Immunopotentiation Analysis Of Bifidobacterium Based Vaccine Expression ETEC Cfa/ⅰto OVA

Enterotoxigenic Escherichia coli are are mianly important reason of diarrheal disease in the developing country and travelers who come these areas.ETEC can induce many human diarrheal disease every year.many infants and children death.especially developing country.The bacterial diarrhea is very easy happened by fecal-oral route of ETEC.Although we can heal diarrheal disease by antibiotic therapy,the persister make diarrheal disease uselessly.So we need a safety and effective ETEC vaccine to precaution.ETEC research of genetically engineering vaccine already retain major progress.According to previous research, there are two causative agent caused diarrheal disease, obtain colonization factor antigens and enterotoxins. When the host were infected by ETEC, colonization factor antigens adhere to endothelial cells of the host small intestinal. Then colonization factor antigens produce enterotoxins by establishment and generate. And so far ,fimbrial antigen contain CFA/I,CFA/ II,CFA/ IV. CFA/I is a family dominant serological type , CFA/I can stop causative agent settle down the host small intestinal to cause diarrheal disease, so CFA/I is a very important ingredient of many vaccine.Objective: We want to confirm immunopotentiation of a bifidobacterium based vaccine expression ETEC CFA/I to OVA by immunize SD rats with OVA. Compare with natural bifidobacterium at the same time to observe difference between of them, then observe the distribution of antibody secreting cell in the jejunal mucosa, submucosa, lumen of gland and so on.Methods: (1)Immunizing SD rat by recombined bifidobacterium–CFA/I vaccine. the rats were randomly placed in five groups of 12: group 1:PBS, group 2: OVA, group 3: bifidobacterium, group 4: pBES- CFA/I +OVA, group 5: pBES-LTB+OVA. The above groups of rats were immunized intragastricly four times at 0d, 7d ,14dand 21d. After every group is immunized, collect about 3cm jejunum to systematic analysis the location of sIgA with immunohistochemistry technology and Qwin image manipulation system, research the effect of injecting ovalbumin and bifidoacterium sitmultaneously to sIgA positive cell in the jejunum of the immune SD rats in different time.(2)Blood and fecal pellets were collected from rats at 0d, 7d, 14d and 21d . Specific antibodies were observed in sera and fecal pellets of rats by ELISA.(3) At 28d, randomly draw off 3 rats from PBS,pBES- CFA/I +OVA and pBES-LTB+OVA. Hypodesis the jejunum 4 segments after narcotization,per section 3.0 cm, then inject 0.2 ml ETEC 10407 and 0.2 ml depurated LT to obserove engorge situation of the jejunal and to detect immunopotentiation.Results:(1) SD rats generate specific sIgA after immunity. the SIgA antibodies titer from the pBES-CFA/I +OVA and pBES-LTB+OVA were found to be significantly greater (P<0.05) than from the other three groups(2) pBES-CFA/I+OVA and pBES-LTB+OVA induced strong serum IgG and fecal IgA. The serum IgG and fecal IgA antibody from pBES-CFA/I+OVA and pBES-LTB+OVA were significantly greater (P<0.05) than the antibody from other groups; But there were no very greater (P>0.05) between the other three groups .(3) In the experiment of ansa interstinalis tests , the SD rats got a significant protection, which immunized pBES-CFA/I+OVA and pBES-LTB+OVA. But the other three groups had no protection. Conclusion:These initial experiments suggest that pBES-CFA/I vaccine and OVA could effectively induce the function of immunologic immunopotentiation by intestine mucosal immune. Enhance vaccines effective.