Genomics and Applied Biology 2024, Vol.15, No.2, 89-98 http://bioscipublisher.com/index.php/gab 92 4.3 Case study: application of gene transfer in improving immune responses A notable case study involves the use of Sargassum polycystumand nucleotides in the diet of juvenile whiteleg shrimp (Litopenaeus vannamei) to improve their immune response and cold tolerance. The study demonstrated that shrimp fed with a diet supplemented with both Sargassum polycystum and nucleotides exhibited significant improvements in survival, growth, and feed utilization indices (Figure 1). Additionally, the nonspecific immune responses, such as phagocytosis, lysozyme, phenoloxidase, and superoxide dismutase (SOD) activity, were markedly enhanced. The upregulation of immune-related genes, including cMnSOD, Penaeidin4, and heat shock protein70 (HSP70), further underscores the effectiveness of gene transfer in bolstering the immune system of shrimp (Abdel-Rahim et al., 2021). 4.4 Exploring cellular pathways using transgenic shrimp Transgenic shrimp serve as valuable models for exploring cellular pathways and understanding the molecular mechanisms underlying various physiological processes. For example, the use of Sargassum horneri extracts in shrimp diets has been shown to stimulate innate immunity and enhance growth performance. The study revealed significant modulation of immune-related genes, such as prophenoloxidase I, prophenoloxidase II, peroxinectin, α2-macroglobulin, clotting protein, lysozyme, superoxide dismutase, and glutathione peroxidase, in shrimp fed with Sargassum horneri extracts (Lee et al., 2020). These findings highlight the potential of transgenic shrimp in elucidating the roles of specific genes and pathways in immune responses and growth regulation. 5 Advances in Gene Transfer Technology 5.1 Innovations in delivery systems Recent advancements in gene transfer technology have significantly improved the efficiency and specificity of gene delivery systems in shrimp. One notable innovation is the development of a VP28-pseudotyped baculovirus expression system, which has demonstrated high infection efficiency in adult shrimp tissues such as gill, heart, and intestine, while showing tissue-specific tropism (Wu et al., 2021). Additionally, the improvement of lentivirus-mediated gene transfer systems, incorporating envelope proteins VP19 and VP28 from the white spot syndrome virus (WSSV), has enhanced the infectivity and tropism of lentiviruses in shrimp cells, achieving higher infection efficiencies compared to traditional methods (Chen et al., 2018). Furthermore, the use of biodegradable nanocarriers resembling extracellular vesicles has emerged as a promising approach for efficient gene delivery, achieving near 100% efficiency in various cell types, including primary cells (Tarakanchikova et al., 2019) (Figure 2). These innovations highlight the potential of advanced delivery systems to revolutionize gene transfer in shrimp. Figure 1 Evaluation of Sargassum polycystum and nucleotide-supplemented diets on immune response and cold tolerance in juvenile white leg shrimp, Litopenaeus vannamei, over a 56-day feeding trial (Adapted from Abdel-Rahim et al., 2021)
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