title: Humoral responses in Rhodnius prolixus: bacterial feeding induces differential patterns of antibacterial activity and enhances mRNA levels of antimicrobial peptides in the midgut.
abstract: BACKGROUND
  The triatomine, Rhodnius prolixus, is a major vector of Trypanosoma cruzi, the causative agent of Chagas disease in Latin America. It has a strictly blood-sucking habit in all life stages, ingesting large amounts of blood from vertebrate hosts from which it can acquire pathogenic microorganisms. In this context, the production of antimicrobial peptides (AMPs) in the midgut of the insect is vital to control possible infection, and to maintain the microbiota already present in the digestive tract.
  
  
  METHODS
  In the present work, we studied the antimicrobial activity of the Rhodnius prolixus midgut in vitro against the Gram-negative and Gram-positive bacteria Escherichia coli and Staphylococcus aureus, respectively. We also analysed the abundance of mRNAs encoding for defensins, prolixicin and lysozymes in the midgut of insects orally infected by these bacteria at 1 and 7 days after feeding.
  
  
  RESULTS
  Our results showed that the anterior midgut contents contain a higher inducible antibacterial activity than those of the posterior midgut. We observed that the main AMP encoding mRNAs in the anterior midgut, 7 days after a blood meal, were for lysozyme A, B, defensin C and prolixicin while in the posterior midgut lysozyme B and prolixicin transcripts predominated.
  
  
  CONCLUSIONS
  Our findings suggest that R. prolixus modulates AMP gene expression upon ingestion of bacteria with patterns that are distinct and dependent upon the species of bacteria responsible for infection.
authors.forename: Cecilia Stahl
authors.initials: CS
authors.lastname: Vieira
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Waniek
authors.forename: Débora P
authors.initials: DP
authors.lastname: Mattos
authors.forename: Daniele P
authors.initials: DP
authors.lastname: Castro
authors.forename: Cícero B
authors.initials: CB
authors.lastname: Mello
authors.affiliation: Laboratório de Bioquímica e Fisiologia de Insetos, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Rio de Janeiro, Brazil. N.A.Ratcliffe@swansea.ac.uk.
authors.forename: Norman A
authors.initials: NA
authors.lastname: Ratcliffe
authors.forename: Eloi S
authors.initials: ES
authors.lastname: Garcia
authors.forename: Patrícia
authors.initials: P
authors.lastname: Azambuja
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D004926:Escherichia coli / Q000276:immunology / Q000502:physiology*; D041981:Gastrointestinal Tract / Q000378:metabolism* / Q000382:microbiology; D005786:Gene Expression Regulation / Q000276:immunology; D054884:Host-Pathogen Interactions; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012239:Rhodnius / Q000276:immunology*; D013211:Staphylococcus aureus / Q000276:immunology / Q000502:physiology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D012333:RNA, Messenger