Complex genetic control of susceptibility to malaria: positional cloning of the Char9 locus

Mouse strains AcB55 and AcB61 are resistant to malaria by virtue of a mutation in erythrocyte pyruvate kinase (PklrI90N). Linkage analysis in [AcB55 × A/J] F2 mice detected a second locus (Char9; logarithm of odds = 4.74) that regulates the blood-stage replication of Plasmodium chabaudi AS independently of Pklr. We characterized the 77 genes of the Char9 locus for tissue-specific expression, strain-specific alterations in gene expression, and polymorphic variants that are possibly associated with differential susceptibility. We identified Vnn1/Vnn3 as the likely candidates responsible for Char9. Vnn3/Vnn1 map within a conserved haplotype block and show expression levels that are strictly cis-regulated by this haplotype. The absence of Vnn messenger RNA expression and lack of pantetheinase protein activity in tissues are associated with susceptibility to malaria and are linked to a complex rearrangement in the Vnn3 promoter region. The A/J strain also carries a unique nonsense mutation that leads to a truncated protein. Vanin genes code for a pantetheinase involved in the production of cysteamine, a key regulator of host responses to inflammatory stimuli. Administration of cystamine in vivo partially corrects susceptibility to malaria in A/J mice, as measured by reduced blood parasitemia and decreased mortality. These studies suggest that pantetheinase is critical for the host response to malaria

Drug Delivery by Tattooing to Treat Cutaneous Leishmaniasis

This study establishes a proof-of-concept that a tattoo device can target intra-dermal drug delivery against cutaneous leishmaniasis (CL). the selected drug is oleylphosphocholine (OlPC) formulated as liposomes, particles known to be prone to macrophage ingestion. We first show that treatment of cultured Leishmania-infected macrophages with OlPC-liposomes results in a direct dose-dependent killing of intracellular parasites. Based on this, in vivo efficacy is demonstrated using a 10 day tattooing-mediated treatment in mice infected with L. major and L. mexicana. in both models this regimen results in rapid clinical recovery with complete regression of skin lesions by Day 28. Parasite counts and histopathology examination confirm high treatment efficacy at the parasitic level. Low amount of drug required for tattooing combined with fast clinical recovery may have a positive impact on CL patient management. This first example of tattoo-mediated drug delivery could open to new therapeutic interventions in the treatment of skin diseases.Rising stars in Global healthGrand Challenges CanadaMcGill Univ, Fac Med, Ctr Hlth, Dept Med,Res Inst, Montreal, PQ, CanadaMcGill Univ, Fac Med, Ctr Hlth, Dept Microbiol & Immunol,Res Inst, Montreal, PQ, CanadaUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilUniv Montreal, Fac Med Vet, Dept Pathol & Microbiol, St Hyacinthe, PQ J2S 7C6, CanadaDafra Pharma Res & Dev, Turnhout, BelgiumMT Derm, Berlin, GermanyMcGill Univ, Dept Biochem, Montreal, PQ, CanadaUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilRising stars in Global health: 0015-01-04-01-01Web of Scienc

Identification of Loci Controlling Restriction of Parasite Growth in Experimental Taenia crassiceps Cysticercosis

Human neurocysticercosis (NC) caused by Taenia solium is a parasitic disease of the central nervous system that is endemic in many developing countries. In this study, a genetic approach using the murine intraperitoneal cysticercosis caused by the related cestode Taenia crassiceps was employed to identify host factors that regulate the establishment and proliferation of the parasite. A/J mice are permissive to T. crassiceps infection while C57BL/6J mice (B6) are comparatively restrictive, with a 10-fold difference in numbers of peritoneal cysticerci recovered 30 days after infection. The genetic basis of this inter-strain difference was explored using 34 AcB/BcA recombinant congenic strains derived from A/J and B6 progenitors, that were phenotyped for T. crassiceps replication. In agreement with their genetic background, most AcB strains (A/J-derived) were found to be permissive to infection while most BcA strains (B6-derived) were restrictive with the exception of a few discordant strains, together suggesting a possible simple genetic control. Initial haplotype association mapping using >1200 informative SNPs pointed to linkages on chromosomes 2 (proximal) and 6 as controlling parasite replication in the AcB/BcA panel. Additional linkage analysis by genome scan in informative [AcB55xDBA/2]F1 and F2 mice (derived from the discordant AcB55 strain), confirmed the effect of chromosome 2 on parasite replication, and further delineated a major locus (LOD = 4.76, p<0.01; peak marker D2Mit295, 29.7 Mb) that we designate Tccr1 (T. crassiceps cysticercosis restrictive locus 1). Resistance alleles at Tccr1 are derived from AcB55 and are inherited in a dominant fashion. Scrutiny of the minimal genetic interval reveals overlap of Tccr1 with other host resistance loci mapped to this region, most notably the defective Hc/C5 allele which segregates both in the AcB/BcA set and in the AcB55xDBA/2 cross. These results strongly suggest that the complement component 5 (C5) plays a critical role in early protective inflammatory response to infection with T. crassiceps

