Epidemiology And Molecular Mechanism Of Chronic Stress Activated Cyprinid Herpesvirus 2

Cyprinus herpesvirus??Cyprinid herpesvirus 2,Cy HV-2?has been widely distributed in China,causing huge losses to crucian carp culture in China,and the incidence of crucian carp in natural waters is very rare,speculating that stress is not possible Ignore the important factors.Studies have shown that chronic stress causes fish immunity to decline,but the molecular mechanism by which stress affects the immune system is not yet clear.To this end,based on the epidemiological investigation of gill hemorrhage,this experiment analyzes the effect of cortisol hormones on viral reactivation,and establishes a chronic stress model to analyze the impact of chronic stress on the body's immune system.Disease prevention and control and stress prevention provide theoretical basis.The main findings are as follows:1. Epidemiological investigation of the correlation analysis between Cy HV-2 level and serum cortisol content in carassius auratusSamples were collected from Jiangsu area and tested for Cy HV-2 level and serum cortisol content.The results showed that the crucian kidney virus load was 10³-10⁸copies/?g DNA.10⁵copies/?g DNA was used as the zero cut-off point to distinguish the viral load level.Compared with the low-toxicity group,we found that individuals with higher viral load had higher serum cortisol hormone levels,and Cy HV-2 load levels were positively correlated with serum cortisol levels.2. Effects of artificial injection of hydrocortisone on viral reactivation and immune-related gene expressionTaking the latently infected carp as the object,the effect of cortisol on virus reactivation was analyzed by combining the injection of hydrocortisone with the change of viral load,the content of serum cortisol hormone and the expression level of immune genes.The results showed that after 7 days of continuous cortisone injection,the serum cortisol content of crucian carp increased,and the expression of key genes such as POMC/GR/CRF HPI axis was up-regulated.The expression levels of IFN-?and IL-10 were significantly increased.These results prove that cortisol can reactivate the virus and activate the immune system.Artificial simulation of chronic stress reduces fish immunity3. Artificial simulation of chronic stress reduces fish immunityTaking healthy carp as an object,a chronic stress model was established by simulating operating stress in fishing.Combined with behavioral indicators,physiological indicators and molecular indicators to comprehensively evaluate the chronic stress model.The results showed that the stress group crucian carp dehydration struggle time and phototaxis reaction time were lower than the control group,the behavior was slow and insensitive to light response;serum cortisol content and blood glucose were similar,both increased on the 7th day,14th and 21st day It decreased to similar to the level of the control group and increased on the 28th day;the expression analysis of key genes of stress axis showed that POMC/CRF/GR were all up-regulated.To challenge the chronic stress crucian carp,artificially inject 10⁵(0.1 times LD₅₀)copy number,and count the mortality.The results show that compared with the control group,the mortality rate of the stress group is higher than that of the control group,which proves that the body is more sensitive to external pathogens after stress,resulting in a higher mortality rate.4. Chronic stress crucian carp transcriptome analysisThe molecular mechanism of stress-induced down-regulation of immune system was analyzed by chronic stress crucian carp transcriptomics.The results showed that chronic stress crucian carp Th1 type cytokines were inhibited and Th2 type cytokines were up-regulated.And more Th2 cells are more dominant,which makes the body's immune system disordered and reduces the body's immunity.In order to further understand the relationship between stress and T cell differentiation,we focused on the insulin signaling pathway.The results showed that the pathway was down-regulated and the insulin receptor gene was down-regulated,which caused the body's ability to metabolize blood glucose and affected cell differentiation,which in turn affected immune levels.