| Common carp(Cyprinus carpio)is one of the main species of freshwater fish culture in China and the main economic edible fish in China.However,with the rapid development of carp breeding industry,it not only brings economic development,but also brings serious ecological and environmental problems and uncoordinated development in other aspects.The frequent outbreak of carp diseases has also brought huge economic losses to farmers.Among them,carp spring viremia is one of the most serious diseases,but there is a lack of immune related research on carp anti-virus infection.In this study,the Ig D heavy chain gene of carp was cloned,identified and analyzed,and the phylogenetic tree of immunoglobulin gene of carp was constructed;Fluorescence quantitative PCR(q PCR)was used to detect the expression level of carp immunoglobulin gene in different tissues;In addition,we successfully constructed the model of carp infected with Cyprinus carpio viremia virus(SVCV)by intraperitoneal injection,detected the histopathological changes of skin,gill and intestine before and after SVCV infection,and explored the expression of immune related genes in carp after SVCV infection.The main contents and results of this test are as follows:1.Based on the carp transcriptome database on NCBI,the full-length c DNA sequence of carp Ig D heavy chain gene was cloned and analyzed.The results showed that the Ig D sequence was composed of 2813 bp and contained a 2460 bp open reading frame,which was predicted to encode 819 amino acids.The carp Ig D heavy chain gene consists of a variable region(VH),seven constant regions(CH1-CH7)and a transmembrane region(TM).The phylogenetic tree of carp immunoglobulin system shows that carp Igs gene first converges with blunt snout bream and then with grass carp,which reveals that carp has a very close genetic relationship with Cyprinidae.Subsequently,the m RNA expression level of carp Igs in various tissues was detected.The results showed that the expression of carp Ig D was higher in system tissues.Ig M was highly expressed in head kidney,and Ig Z1 and Ig Z2 were highly expressed in head kidney and spleen.2.The infection model of carp injected intraperitoneally with SVCV was successfully constructed.The results showed that the skin and gill of carp had obvious morphological changes after SVCV infection.Compared with the control group,the skin epidermal layer became thinner day 1 after infection;The secondary gills became shorter and thicker,but there was no significant change in the gut.3 After SVCV infection,many immune related genes in carp skin,gills,intestine and spleen were up-regulated in varying degrees,especially antiviral genes,which reached the peak at day 7.More importantly,we studied the m RNA expression of carp Igs gene after infection with SVCV.The results showed that the expression of Ig D in spleen,gills and skin increased significantly after carp infected with SVCV,suggesting that Ig D may play a role in both system and mucosal tissues.On the contrary,Ig M was significantly up-regulated only in systemic tissues(spleen),but not in mucosal tissues,suggesting that Ig M may be the main immunoglobulin in systemic immunity.For Ig Z1 and Ig Z2,high expression was found in the gut after SVCV infection,which means that they play a more important role in mucosal immunity.However,the specific effects of these Igs still need to be further studied. |
