| Congresso Brasileiro de Microbiologia 2023 | Resumo: 43-1 | ||||
Resumo:Fish farming represents one of the fastest-growing agribusiness activities in Brazil. However, super-intensive production systems expose animals to stressful situations, which benefit opportunistic pathogens such as Aeromonas hydrophila. These pathogens take advantage of the host's immunosuppression to initiate the disease process by colonizing the skin, degrading tissue, and destroying protein components. To propose control strategies against A. hydrophila, understanding the pathogenesis of the infection at the molecular level, specifically gene expression, is crucial. Thus, the aim of this study was to investigate gene expression mechanisms during A. hydrophila infection in Nile Tilapia (Oreochromis niloticus). The animals were provided by the São Francisco and Parnaíba Valleys Development Company (CODEVASF) and authorized for use by the Animal Ethics Committee (nº 0009/140217). The study adopted a completely randomized design with two treatments: (T1) inoculated with A. hydrophila and (T2) inoculated with saline solution. To induce a stress condition in the animals, the water pH was adjusted to 9.0 for 96 hours, after which the experimental groups were challenged and euthanized at 6 and 24-hour intervals. The skin was removed for RNA extraction, and sequencing was performed using the Illumina NextSeq equipment. The analysis of differential gene expression of the transcriptome in the two groups (T1 and T2) and at 6 and 24 hours was carried out using the R packages EdgeR (6 and 24 hours) and DESeq2 (24 hours). Genes were considered differentially expressed (DGEs) with a p-value ≤ 0.05 and classified as up-regulated and down-regulated when the log2FoldChange was > 1 and < 1, respectively. Among the identified DGEs were regulating synaptic membrane exocytosis 2 (rimS2, 4.033) and macrophage mannose receptor 1 (mrc1B, 3.720). The up-regulated gene (mcr1B) regulates the endocytosis of glycoproteins terminated with mannose or N-acetyl glucosamine. Phagocytosis is a fundamental defense mechanism in bony fish, where during the inflammatory response, macrophages perform phagocytosis through phagocytic receptors or hydrophobic interactions of their membrane with target particles, leading to the release of inflammatory mediators. Furthermore, macrophages are equipped with an arsenal of antimicrobial responses primarily applied to pathogens involved in the phagolysosomes. It was observed that, with a 24-hour infection time, there was increased expression of both mrc1B (3.720) and rimS2 (4.033), indicating that in the skin, melanomacrophage centers are active, promoting phagocytosis, exocytosis, and antigen presentation, which are important defense strategies in Nile Tilapia. In other words, during the initial stage of skin injury caused by trauma, this would be a safety mechanism for the animal. Our study allowed the identification of the biological process of immune response through the analysis of differentially expressed and functional genes. In conclusion, Nile Tilapia utilizes mechanisms of innate immune response against initial skin infections, such as complement factors, cellular hyperplasia, and macrophage action through phagocytosis. Palavras-chave: Fish, RNA-Seq, Tanscriptomics Agência de fomento:This study was conducted with the support of the Coordination for the Improvement of Higher Education Personnel - Brazil (CAPES) - Funding Code 001 | |||||