Identification and characterization of the genetic component of differential susceptibility to mouse malaria

Using strain distribution pattern in a series of recombinant inbred strains derived from malaria susceptible A/J and resistant C57BL/6J (B6) inbred strains of mice, it was established that the genetic control of infection with Plasmodium chabaudi AS is multigenic. Quantitative trait linkage analysis in backcross and F2 crosses derived from A/J and B6 mice identified a major locus on mouse chromosome 8 (Pchr/Char2) controlling the extend of blood-stage parasite replication. The Chr.8 interval contains several candidate genes, one of them being the macrophage scavenger (Scvr) locus encoding for the scavenger receptor type A (SR-AI/AII) expressed at the surface of monocytes and macrophages. The possible role of the SR-A in host defense, and particularly as a candidate for being Char2, was investigated. Sequencing of the coding region and immunoprecipitation of the receptors from A/J and B6 mice, as well as functional studies in transfected CHO cells showed that the B6 strain has a particular haplotype at the Scvr locus. Despite the fact that a link between differential function of SR-A and resistance/susceptibility to P. chabaudi AS was not established, results have shown that the conformation of B6 SR-A at the cell surface differ from one of the known haplotype. Novel loci regulating response to P. chabaudi AS infection were investigated using an alternative strategy based on a newly derived set of AcB/BcA recombinant congenic strains (RCS) bred from A/J and B6 strains. One of the AcB strains, AcB55, was shown to be highly resistant to infection despite having 83% susceptible A/J genomic composition, which includes susceptibility alleles at Char2. Linkage analysis in an informative (AcB55 X A) F2 population located a new resistance locus on chromosome 3 (Char4). Early onset of parasite clearance in AcB55 is associated with lower peak parasitemia and absence of mortality. Investigation of possible mechanisms mediating P. chabaudi AS resistan

Comparative oral bioavailability of non-fixed and fixed combinations of artesunate and amodiaquine in healthy Indian male volunteers

OBJECTIVE: The aim of the present study was to compare the pharmacokinetic properties, bioavailability and tolerability of artesunate (AS) and amodiaquine (AQ) administered as a fixed-dose combination (Amonate FDC tablets; Dafra Pharma, Turnhout, Belgium) or as a non-fixed dose combination of separate AS tablets (Arsuamoon; Guilin Pharmaceutical Co, Shanghai, China) and AQ tablets (Flavoquine; Sanofi-Aventis, Paris, France). METHODS: This was a randomized, open label, two-period, two-treatment, two-sequence, cross-over study in which 60 healthy male Indian volunteers were given a single total oral dose of 100 mg AS and 400 mg AQ hydrochloride either as two tablets of Amonate FDC (AS 50 mg and AQ hydrochloride 200 mg) or as two AS tablets of the co-blister Arsuamoon (50 mg AS) together with two Flavoquine tablets (200 mg AQ hydrochloride). Plasma AS and blood AQ concentrations, as well as those of their respective active metabolites dihydroartemisinin (DHA) and desethylamodiaquine (DEAQ), were measured by high-performance liquid chromatography-tandem spectrometry. The pharmacokinetic parameters of AS, DHA, AQ and DEAQ were determined by non-compartmental analysis. Bioequivalence assessment was performed by analysis of variance (ANOVA), and calculation of the 90% confidence intervals of the geometric mean ratio test (fixed)/reference (non-fixed) for AUC(0-t) and C(max) for AS, AQ, DHA and DEAQ. RESULTS: Interim analysis showed that both treatments were not bioequivalent; therefore, statistical analysis was carried out on the results of all subjects for whom blood/plasma concentrations were available for all four analytes (n=26). The C(max) (maximum plasma/blood concentration) of AS was 67.0 ± 37.1 and 154.8 ± 116.2 ng/mL for the fixed-dose and non-fixed dose administration, respectively. The AUC(0-t) (area under the plasma concentration-time curve from time zero to the last measurable concentration) of AS was 60.1 ± 27.5 and 81.8 ± 44.3 ng h/mL for the fixed-dose and non-fixed dose administration, respectively. The 90% confidence intervals for C(max) and AUC(0-t) of AS were outside the 80-125% acceptance range: 37.02-61.62% and 70.10-83.47%, respectively. The C(max) of AQ was 33.8 ± 13.6 and 31.4 ± 14.1 ng/mL for the fixed-dose and non-fixed dose administration, respectively. The AUC(0-t) of AQ was 332.3 ± 116.6 and 329.8 ± 99.5 ng h/mL for the fixed and non-fixed dose administration, respectively. For AQ, the 90% CIs for C(max) and AUC(0-t) were within the 80-125% acceptance range: 99.17-121.71 and 89.53-107.35%, respectively. Bioequivalence assessment based on the active metabolite data supported the bioequivalence conclusions based on the parent compound data. Both the fixed-dose and non-fixed dose administration of 100 mg AS and 400 mg AQ were well tolerated. CONCLUSION: Bioequivalence of the fixed-dose AS/AQ formulation with the non-fixed dose combination of the same drugs was not demonstrated for AS, but it was shown for AQ for both C(max) and AUC(0-t). The results obtained on the active metabolites support this conclusion. Overall, the fixed-dose 50 mg AS/200 mg AQ tablets were not technically bioequivalent with 50 mg AS tablets and 200 mg AQ tablets administered separately. The difference cannot be explained by the pharmaceutical properties of the tablets and seems to be biologically related

