title: Differential gene expression in laboratory strains of human head and body lice when challenged with Bartonella quintana, a pathogenic bacterium.
abstract: Human head and body lice are obligatory hematophagous ectoparasites that belong to a single species, Pediculus humanus. Only body lice, however, are vectors of the infectious Gram-negative bacterium Bartonella quintana. Because of their near identical genomes, yet differential vector competence, head and body lice provide a unique model system to study the gain or loss of vector competence. Using our in vitro louse-rearing system, we infected head and body lice with blood containing B. quintana in order to detect both differences in the proliferation of B. quintana and transcriptional differences of immune-related genes in the lice. B. quintana proliferated rapidly in body lice at 6 days post-infection, but plateaued in head lice at 4 days post-infection. RNAseq and quantitative real-time PCR validation analyses determined gene expression differences. Eight immunoresponse genes were observed to be significantly different with many associated with the Toll pathway: Fibrinogen-like protein, Spaetzle, Defensin 1, Serpin, Scavenger receptor A and Apolipoporhrin 2. Our findings support the hypothesis that body lice, unlike head lice, fight infection from B. quintana only at the later stages of its proliferation.
authors.affiliation: Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Previte
authors.forename: B P
authors.initials: BP
authors.lastname: Olds
authors.forename: K
authors.initials: K
authors.lastname: Yoon
authors.forename: W
authors.initials: W
authors.lastname: Sun
authors.forename: W
authors.initials: W
authors.lastname: Muir
authors.forename: K N
authors.initials: KN
authors.lastname: Paige
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Clark
authors.forename: J E
authors.initials: JE
authors.lastname: Koehler
authors.forename: B R
authors.initials: BR
authors.lastname: Pittendrigh
mesh_terms: D000818:Animals; D018413:Bartonella quintana / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D007303:Insect Vectors / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D010374:Pediculus / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D060888:Real-Time Polymerase Chain Reaction; D013045:Species Specificity; D059467:Transcriptome; D014205:Trench Fever / Q000382:microbiology / Q000635:transmission
keywords: Pediculus humanus capitis; Pediculus humanus humanus; disease vector; ectoparasite; insect; trench fever