Understanding regulation of the host-mediated gut symbiont population and the symbiont-mediated host immunity in the Riptortus-Burkholderia symbiosis system

• Published in: Developmental and comparative immunology Vol. 64; pp. 75 - 81
• Main Authors: Kim, Jiyeun Kate, Lee, Jun Beom, Jang, Ho Am, Han, Yeon Soo, Fukatsu, Takema, Lee, Bok Luel
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.11.2016
• Subjects: Animals; Antimicrobial Cationic Peptides - metabolism; Antimicrobial peptide; Bacterial Infections - immunology; Bacterial Infections - microbiology; Burkholderia; Burkholderia - immunology; Burkholderia symbiont; Cell Wall - metabolism; Disease Susceptibility; Gut immunity; Hemiptera - immunology; Immunity, Innate; Innate immunity; Insect symbiosis; Intestines - immunology; Intestines - microbiology; Microbiota; Models, Animal; Riptortus pedestris; Symbiosis; Gut immunity; Innate immunity; Insect symbiosis; Riptortus pedestris; Burkholderia symbiont; Antimicrobial peptide
• ISSN: 0145-305X; 1879-0089
• DOI: 10.1016/j.dci.2016.01.005

Valuable insect models have tremendously contributed to our understanding of innate immunity and symbiosis. Bean bug, Riptortus pedestris, is a useful insect symbiosis model due to harboring cultivable monospecific gut symbiont, genus Burkholderia. Bean bug is a hemimetabolous insect whose immunity is not well-understood. However, we recently identified three major antimicrobial peptides of Riptortus and examined the relationship between gut symbiosis and host immunity. We found that the presence of Burkholderia gut symbiont positively affects Riptortus immunity. From studying host regulation mechanisms of symbiont population, we revealed that the symbiotic Burkholderia cells are much more susceptible to Riptortus immune responses than the cultured cells. We further elucidated that the immune-susceptibility of the Burkholderia gut symbionts is due to the drastic change of bacterial cell envelope. Finally, we show that the immune-susceptible Burkholderia symbionts are able to prosper in host owing to the suppression of immune responses of the symbiotic midgut. •Riptortus pedestris is a useful insect model to study symbiosis and gut immunity.•Gut symbionts enhance host innate immunity in the Riptortus-Burkholderia system.•Burkholderia cells becomes susceptible to host immunity by cell envelope changes.