Comparative Study On The Immune Organization And Related Factors Of Two Different Types Of 3 Month Old Grass Carp

In order to study the consistency between the degree of maturation and specifications of the grass carp in the same period but different breeding conditions,the present study observed the microstructure of the high-density, low-feeding 3-month-old grass carp and common 3-month-old grass carp’s head kidney, kidney, intestine and spleen, and intraperitoneal.And in order to study the effect of the vaccine on the grass carp in different types,this experiment used the intraperitoneal injection of vaccine.Head kidneys, kidneys, intestines and spleens were sampled on days 7 and 14 after injection,and the expression levels of IgM,MHCⅠmRNAs in these tissues were detected through the real-time fluorescence quantitative PCR(RT-PCR).This experiment also observed the distribution of IgM positive cells in different tissues.The results showed that:The development of different tissues of grass carp was slow in high-density,low-feeding 3-month-old grass carp, and the development of the head kidneys, kidneys,intestines and spleens of common 3-month-old grass carp was close to the adult fish.After immunized by Grass carp live vaccine(GCHV-892 strain),the highest expression of IgM appeared in the kidney of common 3-month-old grass carp immunized 14 days(74.51 times,P < 0.01).The relative expression of IgM in head kidney, the kidney, spleen is much higher than that in the intestine.And the relative expression of IgM in head kidney, the kidney, spleen in the same type is higher than that in the intestine.The highest expression of MHCⅠ in head kidney appeared in the high-density, low-feeding 3-month-old grass carp immunized 14 days(12.73 times,P <0.01).The highest expression of MHCⅠin the kidney appeared in the common3-month-old grass carp immunized 14 days(56.02 times,P < 0.01);The highest expression of MHCⅠ in intestines appeared in the high-density,low-feeding3-month-old grass carp immunized 7 days(2.16 times,P >0.05);The highest expression of MHCⅠ in spleens appeared in the common 3-month-old grass carp immunized 14days(12.45 times,P < 0.05).The relative expression of MHCⅠ in head kidney of high-density, low-feeding 3-month-old grass carp had a larger increase,while the relative expression of MHCⅠ in kidneys, intestines and spleens had a smaller increase.And the relative expression of MHCⅠ in different tissues had a larger increase in common 3-month-old grass carp.Head kidneys in different period had the largest number of IgM positive cells.These cells all increased after immunization.IgM in the kidneys of common3-month-old grass carp immunized 14 days had the largest increase.While the head kidneys and spleens of common 3-month-old grass carp immunized 14 days had the larger increase.But the intestines in different period all had a smaller increase.These results showed that there was a big difference between tissues of grass carp in a same period but different breeding conditions,the body size and developmental status had consistency,normal farmed fish is relatively mature, can be immunized.