Protective Effect Of Recombinant Proteins Of Cronobacter Sakazakii During Pregnancy On The Offspring

Cronobacter sakazakii belongs to Enterobacteriacea,which is a common opportunistic food-borne pathogen,widely exists in food,usually with milk powder products as the main carrier.Infants and newborns are the main population infected by C.sakazakii.It can cause severe bacteremia,necrotizing enteritis and meningitis and other serious diseases,and it is extremely easy to cause death after presenting clinical symptoms.At present,how to prevent the infection of the pathogen is significant to the health of newborns.Since infants and young children are the main target group of C.sakazakii,it is considered that maternal immunity can enhance the protection for newborns.In our previous study,immunoproteomic analysis showed that immune GroEL and OmpX exhibiting high expressing levels and strong immune reactions in C.sakazakii,suggesting their potentials as vaccine candidates.In this study,the protective effect of GroEL and OmpX on the suckling rats after vaccinating the pregnant rats using the two proteins was evaluated.Details are as follows,recombinant vectors contained the genes coding for GroEL and OmpX were constructed in this study.The recombinant GroEL and OmpX proteins were expressed in Escherichia coli BL21 and purified as immunogen.The pregnent rats were subcutaneously immunized on the 5th and 15th day of gestation respectively.Three days after birth,the offspring were challenged by infection with C.sakazakii to determine the protective effect of maternal immunity on the offspring.The results showed that immunization during pregnancy decreased bacterial load in the brain and blood,reduced brain and intestine damage,and significantly increased specific antibody titers in the offsprings.Immunization with OmpX increased IL-4 and immunization with GroEL increased IFN-?,suggesting they induced Th2 immune response and Thl immune response respectively.However,although immune response was induced by both the proteins,only the offspring of the OmpX or OmpX/GroEL mixture immunized pregnant rats showed delayed death occurrence,suggesting that OmpX had more effective vaccine protection than GroEL.This study firstly proved that contaction of C.sakazakii proteins during pregnancy could improve the offspring's ability to resist this pathogen caused infection,which provided a potential way to control the damage caused by C.sakazakii.