Preparation And Application Of Bursin

Abstract Two methods was used to prepara bursin. The first one ,bursin was preparaed by solid-phase peptide synthesis corresponding to bursin amino acid sequence Lys-His-Gly-NH2.The synthetic bursin was determined by high-performance liquid chromatography (HPLC)~. capillary electrophoresis (CE) and amino acid analysis. Its purity could reach more than 94 percent. And the second one, bursin was extracted from bursa of fabricius of chickens by superftlter with l000Da filter. The extraction was identified by thin-layer chromatography(TLC) and HPLC. The concentration of bursin in superfiltered fluid was 2.871mg/mI and 2.399mg/mi worked out from the peak area of thin-layer and high-performance liquid chromotographic spectrum respectively. Twenty one-day-old SPF chickens were simultaneously vaccinated subcutaneously with oil-emulsion vaccine of IBDV propagated through CEF or embryo and injected intramuscularly with different dosages bursin, which was prepared and purified from chicken bursa of fabricius by superfilter with I000Da filter. These results suggest that natural bursin can shorten the time of antibody against IBDV induced by IBDV oil- emulsion vaccine, raise the level of serum antibody. AGP titers of the group of high dosage (O.8ml)bursin- vaccine of IBDV were higher than immune control group about 2 titers averagely. Twenty one-day-old SPF chicken were inoculated with IBDV live vaccine mixed with the different dosages of lyophilized bursin by the eye drop method. These findings suggest that bursin can shorten the time of antibody against IBDV induced by IBDV live vaccine, raise the level of antibody, alleviate the lesion of IBDV live vaccine to bursa of fabricius and promote the repairation of the lesion. The AGP antibody titers of the group of middle dosage (O.4m1)bursin- IBDV live vaccine were higher than immune control group about 2 titers averagely. Forty five-day-old famale rabbits were simultaneously inoculated subcutaneously with inactivated vaccines of rabbit hemorrhagic disease virus (RHDV) and injected intramuscularly with different dosages avian bursin, which was obtainted by the same way as used above. The results show that bursin can promote immune response of rabbit vaccinated, The HI titers of antibody against RHDV induced by RHDV inactivated vaccine in the group of high dosage bursin are higher than control about 2-3 titer averagely, but the result of T-lymphocyte transformation assay shows that the bursin can temporarilly enhance the T-lymphocyte transformation.Serial findings suggest that as immunopotentiator,the effect of bursin has a relation to its dosage, but has no relation to the difference of interspecies and the way of into the body. The results of effects of bursin on body weight gain and feed conversion ratio in animals show that the O.4m1 dosage bursin can increase growth of chickens inoculatd with IBDV live vaccine 19% as compared with control and the increased body weight gains of the group of chickens inoculatd with vaccine of IBDV propagated through CEF was 60 higher than control by 7.23% and body weight of the group of 4ml dosage bursin can increased by 13% over the control in rabbit in two months postvaccination. There were higher feed conversion ratio in this two dosage groups than that of control. These results show that the effect of promoting growth of bursin has dosage dependence and has no interspecific difference.