Fusion Of Bursin And Its Effects On Growth And Immune Performance Of Mice

Bursin(BS)is an active small molecule peptide present in the bursa of avian bursae and its structure is lysine-histidine-glycine(Lys-His-Gly-NH2).The research results at home and abroad showed that BS has the function of enhancing immunity and promoting the growth of livestock and poultry.In this study,a fusion 4 peptide BS was designed and synthesized by the specificity of E.coli encoding an external protein,and a piece of fusion peptide was added at the end.Through prokaryotic expression technology,the soluble expression conditions were explored and optimized.At the same time,preliminary studies were conducted on the growth and immune performance of the soluble protein and spheroidin of BS in mice.For the further mass production of BS and further study lay the foundation.1 BS soluble expression and optimization of expression conditions:In this study,BS was designed,synthesized and cloned into pET-32a plasmid.The recombinant plasmid was named as pET-BS.pET-BS was transformed into DH5? for expansion.Plasmids were extracted and sequenced.pET-BS was transformed into BL21(DE3)and induced to express soluble BS protein;After optimizing the conditions of temperature,inducer,pre-induction broth concentration,induction expression time,IPTG concentration and sucrose concentration,simultaneous purification of soluble expressed BS.The results show that:Optimum temperature of BS soluble expression was 24.5?;When sucrose and IPTG were added as inducers,its effect was better than adding IPTG or sucrose separately;The optimal induction time was 10 h;The final concentration of IPTG in induction expression was 24 ?g/mL;The optimal concentration of sucrose induction was 1.0 g/100 mL;By the grope of purification conditions,it could be found that His label protein was well combined with Ni+ in ProteinlsoTM Ni-NTA Resin.In soluble BS protein,With 200 mM imidazole soluble equilibrium solution,the objective BS was completely washed down,and the purification effect of BS was good.2 Effect of BS on the growth and immunity of mice:In this study,complete blank group and normal immune group(normal immune AIV inactivated vaccine)were used as the control group.BS soluble protein and the spheroidin protein were devided into different doses group respectively(intramuscular injection with BS soluble protein by high dose,middle dose and low dose,oral administration with BS spheroidin protein by high dose,middle dose and low dose)to vaccinate KM mice,both BS soluble protein group and BS spheroidin protein group vaccinated together with avian influenza inactivated vaccine.Two weeks after the first immunization vaccinated the second time;After the first immunization day 0 W and the first immunization 1 W,2 W,3 W,4 W and 5 W later weighed all the mice.After the first immunization,each group of 2 W,3 W,4 W and 5 W randomly selected 10 mice(male and female)to collect the whole blood and isolate the serum to detect the antibody.Calculating the immune organ index of thymus and spleen,immune to part for the first time after the 2 W and 5 W to formalin fixation the liver and kidney in mice do HE staining,and the serum AST,ALT,TP,GLB,ALB,BUN,CREA and ALP were detected.The results showed that:The dose of BS muscle injection promoted the growth of mice.The effect of BS oral group on mouse growth was not obvious.The effect of BS on the spleen immune organ index is not obvious to the thymus.HI experiment results show that.The effect of BS muscle injection was not obvious in the early stage of mouse antibody,but it had the effect of maintaining antibody level in the later stage.Hower,BS oral administration has the effect of promoting antibody production in mice in the early stage,but the effects did not have markedly difference.HE experiment and serum liver function and renal function factor test showed,BS was safe for mice,and there was no obvious pathological changes in the liver and kidney of animals,and there was no abnormal function factor.Conclusion:BS plays an important role in promoting the growth of mice and promoting the production of antibodies.BS has good safety performance and no toxic side effects on mice.