The effects of inactivation methods of Yersinia ruckeri on the efficacy of single dip vaccination in Atlantic salmon (Salmo salar)

Comparative Transcriptomics in Atlantic Salmon Head Kidney and SHK-1 Cell Line Exposed to the Sea Louse Cr-Cathepsin

The development of vaccines against sea lice in salmon farming is complex, expensive, and takes several years for commercial availability. Recently, transcriptome studies in sea louse have provided valuable information for identifying relevant molecules with potential use for fish vaccines. However, the bottleneck is the in vivo testing of recombinant protein candidates, the dosage, and the polyvalent formulation strategies. This study explored a cell-based approach to prospect antigens as candidate vaccines against sea lice by comparison with immunized fish. Herein, SHK-1 cells and Atlantic salmon head kidney tissue were exposed to the antigen cathepsin identified from the sea louse Caligus rogercresseyi. The cathepsin protein was cloned and recombinantly expressed in Escherichia coli, and then SHK-1 cell lines were stimulated with 100 ng/mL cathepsin recombinant for 24 h. In addition, Atlantic salmons were vaccinated with 30 ug/mL recombinant protein, and head kidney samples were then collected 30 days post-immunization. SHK-1 cells and salmon head kidney exposed to cathepsin were analyzed by Illumina RNA sequencing. The statistical comparisons showed differences in the transcriptomic profiles between SHK-1 cells and the salmon head kidney. However, 24.15% of the differentially expressed genes were shared. Moreover, putative gene regulation through lncRNAs revealed tissue-specific transcription patterns. The top 50 up and downregulated lncRNAs were highly correlated with genes involved in immune response, iron homeostasis, pro-inflammatory cytokines, and apoptosis. Also, highly enriched pathways related to the immune system and signal transduction were shared between both tissues. These findings highlight a novel approach to evaluating candidate antigens for sea lice vaccine development, improving the antigens screening in the SHK-1 cell line model.

A review on the recent advances and application of vaccines against fish pathogens in aquaculture

Globally, aquaculture has faced serious economic problems due to bacterial, viral, and various other infectious diseases of different origins. Even though such diseases are being detected and simultaneously treated with several therapeutic and prophylactic methods, the broad-spectrum activity of vaccines plays a vital role as a preventive measure in aquaculture. However, treatments like use of antibiotics and probiotics seem to be less effective when new mutant strains develop and disease causing pathogens become resistant to commonly used antibiotics. Therefore, vaccines developed by using recent advanced molecular techniques can be considered as an effective way of treating disease causing pathogens in aquatic organisms. The present review emphasizes on the current advances in technology and future outlook with reference to different types of vaccines used in the aquaculture industries. Beginning with traditional killed/inactivated and live attenuated vaccines, this work culminates in the review of modern new generation ones including recombinant, synthetic peptides, mucosal and DNA, subunit, nanoparticle-based and plant-based edible vaccines, reverse vaccinology, and monovalent and polyvalent vaccines.

Testing Novel Inactivation Methods and Adjuvants for Vaccines Against Streptococcus agalactiae in Nile Tilapia Oreochromis niloticus

Inactivation by hydrogen peroxide and pH manipulation are two novel methods used recently in experimental vaccines against Streptococcus agalactiae in Nile tilapia. Here we describe in detail inactivation using novel methods as well as the classical method of inactivation. These vaccines showed similar moderate efficacy when compared to the conventional formaldehyde vaccine. In addition, we describe the inclusion of adjuvants in a hydrogen peroxide vaccine.

State-of-the-Art Vaccine Research for Aquaculture Use: The Case of Three Economically Relevant Fish Species

In the last three decades, the aquaculture sector has experienced a 527% growth, producing 82 million tons for a first sale value estimated at 250 billion USD. Infectious diseases caused by bacteria, viruses, or parasites are the major causes of mortality and economic losses in commercial aquaculture. Some pathologies, especially those of bacterial origin, can be treated with commercially available drugs, while others are poorly managed. In fact, despite having been recognized as a useful preventive measure, no effective vaccination against many economically relevant diseases exist yet, such as for viral and parasitic infections. The objective of the present review is to provide the reader with an updated perspective on the most significant and innovative vaccine research on three key aquaculture commodities. European sea bass (Dicentrarchus labrax), Nile tilapia (Oreochromis niloticus), and Atlantic salmon (Salmo salar) were chosen because of their economic relevance, geographical distinctiveness, and representativeness of different culture systems. Scientific papers about vaccines against bacterial, viral, and parasitic diseases will be objectively presented; their results critically discussed and compared; and suggestions for future directions given.