Transcriptome Analysis in the Head Kidney of Rainbow Trout (Oncorhynchus mykiss) Immunized with a Combined Vaccine of Formalin-Inactivated Aeromonas salmonicida and Vibrio anguillarum.

Jongwon Lim,Suhee Hong

doi:10.3390/vaccines9111234

Abstract

This study aimed to identify the molecular mechanisms regulated by a combined vaccine against Aeromonas salmonicida and Vibrio anguillarum (O1 serotype). These bacteria cause furunculosis and vibriosis, respectively, and are associated with a high mortality in rainbow trout in Korea. The vaccine upregulated gene expression of TCRα, T-bet, sIgM, and mIgM, markers of an activated adaptive immune response. On days 1, 3, and 5, transcriptome analysis revealed 862 (430 up- and 432 downregulated), 492 (204 up- and 288 downregulated), and 741 (270 up- and 471 downregulated) differentially expressed genes (DEGs), respectively. Gene ontology (GO) enrichment analysis identified 377 (108 MF, 132 CC, 137 BP), 302 (60 MF, 180 CC, 62 BP), and 314 (115 MF, 129 CC, 70 BP) GOs at days 1, 3, and 5, respectively. Kyoto Encyclopedia of Genetic and Genomic enrichment analysis identified eight immune system-related pathways like cytokine-cytokine receptor interaction, NF-kappaB signaling pathway, TNF signaling pathway, NOD-like receptor signaling pathway, cytosolic DNA sensing pathway, cell adhesion molecule, complement and coagulation cascade, and antigen processing and presentation. In the analysis of the protein–protein interaction of immune-related DEGs, a total of 59, 21, and 21 interactional relationships were identified at days 1, 3, and 5, respectively, with TNF having the highest centrality at all three time points.

Highlights

Rainbow trout (Oncorhynchus mykiss) is a cold-water fish popular for aquaculture worldwide due to its rapid growth rate and fertility [1]
In shaking incubators at 180 rpm, a single colony of A. salmonicida RTDH or V. anguillarum RTBHR isolates was incubated in tryptic soy broth (TSB) at 20 ◦ C for 48 h or TSB supplemented with 2% sodium chloride at 25 ◦ C for 24 h, respectively
Numerous reports indicate that vaccines against A. salmonicida and V. anguillarum play an important role during bacterial infection in rainbow trout

Summary

Introduction

Rainbow trout (Oncorhynchus mykiss) is a cold-water fish popular for aquaculture worldwide due to its rapid growth rate and fertility [1]. In Korea, it is a major inland aquaculture species after eel (Anguilliformes), golden apple snail (Pomacea canaliculata), catfish (Silurus asotus), and crucian carp (Carassius carassius) [2]. Aeromonas salmonicida and Vibrio anguillarum are gram-negative bacteria associated with major diseases in Salmonids, leading to high mortality and morbidity [3,4]. A. salmonicida is the causative agent of furunculosis with symptoms of muscle ulceration, hemorrhagic sepsis, and death [4]. V. anguillarum causes vibriosis in Salmonids and other fish species and is one of the most frequent aquatic diseases worldwide [5]. In Korea, only serotype 1 of V. anguillarum has been isolated so far [6]

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