Genome-wide association study of leprosy in Malawi and Mali.

Leprosy is a chronic infection of the skin and peripheral nerves caused by Mycobacterium leprae. Despite recent improvements in disease control, leprosy remains an important cause of infectious disability globally. Large-scale genetic association studies in Chinese, Vietnamese and Indian populations have identified over 30 susceptibility loci for leprosy. There is a significant burden of leprosy in Africa, however it is uncertain whether the findings of published genetic association studies are generalizable to African populations. To address this, we conducted a genome-wide association study (GWAS) of leprosy in Malawian (327 cases, 436 controls) and Malian (247 cases, 368 controls) individuals. In that analysis, we replicated four risk loci previously reported in China, Vietnam and India; MHC Class I and II, LACC1 and SLC29A3. We further identified a novel leprosy susceptibility locus at 10q24 (rs2015583; combined p = 8.81 × 10-9; OR = 0.51 [95% CI 0.40 - 0.64]). Using publicly-available data we characterise regulatory activity at this locus, identifying ACTR1A as a candidate mediator of leprosy risk. This locus shows evidence of recent positive selection and demonstrates pleiotropy with established risk loci for inflammatory bowel disease and childhood-onset asthma. A shared genetic architecture for leprosy and inflammatory bowel disease has been previously described. We expand on this, strengthening the hypothesis that selection pressure driven by leprosy has shaped the evolution of autoimmune and atopic disease in modern populations. More broadly, our data highlights the importance of defining the genetic architecture of disease across genetically diverse populations, and that disease insights derived from GWAS in one population may not translate to all affected populations.

Description of Acinetobacter ihumii sp. nov., Microbacterium ihumii sp. nov., and Gulosibacter massiliensis sp. nov., three new bacteria isolated from human blood.

Blood is precious tissue that is normally sterile. With the aim of diagnosing the cause of bacteremia, three bacterial strains were isolated from three different individuals. Strains Marseille-P7157T and Marseille-Q2854T are Gram-stain positive, non-spore-forming rod-shaped bacteria, while strain Marseille-P8049T is a Gram-stain negative, motile, non-spore-forming and rod-shaped bacterium. The major fatty acids found (>30%) were hexadecanoic acid for strain Marseille-P8049T and 12-methyl tetradecanoic acid for both strains Marseille-P7157T and Marseille-P2854T. The 16S rRNA gene sequence analysis shows that strains Marseille-P8049 and Marseille-Q2854T have sequence similarity of 96.8%, 99.04%, and 98.3% with Acinetobacter ursingii strain LUH3792 (NR_025392.1), Gulosibacter faecalis strain B187 (NR_041812.1), and Schaalia canis strain CCUG 41706 (NR_025366.1), respectively. In addition, strains Marseille-Q2854T, Marseille-P8049T and Marseille-P7157T shared with their closely related species cited above the following DDH values: 19.5%, 24.4%, and 20.2%, respectively. Based on these phenotypic and genomic findings, we consider that strains Marseille-P8049T (= CSUR P8049 = CECT 30350), Marseille-P2854T ( = CSUR Q2854 = CECT 30120) and Marseille-P7157T ( = CSUR P7157 = CECT 30048) are new bacterial species, for which the names Acinetobacter ihumii sp. nov., Microbacterium ihumii sp. nov., and Gulosibacter massiliensis sp. nov., are proposed.

Effect of Seasonal Malaria Chemoprevention on Immune Markers of Exhaustion and Regulation.

BACKGROUND: Seasonal malaria chemoprevention (SMC) is a novel strategy to reduce malaria infections in children. Infection with Plasmodium falciparum results in immune dysfunction characterized by elevated expression of markers associated with exhaustion, such as PD1 and LAG3, and regulatory CD4+FOXP3+ T cells. METHODS: In the current study, the impact of seasonal malaria chemoprevention on malaria-induced immune dysfunction, as measured by markers associated with exhaustion and regulatory T cells, was explored by flow cytometry. RESULTS: Children that received seasonal malaria chemoprevention had fewer malaria episodes and showed significantly lower fold changes in CD4+PD1+ and CD4+PD1+LAG3+ compared to those that did not receive SMC. Seasonal malaria chemoprevention had no observable effect on fold changes in CD8 T cells expressing PD1 or CD160. However, children receiving SMC showed greater increases in CD4+FOXP3+ T regulatory cells compared to children not receiving SMC. CONCLUSIONS: These results provide important insights into the dynamics of malaria-induced changes in the CD4 T-cell compartment of the immune system and suggest that the reduction of infections due to seasonal malaria chemoprevention may also prevent immune dysfunction. CLINICAL TRIALS REGISTRATION: NCT02504918.