Challenges faced by multidisplinary new investigators on addressing grand challenges in global health

Background. The grand challenges approach aims to spark innovative and transformative strategies to overcome barriers to significant global health issues. Grand Challenges Canada endorses an ‘Integrated Innovation™’ approach that focuses on the intersection of scientific/technological, social and business innovation. In this article we explore themes emerging from a dialogue between the authors, who are multidisciplinary recipients of the ‘Rising Stars in Global Health’ award from Grand Challenges Canada, regarding benefits of engaging in integrated innovation research, and recommendations for how this approach may develop in the future. Discussion Our dialogue followed a semi-structured interview format that addressed three topics: 1) reflections on applying an Integrated Innovation™ approach for global health; 2) thoughts on participation in the Grand Challenges 2012 meeting; and 3) authors’ visions of Grand Challenges Canada and the Grand Challenge movement towards 2020. The dialogue was transcribed verbatim and we used thematic analysis techniques to identify, analyze and report themes in the data. Benefits of working using the Grand Challenges approach centered on two themes: a) the potential for scientific breakthrough and b) building interdisciplinary collaborations and a community of scholars. Challenges and opportunities for Grand Challenges in moving forward included: a) capacity building, particularly regarding Integrated Innovation™ and scale-up planning; b) interdisciplinary and international mentorship for new investigators; and c) potential for future commercialization. Conclusions Our discussion highlighted that Integrated Innovation™ offers the opportunity to develop new theories, methods and approaches to global health while simultaneously fostering a collaborative spirit grounded in international, interdisciplinary collaborations. However, the arguable over-emphasis on corporatization poses a major challenge for new investigators. We propose a more balanced way forward that can harness technology to foster mentorship across time and space to support the development of such skills and ideas among new investigators.Microbiology and Immunology, Department ofScience, Faculty ofOther UBCNon UBCReviewedFacult

Challenges faced by multidisplinary new investigators on addressing grand challenges in global health

Abstract Background The grand challenges approach aims to spark innovative and transformative strategies to overcome barriers to significant global health issues. Grand Challenges Canada endorses an ‘Integrated Innovation™’ approach that focuses on the intersection of scientific/technological, social and business innovation. In this article we explore themes emerging from a dialogue between the authors, who are multidisciplinary recipients of the ‘Rising Stars in Global Health’ award from Grand Challenges Canada, regarding benefits of engaging in integrated innovation research, and recommendations for how this approach may develop in the future. Discussion Our dialogue followed a semi-structured interview format that addressed three topics: 1) reflections on applying an Integrated Innovation™ approach for global health; 2) thoughts on participation in the Grand Challenges 2012 meeting; and 3) authors’ visions of Grand Challenges Canada and the Grand Challenge movement towards 2020. The dialogue was transcribed verbatim and we used thematic analysis techniques to identify, analyze and report themes in the data. Benefits of working using the Grand Challenges approach centered on two themes: a) the potential for scientific breakthrough and b) building interdisciplinary collaborations and a community of scholars. Challenges and opportunities for Grand Challenges in moving forward included: a) capacity building, particularly regarding Integrated Innovation™ and scale-up planning; b) interdisciplinary and international mentorship for new investigators; and c) potential for future commercialization. Conclusions Our discussion highlighted that Integrated Innovation™ offers the opportunity to develop new theories, methods and approaches to global health while simultaneously fostering a collaborative spirit grounded in international, interdisciplinary collaborations. However, the arguable over-emphasis on corporatization poses a major challenge for new investigators. We propose a more balanced way forward that can harness technology to foster mentorship across time and space to support the development of such skills and ideas among new investigators