| Asian swamp eel,Monopterus albus is an important economic fish in China or other Asian countries.However,the rising incidence of bacterial diseases has seriously hindered the development of the Asian swamp eel breeding industry,and the species is highly susceptible to infection by Aeromonas caused scale of death.Therefore,it is extremely necessary to find out the pathogenic pathogen of the onset of Asian swamp eel and to understand the response mechanism of the immune system and its related immune genes in the pathogen.This paper explores the pathogenic pathogen causing the death of Asian swamp eel membranaceus in a farm in Jianli County,Hubei Province,and conducts a drug sensitivity test on pathogenic bacteria.This study provides a reference for clinical diagnosis and scientific prevention of the disease.The pathogenic pathogen is collected from the spleen,heart,liver and intestine of the diseased Asian swamp eel.After purification,the pathogens were identified by morphological observation and 16 S rRNA sequence analysis.The pathogenicity and histological characteristics of the pathogens were determined by artificial infection,and the drug sensitivity was detected by Kirby-Bauer disk diffusion method.A dominant strain was isolated from the liver and intestinal tissues of diseased Asian swamp eel and named JL-01.Morphological observation and 16 S rRNA sequence analysis showed that the pathogen was Aeromonas veronii.The symptoms of artificial regression of healthy Asian swamp eel were the same as those observed under natural infection.The mortality rate caused by artificial infection of Asian swamp eel was 40-80% for 7 consecutive days,and Asian swamp eel died after 2-3 days of infection.Drug susceptibility tests showed that the isolated pathogens were highly sensitive to seven major classes of drugs,including cephalosporins,aminoglycosides,quinolones,tetracyclines(except tetracycline),florfenicol,nitrofurans and sulfonamides.Seven antibiotics such as drugs are highly sensitive.The bacterium is resistant to penicillins(except piperacillin),macrolides,peptides and lincomycins.The histopathological changes of Asian swamp eel membranaceus mainly occur in the liver,intestines and kidneys.The pathogen shows strong pathogenicity to jaundice,causing tissue damage and death.Gentamicin,doxycycline and sulfamethoxazole are recommended for the prevention and treatment of this disease according to the drug sensitivity test and healthy culture regulations.The spleen transcriptome sequencing of Aeromonas hydrophila infected with Asian swamp eel was completed by Illumina platform based on double-end sequencing.This sequencing produced 766.37 million clean data,of which more than 80% of the data were successfully.The reference genome of Astragalus was compared.A total of 1501 different express genes(DEGS)were screened,including 928 up-regulated genes and 573 downregulated genes,and 2111 differentially expressed genes were enriched into three categories of GO(biological processes,cellular components,molecular functions)284 related pathways were found in the KEGG enrichment analysis.Among them,9 genes related to immune response were verified by qPCR for the accuracy of transcriptome data.The differentially expressed genes were identified and classified,and the different express genes of interest were screened.This transcriptome data was validated using fluorescent quantitative PCR.To clarify the signal transduction mechanism of the body's antibacterial immunity,the TLR signaling pathway is first predicted.In this pathway,TLR5 and TLR13 may regulate NF-KB and AP signaling through the MyD88-dependent pathway,thereby stimulating the expression of inflammatory genes downstream to cause inflammatory reactions in the organism.In conclusion,the study provides a preliminary insight into the signal transduction mechanism of Aeromonas hydrophila infection and contributes to the exploration of complex antibacterial immunity. |
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