Construction Of Prokaryotic Expressing Plasmid Of Anti-Cryptosporidium ScFv-PE And Its Kill Action To Cryptosporidium Parvum

Cryptosporidium is a protozoan parasite.It can result incryptosporidiosis which infects both human beings andanimals.Cryptosporidium parvum causes chronic diarrhoea.It,sinfection is through peroral infection mainly. Cryptosporidiosisis one of the common deadly causes in such patients ofimmunodeficiency such as AIDS.In the last years ,on account of watersource polluted, Cryptosporidiosis patients are increasing ,Cryptosporidium result in the number of T cell sharp decrease anddepress immunity. Ninety percent cryptosporidiosis patients recei-ved severe chronic,diarrhoea,liquidstools,Abdominal distention,vomiting,stomach-ache,debilitation,fever.Immunodeficiency theperson who be infect with in the HIV,cryptosporidiosis causessevere chronic diarrhoea even deadly. Up to now two hundreds kindsdrugs be used treat cryptosporidiosis ,but drug withdrawalsymptom recurrence and drug side effect is significant. However,a specific and effective therapy for this opportunistic infectiondoes not yet exist .Targeted drug provide direction forcryptosporidiosis cure. Immunotoxin is a kind of targeted drug. C.parvum dermal film has stabile antigen phenotype,it has ecto-cellperiod in the mammal host internal growth cycle.We can makeConjugate of specific antibody and cello-toxic agent to attackcryptosporidium parvum .With the development of biotechnology,scientis prepare a serial of reconstitute antibody in gene level ,eg,single-chain antibody. Kinds of toxic genetic structure wereidentifed .Through antibody and toxic reforming to reconstructionrecombination toxic. With specificity targeting PE fusion proteinis expressed ,display specific cytotoxicity effect in vitro.In thisstudy,we gain solubility recombination toxic based on inclusionbody form. Avoid denatured protein renaturation process that iselaborate,hyp-efficiency ,high cost.These factors confined expre-ssion product to utilize . The recombinant plasmids were trans-formed into E.coli strain TB1 and induced by IPTG .Recombinantimmunotoxins was highly expressed successfully. After expressionproducts was purificated,we carry out animal experiment.The resultindicated that recombinant immunotoxins PMAL-ScFv-PE is effectivekill action to Cryptosporidium parvum. Construction of prokaryotic expression vector ofanti-cryptosporidium recombinant immunotoxins: anti-cryptosporidium ScFv-PE was amplified by PCR with designed a pair of primersfrom a PET-ScFv-PE recombinant immunotoxins. The primers includeEcoRI and HindIII endonuclease site .The fragment of amplified anda prokaryotic expressing vector PMAL were digested by EcoRI andHindIII , the fragment of amplified was cloned into a prokaryoticexpressing vector PMAL.Then transferred into competent cells ofEscherichia coli(E.coli)DH5a.The positive clones were screened onLB plate with amplicillin.The transformatants were identified byrestriction endoclease digestion ,PCR and the nuleotidesequences.And the recombinant plasmids PMAL-ScFv-PE wasconstructed successfully. Expression of recombinant immunotoxins PMAL-ScFv -PE:Therecombinant plasmids were transformed into E.coli strain TB1 andinduced by IPTG .The recombinant immunotoxins was highlyexpressed successfully at 25℃,1mmol/L IPTG for 3h,.After celllysis and SDS-PAGE analysis,expressed recombinant immunotoxinsScFv-PE take 21% of the total cell proteins.The expression productsmost exist in forms of soluble fraction. In western blots,expressedrecombinant immunotoxins is distinctively recognized a molecule of113 Kda, which was in accord with the one we expected. The expression products were evaluated the cytotoxicity toCryptosporidium parvum : The expression products was purificatedto assess efficacy in vivo.The groups of three four-day-oldsuckling mice were used for experimental inoculations by gastricintubation 1 ×104 Cryptosporidium parvum oocysts.After 48hinfection, two groups of infected mice respectively received0.2mL,0.4mL of supernatants containing recombinantimmunotoxins(170μg/mL)every day for three consecutive days .Asingle group mouse served as an control group,which received TB1with control supernatants as same as recombinant immunotoxinspreparation method.All mice were kill 72h after treated orally,andthe ileum were removed ,fixed in 10% neutral buffered formalin ,thenmake histopathologic examination.The result of histopathologic...