Efficacy of artemether-lumefantrine in relation to drug exposure in children with and without severe acute malnutrition: an open comparative intervention study in Mali and Niger.

BACKGROUND: Severe acute malnutrition (SAM) affects almost all organs and has been associated with reduced intestinal absorption of medicines. However, very limited information is available on the pharmacokinetic properties of antimalarial drugs in this vulnerable population. We assessed artemether-lumefantrine (AL) clinical efficacy in children with SAM compared to those without. METHODS: Children under 5 years of age with uncomplicated P. falciparum malaria were enrolled between November 2013 and January 2015 in Mali and Niger, one third with uncomplicated SAM and two thirds without. AL was administered under direct observation with a fat intake consisting of ready-to-use therapeutic food (RUTF - Plumpy'Nut®) in SAM children, twice daily during 3 days. Children were followed for 42 days, with PCR-corrected adequate clinical and parasitological response (ACPR) at day 28 as the primary outcome. Lumefantrine concentrations were assessed in a subset of participants at different time points, including systematic measurements on day 7. RESULTS: A total of 399 children (360 in Mali and 39 in Niger) were enrolled. Children with SAM were younger than their non-SAM counterparts (mean 17 vs. 28 months, P < 0.0001). PCR-corrected ACPR was 100 % (95 % CI, 96.8-100 %) in SAM at both day 28 and 42, versus 98.8 % (96.4-99.7 %) at day 28 and 98.3 % (95.6-99.4 %) at day 42 in non-SAM (P = 0.236 and 0.168, respectively). Compared to younger children, children older than 21 months experienced more reinfections and SAM was associated with a greater risk of reinfection until day 28 (adjusted hazard ratio = 2.10 (1.04-4.22), P = 0.038). Day 7 lumefantrine concentrations were significantly lower in SAM than non-SAM (median 251 vs. 365 ng/mL, P = 0.049). CONCLUSIONS: This study shows comparable therapeutic efficacy of AL in children without SAM and in those with SAM when given in combination with RUTF, but a higher risk of reinfection in older children suffering from SAM. This could be associated with poorer exposure to the antimalarials as documented by a lower lumefantrine concentration on day 7. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01958905 , registration date: October 7, 2013.

Protection of Malian children from clinical malaria is associated with recognition of multiple antigens.

BACKGROUND: Naturally acquired immunity to clinical malaria is thought to be mainly antibody-mediated, but reports on antigen targets are contradictory. Recognition of multiple antigens may be crucial for protection. In this study, the magnitude of antibody responses and their temporal stability was assessed for a panel of malaria antigens in relation to protection against clinical Plasmodium falciparum malaria. METHODS: Malian children aged two to 14 years were enrolled in a longitudinal study and followed up by passive and active case detection for seven months. Plasma was collected at enrolment and at the beginning, in the middle and after the end of the transmission season. Antibody titres to the P. falciparum-antigens apical membrane protein (AMA)-1, merozoite surface protein (MSP)-119, MSP-3, glutamine-rich protein (GLURP-R0) and circumsporozoite antigen (CSP) were assessed by enzyme-linked immunosorbent assay (ELISA) for 99 children with plasma available at all time points. Parasite carriage was determined by microscopy and nested PCR. RESULTS: Antibody titres to all antigens, except MSP-119, and the number of antigens recognized increased with age. After malaria exposure, antibody titres increased in children that had low titres at baseline, but decreased in those with high baseline responses. No significant differences were found between antibody titers for individual antigens between children remaining symptomatic or asymptomatic after exposure, after adjustment for age. Instead, children remaining asymptomatic following parasite exposure had a broader repertoire of antigen recognition. CONCLUSIONS: The present study provides immune-epidemiological evidence from a limited cohort of Malian children that strong recognition of multiple antigens, rather than antibody titres for individual antigens, is associated with protection from clinical malaria.

Plasmodium vivax malaria in Mali: a study from three different regions.

