A multi-institutional research team has revealed the genome sequence of the human body louse, Pediculus humanus humanus, and that of an essential bacterium, or endosymbiont, in the louse gut (Kirkness EF et al. Proc Natl Acad Sci U S A. doi:10.1073/pnas.1003379107 [published online June 21, 2010]).
Analysis of the body louse genome revealed that it is the smallest known insect genome and that it contains few genes associated with environmental sensing and response. Features of the endosymbiont's genome include a unique arrangement of genes required for the synthesis of pantothenate, an essential vitamin deficient in the louse diet, and a lack of antibiotic resistance genes.
Hampton T. Body Louse Genome. JAMA. 2010;304(7):733. doi:10.1001/jama.2010.1081