Transcriptome Reveals Molecular Characteristics and Immune Response in Triploid Cyprinid Fish Infected with a Novel Pathogenic Aeromonas sp. AS1-4.

Triploid cyprinid fish (TCF, 3N = 150) is a novel hybrid fish showing great disease resistance during aquaculture processes. However, the majority of Aeromonas strains act as opportunistic pathogens that can cause a variety of diseases and pose a notable health risk. In this investigation, a novel Aeromonas sp. AS1-4 was retrieved from the spleen (SPL) of moribund cyprinid fish. Whole genome sequencing (WGS) was employed to characterize its virulence features and signal regulation. Thereafter, TCFs were infected with strain AS1-4 for pathological analysis. Strain AS1-4 challenge could cause abnormal glycogen deposition in the liver (LIV) of TCFs, accompanied by significant alteration of physiological response. Furthermore, expression patterns of pivotal immune-related genes were markedly elevated in TCFs post-infection. Transcriptomic analysis revealed that strain AS1-4 infection may exert a profound impact on insulin signaling pathway and steroid biosynthesis. These results may contribute to the comprehension of molecular characteristics in fish infected with Aeromonas sp. AS1-4.