial surface. Finally, we identified and characterized for the first time, a heme oxygenase (HO) in the Streptococcus genus which was named HupZ. Sequence comparison between HupZ and several HOs from different structural families indicates that this enzyme is unrelated to any of the previously characterized HOs. However, orthologs of the protein are found in other important pathogens. The structure and the catalytic mechanism of HupZ suggest that it is the representative of a new family of flavoenzymes capable of degrading heme using their reduced flavin cofactor as a source of electrons. Overall, this work contributes significant knowledge to the topic of heme utilization by pathogens and importantly, provides new direct evidence that associates flavins with heme metabolism in bacteria. Thus it sets a new direction in the field and lays the ground for future fundamental and applied discoveries

Dynamics of germs responsible for acute bacterial meningitis in Burkina Faso in the last ten years (2005-2014)

The aim of this study was to analyze ten (10) years of epidemiological surveillance data of meningitis in Burkina Faso for high risk germs patterns identification in order to contribute to the strengthening of prevention strategies.A retrospective study of the past decade (2005- 2014) of cases of acute bacterial meningitis occurred in the thirteen health regions, collected through epidemiological surveillance data meningitis in Burkina Faso. From a total of 88 057 suspected cases of acute bacterial meningitis, we recorded 9134 deaths. From the laboratory confirmed cases, the identified germs were as follows: 56.79% of Neisseria meningitidis, 41.09% of Streptococcus pneumoniae and 2.13% of Haemophilus influenzae. Among the meningococcus isolated, we observed the following distribution: 23.11% of NmA, 58.84% of NmW and 18% of NmX.Mortality associated with acute bacterial meningitis remains still high in Burkina Faso despite the complete disappearance of NmA since 2012, after the conjugate vaccine A (MenAfriVac) has been introduced in this country. However the emergence of NmX, the reemergence of NmW and the persistence of high prevalence of Streptococcus pneumoniae are a major concern in the fight against meningitis in Burkina Faso. So, it is necessary, in addition to the strengthening of surveillance, diagnosis and case management to develop and make available and accessible a conjugate trivalent vaccine against NmA the NmX and NmW serogroups.Keywords: meningococcal meningitis, W and X serogroups, Streptococcus pneumoniae, MenAfriVa

The Global Landscape of Pediatric Bacterial Meningitis Data Reported to the World Health Organization-Coordinated Invasive Bacterial Vaccine-Preventable Disease Surveillance Network, 2014-2019.

BACKGROUND: The World Health Organization (WHO) coordinates the Global Invasive Bacterial Vaccine-Preventable Diseases (IB-VPD) Surveillance Network to support vaccine introduction decisions and use. The network was established to strengthen surveillance and laboratory confirmation of meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis. METHODS: Sentinel hospitals report cases of children 137 000 suspected meningitis cases were reported by 58 participating countries, with 44.6% (n = 61 386) reported from countries in the WHO African Region. More than half (56.6%, n = 77 873) were among children <1 year of age, and 4.0% (n = 4010) died among those with reported disease outcome. Among suspected meningitis cases, 8.6% (n = 11 798) were classified as probable bacterial meningitis. One of 3 bacterial pathogens was identified in 30.3% (n = 3576) of these cases, namely S. pneumoniae (n = 2177 [60.9%]), H. influenzae (n = 633 [17.7%]), and N. meningitidis (n = 766 [21.4%]). Among confirmed bacterial meningitis cases with outcome reported, 11.0% died; case fatality ratio varied by pathogen (S. pneumoniae, 12.2%; H. influenzae, 6.1%; N. meningitidis, 11.0%). Among the 277 children who died with confirmed bacterial meningitis, 189 (68.2%) had confirmed S. pneumoniae. The proportion of pneumococcal cases with pneumococcal conjugate vaccine (PCV) serotypes decreased as the number of countries implementing PCV increased, from 77.8% (n = 273) to 47.5% (n = 248). Of 397 H. influenzae specimens serotyped, 49.1% (n = 195) were type b. Predominant N. meningitidis serogroups varied by region. CONCLUSIONS: This multitier, global surveillance network has supported countries in detecting and serotyping the 3 principal invasive bacterial pathogens that cause pediatric meningitis. Streptococcus pneumoniae was the most common bacterial pathogen detected globally despite the growing number of countries that have nationally introduced PCV. The large proportions of deaths due to S. pneumoniae reflect the high proportion of meningitis cases caused by this pathogen. This global network demonstrated a strong correlation between PCV introduction status and reduction in the proportion of pneumococcal meningitis infections caused by vaccine serotypes. Maintaining case-based, active surveillance with laboratory confirmation for prioritized vaccine-preventable diseases remains a critical component of the global agenda in public health.The World Health Organization (WHO)-coordinated Invasive Bacterial Vaccine-Preventable Disease (IB-VPD) Surveillance Network reported data from 2014 to 2019, contributing to the estimates of the disease burden and serotypes of pediatric meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis

A Foreign Protein Incorporated on the Tip of T3 Pili in Lactococcus lactis Elicits Systemic and Mucosal Immunity▿ †

