Oral Abstracts - From the Fourth Congress of the International Society of Fish & Shellﬁsh Immunology The 4 th Congress of the International Society of Fish & Shellﬁsh Immunology December 12-15, 2022. Bodø, Norway Jorge Galindo-Villegas 1 1 Department of Genomics. Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway O-01 The evolutionary particularity of expanded immune gene families in mussel and their relationship with functional speciﬁcity Amaro Saco 1§ , Marco Gerdol 2 , Magalí Rey-Campos 1 , Beatriz Novoa 1 , Antonio Figueras 1 1 Institute of Marine Research (IIM), Spanish National Research Council (CSIC), Eduardo Cabello, 6, 36208, Vigo, Spain. 2 Department of Life Sciences, Universit a degli Studi di Trieste, Via Licio Giorgieri 5, 34127 Trieste, Italy. Abstract Transcriptomic studies performed under different infection models have revealed the implication of conserved innate immune gene families in the defensive response of mussels. Many of those families are however greatly expanded in comparison with phylogenetically close species. We have deepened in the evolutionary and selection processes that gave rise to these gene families, particularly the pro-inﬂammatory interleukin IL-17 and the immune Toll-like receptors (TLRs). Comparative genomics was applied to examine the evolution of these genes from poriferans to higher vertebrates. Common evolutionary pat- terns were revealed. Cnidaria was highlighted as the most ancient, diverged phylum and expansions of different magnitude were found as well in other marine bivalves and echinoderm species. Concerning mus- sels, the different clusters obtained in phylogenetic analyses were conserved by the three analyzed species (Mytilus galloprovincialis, M. edulis and M. coruscus). Selection analyses were performed on those clusters/ isoforms and the inter-genomic variation was studied to reveal the degree of conservation of these genes or their subjection to presence/absence variation. Former transcriptomic studies had revealed the implication of TLRs in recognizing bacterial infections in hemocytes and gills, and sub- sequent activation of IL-17 as immune mediators leading to the canonical pathway of NF-kB inﬂammation. For the current study, a massive expression dataset was built using all the transcriptomic data available for mussel (M. galloprovincialis). Clusters of correlated genes were obtained from this dataset. Different expression trends were obtained for different members of the studied gene families. The expression analysis revealed different correlated transcripts that could interact with speciﬁc forms of our target genes in response to different stimuli. These results would point towards a clear functional speciﬁcity that would be allowed by the great underlying variability. Keywords: Mussel, innate immunity, evolution, comparative geno- mics, transcriptomics, IL17, TLR xCorresponding author. E-mail address: asaco@iim.csic.es (A. Saco.) O-02 Characterization of plasma neutralizing factor(s) in shrimp survi- vors from white spot disease outbreak Phasini Buathongkam 1,2,3,x , Jiraporn Srisala 3 , Suparat Taengchaiya- phum 3 , Kallaya Sritunyalucksana 2,3 , Siripong Thitamadee 1,2 1 Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand 2 Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok, Thailand 3 Aquatic Animal Health Research Team, Integrative Aquaculture Biotech- nology Research Group, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Bangkok, Thailand Abstract Our research focuses on the strategy to control white spot syndrome virus infection in shrimp. One approach is to better understand the underlying mechanism of the survivors in the shrimp culture pond post virus outbreak. The survivors were collected from the outbreak farm and subjected to PCR analysis and histological examination. The results revealed variation in WSSV levels among the survivors. In contrast, histological examination demon- strated low degree or none of WSSV inclusions. The naïve shrimp co-cultured with the survivors for 14 days detected WSSV replication by PCR, but without mortality. Injection of survivor plasma with WSSV inoculum into the naïve shrimp cause 10% mortality, whereas those injected with WSSV alone caused 100% mortality of the naïve shrimp within 11 days. The plasma prepared from survivors were found to contain the neutralizing factor(s). The nature of the neutralizing factor in survivor plasma has been characterized and found to be heat-labile. Injection of heat-treated plasma and WSSV inoculum resulted in 100% mortality within 10 days. Shrimp injected with survivor plasma and WSSV demonstrated signiﬁcantly lower copy number of virus, compared to those injected with only WSSV as determined by PCR. The laboratory im- mersion model was established to prepare the plasma survivors and sub- jected to protein proﬁle and small RNA analysis. The RNAi pathway has been reported to play important roles in shrimp antiviral immunity. Our pre- liminary results from proteomic proﬁles of survivor plasma revealed highly expression of the RNase III protein, component of RNAi pathway. The research is on-going. We hope that the results from this study will enable us to design the effective way for combat with white spot disease. Keywords: Shrimp; White spot syndrome virus; Neutralizing factor(s); WSSV survivors; RNAi x Corresponding author. E-mail address: p.buathongkam@gmail.com O-03 White Spot Syndrome Virus infection was aided in Glutamic- Pyruvic Transaminase Shu-Wen Cheng 1 , Han-Ching Wang 1,2x 1 Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, Taiwan Contents lists available at ScienceDirect Fish & Shellﬁsh Immunology journal homepage: www.elsevier.com/locate/fsi https://doi.org/10.1016/j.fsi.2022.10.042 Fish & Shellﬁsh Immunology 131 (2022) 1286e1311