Response signatures of intestinal microbiota and gene transcription of the tiger grouper Epinephelus fuscoguttatus to nervous necrosis virus infection

Abstract

Groupers culture are severely affected by infectious diseases. Nervous necrosis virus (NNV) can destroy the nervous system and causes massive deaths. Intestinal microbiota is an important biological barrier against pathogen invasion. In this study, we investigated the changes in intestinal microbial community and gene transcription of tiger grouper following NNV infection. Compared with the control group, the richness and diversity of intestinal microbial was induced by NNV infection, with the increased level of Firmicutes (especially class Bacilli and Clostridia) and decreased levels of Proteobacteria and Bacteroidetes. Several genus such as Lactobacillus, Acinetobacter, Escherichia-Shigella, Enterobacter, Flavobacterium and Stenotrophomonas were increased, while Alloprevotella, Bacteroides and Demequina were decreased. The carbohydrate metabolism of intestinal microbial was also decreased. The differentially expressed genes in head kidney were mainly associated with hemopoiesis and the development of immune system and hematopoietic or lymphoid organ. Several immune-related genes such as MHC class II antigen, CXC chemokine receptors (CXCR1 and CXCR4), heat shock proteins (HSP60, HSP70, HSP90), cytochrome C, immunoglobulin light chain and hepcidin were up-regulated, while interleukin (IL-8 nd IL-15), CXCR3 and complement (C1QL3 and C7) were down-regulated. These results revealed that NNV infection caused intestinal microbiota variation and affected the immunity of tiger grouper, which will be beneficial to utilize the characteristics of intestinal microbial to facilitate grouper healthy culture.