Proteomic Analysis of Formosan Subterranean Termites During Exposure to Entomopathogenic Fungi

Background: Formosan Subterranean termites, Coptotermes formosanus Shiraki are sustaining in microbe-rich environment of the nest. The successful foraging and survival of termites within the nest revealed the adaptation of exceptional host-defence mechanism. There is an inherent need to unravel termites immune defence mechanism for knowledgeable host-pathogen understanding. Objective: Comparative protein expression pattern among uninfected and immunized Coptotermes formosanus Shiraki workers was explored for the first time to gain better understanding of host immune response to entomopathogenic fungi including Metarhizium anisopliae and Beauveria bassiana. Method: In this study, we analyzed the immune-related proteomic profile of C. formosanus Shiraki workers infected with entomopathogenic fungi including M. anisopliae and B. bassiana. After immunization confirmation by antifungal activity bioassays, homogenates were fractionated by cation exchange chromatography. Antifungal fractions were further analyzed by two-dimensional gel electrophoresis. Results: We obtained approximately 846 protein spots from uninfected, 709 from workers infected with M. anisopliae and 776 from B. bassiana. A total of 170 peptide fragments from 44 spots were identified to be immune-related by MALDI/TOF/MS. Among them, 20 proteins matched with sequences of C. formosanus. Identified immune related proteins trigger Toll and JAK-STAT pathways and were categorized into six types: five of them were pattern recognition receptors, five proteins were signal modulators, five of them involved in signal transduction, two effectors, four antioxidants and eleven other immune related proteins. Conclusion: Identified immune-related proteins indicate the existence of sophisticated immune mechanism against each pathogen and provide more information for further comprehension on the molecular mechanism of disease resistance among termites.