BACKGROUND: Plasmodium vivax has traditionally been considered virtually absent from Western and Central Africa, due to the absence of the Duffy blood group in most of the population living in these areas. Recent reports, however, suggest the circulation of P. vivax in sub-Saharan Africa. METHODS: Giemsa/Field-stained smears from febrile patients recruited in five different cities (Goundam, Tombouctou, Gao, Bourem and Kidal) pertaining to three regions from Northern Mali were examined. Nested-PCR and DNA sequence analyses of selected samples were performed to fully confirm the presence of P. vivax infections. RESULTS: Results demonstrated the presence of P. vivax infections in close to 30% of the cases as detected by Giemsa/Field-stained smears and nested-PCR and DNA-sequence analyses of selected samples unequivocally confirmed the presence of P. vivax. CONCLUSIONS: The diagnostics of this human malaria parasite should be taken into account in the context of malaria control and elimination efforts, not only in Mali, but also in sub-Saharan Africa.

Candidate polymorphisms and severe malaria in a Malian population.

Malaria is a major health burden in sub-Saharan African countries, including Mali. The disease is complex, with multiple genetic determinants influencing the observed variation in response to infection, progression, and severity. We assess the influence of sixty-four candidate loci, including the sickle cell polymorphism (HbS), on severe malaria in a case-control study consisting of over 900 individuals from Bamako, Mali. We confirm the known protective effects of the blood group O and the HbS AS genotype on life-threatening malaria. In addition, our analysis revealed a marginal susceptibility effect for the CD40 ligand (CD40L)+220C allele. The lack of statistical evidence for other candidates may demonstrate the need for large-scale genome-wide association studies in malaria to discover new polymorphisms. It also demonstrates the need for establishing the region-specific repertoire of functional variation in important genes, including the glucose-6-phosphatase deficiency gene, before embarking on focused genotyping.

Safety of epoietin beta-quinine drug combination in children with cerebral malaria in Mali.

BACKGROUND: Cerebral malaria carries an unacceptable case fatality rate in children despite timely and adequate chemotherapy. To improve the survival rate, adjunctive therapies previously tested mainly focused on the modulation of the inflammatory response, without definitive effect in humans. In this context, a new adjunctive strategy using a neuroprotective drug: erythropoietin (epoietin-beta, Epo) was proposed. METHODS: An open-labelled study including cerebral malaria children (Blantyre coma score below 3) was conducted in Mali. The objective was to assess the short-term safety (seven days) of erythropoietin at high doses (1,500 U/kg/day during three days) combined to quinine. RESULTS: 35 patients with unrousable coma were included in the study. None of expected side effects of erythropoietin were observed during the seven days follow-up. No significant increase in the case fatality rate (7/35 patients) was observed compared to other studies with mortality rates ranging from 16 to 22% in similar endemic areas. CONCLUSION: These data provide the first evidence of the short-term safety of erythropoietin at high doses combined to quinine. A multicentre study is needed to assess the potential of Epo as an adjunctive therapy to increase the survival during cerebral malaria. CLINICAL REGISTRATION NUMBER: ClinicalTrials.gov ID: NCT00697164.

A functional promoter variant in IL12B predisposes to cerebral malaria.

The role of the Th1 pathway in the pathogenesis of severe malaria is unclear. We recently reported that a polymorphism with increasing IFNG transcription is associated with protection against cerebral malaria (CM). Interleukin-12 is required for Th1 cell differentiation, which is characterized by the production of interferon-gamma. We investigated 21 markers in IL12-related genes, including IL12A and IL12B encoding the two IL-12 (IL12p70) subunits, IL12p35 and IL12p40. We performed a family-based association study using a total sample set of 240 nuclear families. The IL12Bpro polymorphism was associated with susceptibility to CM. The CTCTAA allele and the GC/CTCTAA genotype are over-transmitted to children with CM (P = 0.0002 and 0.00002, respectively). We estimated the odds ratio to be 2.11 for risk of CM in heterozygous children [(95% confidence interval, 1.49-2.99); P < 0.0001]. Although the CTCTAA allele had a dominant effect on CM susceptibility, this effect is much stronger in heterozygous children, consistent with the functional effects of this allele in a heterozygous form. Heterozygosity for this polymorphism has been associated with reduced expression of the gene encoding IL12p40 and a low level of IL12p70 production. These results, together with the findings from immunological studies of low interferon-gamma and IL-12 levels in CM, support a protective role for the Th1 pathway in CM.