Susceptibility to Mycobacterium ulcerans Disease (Buruli ulcer) Is Associated with IFNG and iNOS Gene Polymorphisms
FRONTIERS IN MICROBIOLOGY
Authors: Bibert, Stephanie; Bratschi, Martin W.; Aboagye, Samuel Y.; Collinet, Emilie; Scherr, Nicole; Yeboah-Manu, Dorothy; Beuret, Christian; Pluschke, Gerd; Bochud, Pierre-Yves
Abstract
Buruli ulcer (BU) is a chronic necrotizing disease of the skin and subcutaneous fat tissue. The causative agent, Mycobacterium ulcerans, produces mycolactone, a macrolide toxin, which causes apoptosis of mammalian cells. Only a small proportion of individuals exposed to M. ulcerans develop clinical disease, as surrounding macrophages may control the infection by bacterial killing at an early stage, while mycolactone concentration is still low. Otherwise, bacterial multiplication leads to in higher concentrations of mycolactone, with formation of necrotizing lesions that are no more accessible to immune cells. By typing a cohort of 96 Ghanaian BU patients and 384 endemic controls without BU, we show an association between BU and single nucleotide polymorphisms (SNPs) in iNOS (rs9282799) and IFNG (rs2069705). Both polymorphisms influence promoter activity in vitro. A previously reported SNP in SLC11A1 (NRAMP, rs17235409) tended to be associated with BU. Altogether, these data reflect the importance of IFNG signaling in early defense against M. ulcerans infection.
Navigating to the most promising directions amid complex fields of vaccine development: a chlamydial case study
EXPERT REVIEW OF VACCINES
Authors: Lizarraga, David; Carver, Scott; Timms, Peter
Abstract
Background: Vaccine-development research is proliferating making it difficult to determine the most promising vaccine candidates. Exemplary of this problem is vaccine development against Chlamydia, a pathogen of global public health and financial importance. Methods: We systematically extracted data from studies that included chlamydial load or host immune parameter measurements, estimating 4,453 standardized effect sizes between control and chlamydial immunization experimental groups. Results: Chlamydial immunization studies most often used (78%) laboratory mouse models. Depending on chlamydial species, single and multiple recombinant protein, viral and bacterial vectors, dendritic transfer, and dead whole pathogen were most effective at reducing chlamydial load. Immunization-driven decrease in chlamydial load was associated with increases in IFNg, IgA, IgG1, and IgG2a. Using data from individual studies, the magnitude of IgA and IgG2a increase was correlated with chlamydial load reduction. IFNg also showed this pattern for C. trachomatis, but not for C. muridarum. We also reveal the chlamydial vaccine development field to be highly bias toward studies showing these effects, limiting lessons learned from negative results. Conclusions: Most murine immunizations against Chlamydia reduced chlamydial load and increased host immune parameters. These methods are novel for vaccine development and are critical in identifying trends where large quantities of literature exist.