Gene expression profiles alteration after infection of virus, bacteria, and parasite in the Olive flounder (Paralichthys olivaceus)

Gyu-Hwi Nam,Kung Ahn,Yung Hyun Choi,Do-Hyung Kim,Ahran Kim,Chan-Il Park,Woo-Jin Kim,Hee-Eun Lee,Ara Jo,Anshuman Mishra,Hee-Jae Cha,Heui-Soo Kim,Dahye Yoon,Suhkmann Kim,Jeong-An Gim

doi:10.1038/s41598-018-36342-y

Abstract

Olive flounder (Paralichthys olivaceus) is one of economically valuable fish species in the East Asia. In comparison with its economic importance, available genomic information of the olive flounder is very limited. The mass mortality caused by variety of pathogens (virus, bacteria and parasites) is main problem in aquaculture industry, including in olive flounder culture. In this study, we carried out transcriptome analysis using the olive flounder gill tissues after infection of three types of pathogens (Virus; Viral hemorrhagic septicemia virus, Bacteria; Streptococcus parauberis, and Parasite; Miamiensis avidus), respectively. As a result, we identified total 12,415 differentially expressed genes (DEG) from viral infection, 1,754 from bacterial infection, and 795 from parasite infection, respectively. To investigate the effects of pathogenic infection on immune response, we analyzed Gene ontology (GO) enrichment analysis with DEGs and sorted immune-related GO terms per three pathogen groups. Especially, we verified various GO terms, and genes in these terms showed down-regulated expression pattern. In addition, we identified 67 common genes (10 up-regulated and 57 down-regulated) present in three pathogen infection groups. Our goals are to provide plenty of genomic knowledge about olive flounder transcripts for further research and report genes, which were changed in their expression after specific pathogen infection.

Highlights

Olive flounder is one of main marine species having high economic value in the countries of East Asia
Viruses, viral hemorrhagic septicemia virus (VHSV) is affiliated to Novirhabdovirus genus, which is a member of the Rhabdoviridae family[4]
Judging from infection experiments using various scuticociliates plus identification outcome of 8 isolates acquired from olive flounders with symptom of ulcers and haemorrhages, Miamiensis avidus was suggested as the major aetiologic agent of scuticociliatosis because of high pathogenicity and mortality rate compared with other scuticociliates[14,17]

Summary

Introduction

Mass mortality of olive flounder was normally caused by diseases via various sources of infection such as virus, bacteria, or parasite from external environment. Infection of VHSV results in contagious viral hemorrhagic septicemia (VHS) in diverse fish species regardless of their inhabitation; seawater or freshwater[5]. Judging from infection experiments using various scuticociliates plus identification outcome of 8 isolates acquired from olive flounders with symptom of ulcers and haemorrhages, Miamiensis avidus was suggested as the major aetiologic agent of scuticociliatosis because of high pathogenicity and mortality rate compared with other scuticociliates[14,17]. Streptococcosis is known to be caused by a variety of streptococcic species; Streptococcus parauberis, Streptococcus iniae, Streptococcus difficilis, Lactococcus garvieae, Lactococcus piscium, Vagococcus salmoninarum, and Carnobacterium piscicola, and has become major nuisance in olive flounder farms[18,19,20,21]. Streptococcus iniae, Lactococcus garvieae, and Streptococcus parauberis have been introduced to be related with Streptococcosis in olive flounder[19,20,21,22,23]

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Conclusion