EXOC8 of Epinephelus coioides involved in SGIV infection via innate immunity and apoptosis

Abstract

The exocyst complex (EXOC) plays a major role in the extracellular secretion of organisms. In this study, EXOC8, a member of the EXOC family, was characterized from Epinephelus coioides,an important economical important fish in southern China and Southeast Asia, and its role response to viral infection was explored. The full length of E. coioides EXOC8 is 3091 bp including a 2061 bp open reading frame (ORF) encoding 686 amino acids, with a molecular mass of 79037.42 Da. The mRNA of E. coioides EXOC8 can be detected in all of the tissues examined with different levels. E. coioides EXOC8 is distributed in the cytoplasm. The expression of E. coioides EXOC8 was up-regulated during Singapore grouper iridovirus (SGIV) infection, an important pathogen of E. coioides. Overexpressing E. coioides EXOC8 significantly promoted the formation of cytopathic effects (CPE) caused by SGIV infection and the expressions of SGIV key genes MCP, VP19, LITAF and ICP18; but significantly inhibited the activities of NF-κB/AP-1 promoter, apoptosis induced by SGIV, and the expressions of inflammatory factors (IL-6,IL-8, IL-1β and TNF-α) in E. coioides. The results demonstrated that E. coioides EXOC8 may be involved in SGIV infection, providing a theoretical basis for clearing the mechanisms of viral infection in fish.