Immunity-Related Genes and Gene Families in Anopheles gambiae
Christophides GK., Zdobnov E., Barillas-Mury C., Birney E., Blandin S., Blass C., Brey PT., Collins FH., Danielli A., Dimopoulos G., Hetru C., Hoa NT., Hoffmann JA., Kanzok SM., Letunic I., Levashina EA., Loukeris TG., Lycett G., Meister S., Michel K., Moita LF., Müller H-M., Osta MA., Paskewitz SM., Reichhart J-M., Rzhetsky A., Troxler L., Vernick KD., Vlachou D., Volz J., von Mering C., Xu J., Zheng L., Bork P., Kafatos FC.
We have identified 242 Anopheles gambiae genes from 18 gene families implicated in innate immunity and have detected marked diversification relative to Drosophila melanogaster . Immune-related gene families involved in recognition, signal modulation, and effector systems show a marked deficit of orthologs and excessive gene expansions, possibly reflecting selection pressures from different pathogens encountered in these insects' very different life-styles. In contrast, the multifunctional Toll signal transduction pathway is substantially conserved, presumably because of counterselection for developmental stability. Representative expression profiles confirm that sequence diversification is accompanied by specific responses to different immune challenges. Alternative RNA splicing may also contribute to expansion of the immune repertoire.