The use of Lactococcus lactis to deliver a chosen antigen to the mucosal surface has been shown to elicit an immune response in mice and is a possible method of vaccination in humans. The recent discovery on Gram-positive bacteria of pili that are covalently attached to the bacterial surface and the elucidation of the residues linking the major and minor subunits of such pili suggests that the presentation of an antigen on the tip of pili external to the surface of L. lactis might constitute a successful vaccine strategy. As a proof of principle, we have fused a foreign protein (the Escherichia coli maltose-binding protein) to the C-terminal region of the native tip protein (Cpa) of the T3 pilus derived from Streptococcus pyogenes and expressed this fusion protein (MBP*) in L. lactis. We find that MBP* is incorporated into pili in this foreign host, as shown by Western blot analyses of cell wall proteins and by immunogold electron microscopy. Furthermore, since the MBP* on these pili retains its native biological activity, it appears to retain its native structure. Mucosal immunization of mice with this L. lactis strain expressing pilus-linked MBP* results in production of both a systemic and a mucosal response (IgG and IgA antibodies) against the MBP antigen. We suggest that this type of mucosal vaccine delivery system, which we term UPTOP (for unhindered presentation on tips of pili), may provide an inexpensive and stable alternative to current mechanisms of immunization for many serious human pathogens

Triplex real-time PCR assay for the detection of Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae directly from clinical specimens without extraction of DNA

International audienceThis study presents a triplex real-time PCR assay that allows for the direct detection of Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae in one reaction without DNA extraction, with similar sensitivity and specificity to singleplex assays. This approach saves time, specimen volume and reagents while achieving a higher testing throughput

Recherche-action en partenariat et innovations face aux changements globaux en Afrique subsaharienne

National audienceLes paysans de l'Afrique subsaharienne doivent innover pour accroitre durablement la production agricole, pour contribuer à la sécurité alimentaire et pour s'adapter aux changements globaux (climatiques, démographiques, etc.). Mais force est de reconnaitre que la majorité des modèles de changement proposés par la recherche n'ont pas été adoptés par les paysans. L'une des raisons invoquée est leur manque d'implication active dans les processus de recherche. La Recherche Action en Partenariat (RAP) vise à remédier à cette insuffisance. Cette communication présente les principes et les dispositifs méthodologique de la RAP en s'appuyant sur le projet Fertipartenaires (Food/2007/144/075, 2008 à 2012). L'objectif du projet était de co-construire des innovations visant à relever la fertilité du sol en appliquant une démarche de RAP. La RAP s'appuie sur des plateformes d'innovations villageoises (Comité de Concertation Villageois, CCV) et se déroule en 4 phases (diagnostics, élaboration de solutions, actions, évaluation des résultats et impacts). Les CCV sont des associations de groupements paysans permettant d'enrôler les agriculteurs et éleveurs dans toutes les phases de la co-construction de l'innovation. La phase de diagnostic a permis de dresser un état des lieux des systèmes de production. La phase d'exploration des solutions a nécessité la mise en oeuvre de formations et de voyages à destination des membres des CCV. La phase de mise en oeuvre a permis d'expérimenter des innovations techniques (1 600 fosses fumières/compostières, 600 expérimentations de techniques culturales innovantes) et organisationnelle (1 charte foncière locale communale). La phase d'évaluation a permis d'estimer l'impact du projet sur les connaissances acquises, les changements de pratiques, leurs effets et leur diffusion. En favorisant l'échange et l'hybridation des connaissances entre paysans, acteurs de l'environnement des exploitations et chercheurs, la RAP renforce les capacités d'innovations et d'adaptation des acteurs face aux changements globaux

Seroprevalence of human immunodefi ciency virus, hepatitis B and C viruses and syphilis among blood donors in Koudougou (Burkina Faso) in 2009

Background. The high prevalence of numerous transfusion-transmitted infectious diseases such as human immunodefi ciency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) and syphilis in sub-Saharan Africa affects the safety of blood for recipients. This study was undertaken with the aim of determining the seroprevalence of HIV, HCV, HBV, syphilis and socio-demographic risk factors associated with blood donation in a new regional blood transfusion centre in Burkina Faso. Material and methods. Sera samples were screened for hepatitis B surface antigen (HBsAg), antibodies to HCV, HIV types 1 and 2 and to Treponema pallidum using enzymelinked immunosorbent assays and Rapid Plasma Reagin test (RPR) respectively. All the reactive samples for HIV, HBsAg, and HCV were confi rmed using a second enzyme-linked immunosorbent assays. Antibodies to Treponema pallidum were confi rmed with a Treponema pallidum haemagglutination test (TPHA). Results. From the total of 4,520 blood donors in 2009, 1,348 (29.82%) were infected with at least one pathogen and 149 (3.30%) had serological evidence of multiple infections. The overall seroprevalence rate of HIV, HBV, HCV and syphilis was 2.21%, 14.96%, 8.69% and 3.96%, respectively. Among blood donors with multiples infections, the most common dual or triple combinations were HBsAg-HCV (1.39%), HBsAg-syphilis (0.66%) and HBsAg-HCV-syphilis (0.11%). The highest prevalences of HBsAg and HIV were found among blood donors from rural areas and in the age groups of 20-29 years and &gt;40 years old, respectively. Conclusion. HBV and HCV remain the greatest threats to blood safety in Burkina Faso. Strict selection and retention of voluntary, non-remunerated low-risk blood donors are recommended to improve blood safety in the regional blood transfusion centre of Koudougou