A viral histone H4 suppresses insect insulin signal and delays host development. (October 2016)

• Record Type: Journal Article
• Authors: Kumar, Sunil; Gu, Xiaojun; Kim, Yonggyun
• Is Part Of: Developmental and comparative immunology. Volume 63(2016)
• Page Start: 66
• Page End: 77
• Publication Date: 2016-10
• Subjects: Insulin -- Parasitism -- Polydnavirus -- Histone H4 -- Trehalose; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2016.05.012
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Parasitization by an endoparasitoid wasp, Cotesia plutellae, alters host development of Plutella xylostella by extending larval period and preventing metamorphosis. Insulin signal plays a crucial role in mediating insect development and controlling blood sugar level in insects. In this study, three insulin-like peptide genes ( PxILP1-3 ) were predicted from the genome of P. xylostella . However, only PxILP1 was confirmed to be expressed in P. xylostella . Starvation suppressed the expression level of PxILP1 and up-regulated plasma trehalose level. RNA interference against PxILP1 mimicked starvation effect and extended the larval period of P. xylostella . Parasitized larvae exhibited significantly lower levels of PxILP1 expression compared to nonparasitized larvae. Injection of wasp-symbiotic polydnavirus C. plutellae bracovirus (CpBV) also suppressed PxILP1 expression and extended the larval period. Injection of a viral segment (CpBV-S30) containing a viral histone H4 (CpBV-H4) also suppressed PxILP1 expression. Co-injection of CpBV-S30 and double-stranded RNA (dsCpBV-H4) specific to CpBV-H4 rescued the suppression of PxILP1 expression. Injection of CpBV-S30 significantly extended larval development. Co-injection of CpBV-S30 with dsCpBV-H4 rescued the delay of larval development. Injection of a bovine insulin to parasitized larvae prevented parasitoid development. These results indicate that parasitism of C. plutellae can down-regulate host insulin signaling with the help of parasitic factor CpBV-H4 . Graphical abstract: Highlights: An insulin-like peptide (PxILP1) facilitates host development. A parasitoid wasp inhibits PxILP1 expression using its symbiotic virus via CpBV-H4. Addition of bovine insulin inhibits the parasitoid development.