Nowadays, fish production through aquaculture and wild capture is escalating due to the higher fish protein demand for human consumption. Thus, the needs for fish products to be improved in scale and quality are becoming increasingly important to meet the nutrition requirements. The negative impacts caused by pathogens infection both in hatchery and grow-out ponds, have resulted in low aquaculture productivity and economic losses for the farmers. Therefore, a systematic study exploring relevant omics datasets through a systems biology approach will enable scientist to describe the complexity and characteristics of interactions in the host-pathogen network, leading to identifying new targets or biomarkers for diseases infection caused by bacteria, viruses, and parasites. The use of different approaches and emerging technologies as a powerful tool in obtaining a new knowledge for sustainable aquaculture production has been increasingly applied by many researchers over the years. In this paper, several omics approaches used to assess the fish immune response were reviewed. A brief description is provided for the omics approaches applicable to aquacultures, such as genomics, transcriptomics, proteomics, and metabolomics. Each tool used are contributes to develop better treatment and prevention strategies to overcome aquaculture disease due to the microbial infections. In genomics and transcriptomics analysis, their parallel approach involving gene expression studies play important role in identifying immune-related genes of the host, response to infectious diseases. While for proteomics and metabolomics approaches, these omics will provide information on the biomarker discovery and understanding the immune-related biosynthetic pathway during pathogen infection. Additionally, examples of the integrative analysis of multi-omics tools required for researchers to better understand the biological systems of aquatic animals especially fish, will also be provided.
Aquaculture has been expanding in Malaysia due to the increased demand for fish products. In addition, aquaculture faces challenges in maintaining feed suitability in support of the global growth of fish production. Therefore, improvements in diet formulation are necessary to achieve the optimal requirements and attain a desirable growth efficiency and health performance in fish. Seven weeks of study were conducted to compare the equal amounts of different fatty acids (2%) (oleic acid, stearic acid, palmitic acid, and behenic acid) on the survival, the growth, and the immune response of hybrid grouper (Epinephelus fuscoguttatus × Epinephelus lanceolatus) against V. vulnificus. After six weeks of the feeding trial, fish were challenged with V. vulnificus for 30 min before continuing on the same feeding regime for the next seven days (post-bacterial challenge). Fish supplemented with dietary oleic acid showed significantly (p < 0.05) enhanced immune responses, i.e., lysozyme, respiratory burst, and phagocytic activities compared to the control diet group for both pre-and post-bacterial challenges. Following the Vibrio challenge, no significant effects of supplemented fatty acid diets on survival rate were observed, although dietary oleic acid demonstrated the highest 63.3% survival rate compared to only 43.3% of the control diet group. In addition, there were no significant effects (p > 0.05) on specific growth rate (SGR), white blood cell (WBC), and red blood cell (RBC) counts among all experimental diets. The results from this study suggest that among the tested dietary fatty acids, the oleic acid diet showed promising results in the form of elevated immune responses and increased disease resistance of the hybrid grouper fingerlings challenged with V. vulnificus.
Aquaculture is an important industry globally as it remains one of the significant alternatives of animal protein source supplies for humankind. Yet, the progression of this industry is being dampened by the increasing rate of fish mortality, mainly the outbreak of infectious diseases. Consequently, the regress in aquaculture ultimately results in the economy of multiple countries being affected due to the decline of product yields and marketability. By 2025, aquaculture is expected to contribute approximately 57% of fish consumption worldwide. Without a strategic approach to curb infectious diseases, the increasing demands of the aquaculture industry may not be sustainable and hence contributing to the over-fishing of wild fish. Recently, a new holistic approach that utilizes multi-omics platforms including transcriptomics, proteomics, and metabolomics is unraveling the intricate molecular mechanisms of host-pathogen interaction. This approach aims to provide a better understanding of how to improve the resistance of host species. However, no comprehensive review has been published on multi-omics strategies in deciphering fish disease etiology and molecular regulation. Most publications have only covered particular omics and no constructive reviews on various omics findings across fish species, particularly on their immune systems, have been described elsewhere. Our previous publication reviewed the integration of omics application for understanding the mechanism of fish immune response due to microbial infection. Hence, this review provides a thorough compilation of current advancements in omics strategies for fish disease management in the aquaculture industry. The discovery of biomarkers in various fish diseases and their potential advancement to complement the recent progress in combatting fish disease is also discussed in this review.
The aim of this study was to evaluate the impact of oleic acid supplements on the liver metabolome of hybrid grouper fingerlings (Epinephelus fuscoguttatus × Epinephelus lanceolatus) challenged with Vibrio vulnificus. Oleic acid was used as a fish feed supplement because it has been reported to enhance the immune response of fish. After six weeks of feeding trials with the control and experimental diets (oleic acid immunostimulant), 10 fish were randomly selected from each treatment and challenged with V. vulnificus by immersion for 30 min. After seven days of post-bacterial challenge, the liver samples of surviving infected groupers were dissected and used for metabolomics fingerprinting using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-qTOF-MS). The results were then analyzed using MetaboAnalyst 5.0 and SIMCA+P software. From the analyses conducted, out of 639 primary metabolites detected, a total of 66 metabolites were significantly identified from the liver samples of grouper fed control and oleic acid diets. Further analysis also showed that the control and oleic acid diets have significantly different metabolites by the discriminating clustering of samples based on the PLS-DA analysis. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, the known metabolites pathways with high impact values are alanine, aspartate, and glutamate metabolism (0.13) followed by purine metabolism pathways (0.05). Moreover, out of these highly impacted metabolic pathways, L-glutamine (8.71%), L-lysine (4.05%), L-carnitine (11.53%), and inosine (10.49%) were the several metabolites that were highly abundant in the liver sample of surviving infected hybrid groupers fed with dietary oleic acid. The changes of metabolites contributed to improving the immune system of the fish. Thus, our results advance our understanding of the immunological regulation of the hybrid groupers’ immune response toward oleic acid immunostimulants against Vibrio infection.
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