Histopathology and transcriptome profiling reveal features of immune responses in gills and intestine induced by Spring viremia of carp virus.

ABSTRACT

The immune system of bony fish closely resembles that of mammals, comprising both specific (adaptive) and non-specific (innate) components. Notably, the mucosa-associated lymphoid tissue (MALT) serves as the first line of defense within the non-specific immune system, playing a critical role in protecting these aquatic organisms against invading pathogens. MALT encompasses a network of immune cells strategically distributed throughout the gills and intestines, forming an integral part of the mucosal barrier that interfaces directly with the surrounding aquatic environment. Spring Viremia of Carp Virus（SVCV）, a highly pathogenic agent causing substantial harm to common carp populations, has been designated as a Class 2 animal disease by the Ministry of Agriculture and Rural Affairs of China. Utilizing a comprehensive array of research techniques, including Hematoxylin and Eosin (HE)、Alcian Blue Periodic Acid-Schiff (AB-PAS)、transcriptome analysis for global gene expression profiling and Reverse Transcription-Polymerase Chain Reaction (RT-qPCR), this study uncovered several key findings: SVCV is capable of compromising the mucosal architecture in the gill and intestinal tissues of carp, and stimulate the proliferation of mucous cells both in gill and intestinal tissues. Critically, the study revealed that SVCV's invasion elicits a robust response from the carp's mucosal immune system, demonstrating the organism's capacity to resist SVCV invasion despite the challenges posed by the pathogen.