Immunomodulatory Effects Of Bacterial Genomic DNA On Crucian Carp

In mice and humans, B cells, antigen-presenting cells (APCs) including monocytes, macrophages and dendritic cells and natural killer (NK) cells can be stimulated directly or indirectly by the bacterial DNA and oligodeoxynucleotides (ODNs) containing the CpG dinucleotides (CpG DNA or immunostimulatory sequence, ISS ). Preview studies have showed that bacterial DNA containing the CpG dinucleotides, virus, plasmid DNA can enchance fish innate immune response such as producing antivirus cytokines and antibody. But up to now, whether these bacterial genomic DNA can enchance fish innate immune response in vivo has not been reported yet.In the present study, Ecoli DH5 a genomic DNA containing much the CpG dinucleotides is employed to investigate whether oral and injection administration of bacterial genomic DNA into Crucian carp (Carassius auratus) can enhances fish immune response. The results demonstrate i.p.-injected l(k 2CK 40ug fish"1 genomic DNA into Crucian carp {Carassius auratus) can enchance fish innate immune response at day 3, which is characterized by the accumulation of neutrophils, total leucocyte of peripheral blood, lysozyme and bactericialdal activity offish serum. But compared with i.p.-injected 20, 40ug fish"1 genomic DNA , i.p.-injected lOug fish"' genomic DNA Crucian carp (Carassius auratus) enchance fish innate immune response most.And further results demonstrate i.p.-injected 10ug fish"1 genomic DNA into Carassius auratus can upgrade the number of neutrophils, total leucocytes of peripheral blood, lysozyme and bactericialdal activity offish serum at day 3, and also upgrade the number of lymphocytes at day 6 and upgrade all the above immune response index at day 9, however, not any immune response exists at day 30.The immune response to oral administration of fish immunostimulants is much more important in acquculture. Present studies also demonstrate that the immune response to oral administration of 5~40u.g fish"1 genomic DNA for a day appears no significant difference with those of the control group at day three. And further results demonstrate oral administration of 20ug fish"1 genomic DNA for a week can upgrade the number of neutrophils, lymphocytes and total leucocytes of peripheral blood, lysozyme and bactericialdal activity of fish serum at day three, and upgrade all the above immune response index except the number of lymphocytes at day 7,but a little decrease when compared with those index at day 3.