title: Alternative oxidase mediates pathogen resistance in Paracoccidioides brasiliensis infection.
abstract: BACKGROUND
  Paracoccidioides brasiliensis is a human thermal dimorphic pathogenic fungus. Survival of P. brasiliensis inside the host depends on the adaptation of this fungal pathogen to different conditions, namely oxidative stress imposed by immune cells.
  
  
  OBJECTIVE
  In this study, we evaluated the role of alternative oxidase (AOX), an enzyme involved in the intracellular redox balancing, during host-P. brasiliensis interaction. We generated a mitotically stable P. brasiliensis AOX (PbAOX) antisense RNA (aRNA) strain with a 70% reduction in gene expression. We evaluated the relevance of PbAOX during interaction of conidia and yeast cells with IFN-γ activated alveolar macrophages and in a mouse model of infection. Additionally, we determined the fungal cell's viability and PbAOX in the presence of H₂O₂.
  
  
  RESULTS
  Interaction with IFN-γ activated alveolar macrophages induced higher levels of PbAOX gene expression in PbWt conidia than PbWt yeast cells. PbAOX-aRNA conidia and yeast cells had decreased viability after interaction with macrophages. Moreover, in a mouse model of infection, we showed that absence of wild-type levels of PbAOX in P. brasiliensis results in a reduced fungal burden in lungs at weeks 8 and 24 post-challenge and an increased survival rate. In the presence of H₂O₂, we observed that PbWt yeast cells increased PbAOX expression and presented a higher viability in comparison with PbAOX-aRNA yeast cells.
  
  
  CONCLUSIONS
  These data further support the hypothesis that PbAOX is important in the fungal defense against oxidative stress imposed by immune cells and is relevant in the virulence of P. brasiliensis.
authors: Instituto de Biología, Universidad de Antioquia, Medellín, Colombia. orvillehr@hotmail.com
authors: Orville Hernández
authors: OH
authors: Ruiz
authors: Angel
authors: A
authors: Gonzalez
authors: Agostinho J
authors: AJ
authors: Almeida
authors: Diana
authors: D
authors: Tamayo
authors: Ana Maria
authors: AM
authors: Garcia
authors: Angela
authors: A
authors: Restrepo
authors: Juan G
authors: JG
authors: McEwen
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D055785:Gene Knockdown Techniques; D006861:Hydrogen Peroxide / Q000633:toxicity; D008168:Lung / Q000382:microbiology; D008264:Macrophages / Q000276:immunology / Q000382:microbiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D050296:Microbial Viability; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016877:Oxidants / Q000633:toxicity; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010228:Paracoccidioides / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology / Q000472:pathogenicity*; D010229:Paracoccidioidomycosis / Q000382:microbiology / Q000473:pathology; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016372:RNA, Antisense / Q000235:genetics / Q000378:metabolism; D016019:Survival Analysis; D014774:Virulence; D037521:Virulence Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000099188:Alternative Oxidase
chemical_list: D006861:Hydrogen Peroxide; D024101:Mitochondrial Proteins; D016877:Oxidants; D010088:Oxidoreductases; D010940:Plant Proteins; D016372:RNA, Antisense; D037521:Virulence Factors; D000099188:Alternative Oxidase