| Research Abstract |
So far, only two genes (the comI for a 27 kDa outer membrane protein and the htpB for a heat shock protein) encoding protein antigens have been identified and characterized in Coxiella burnetii cloning. At present study, 5 novel immunogenic protein (53, 50, 47, 34 and 24 kDa) encoding genes were cloned and characterized, also the immune protectivities of the recombinant proteins were evaluated.
The sucB gene has an ORF consisting of 1,212 bp encodes a protein of 405 amino acids, which shows 54.3 and 54 % homology, but the N-terminal amino acid sequence shows 45.5 and 42 % homolog) with E.coli and H.influenzae ODH, respectively. The recombinant protein reacted with antisera from Nine Mile phase I immunized rabbit and infected mice, and sera from patients with Q fever. The icd gene has an ORF encodes a protein of 427 amino acids with a predicted molecular mas of 46.6 kDa, which showed high homology of 74 and 73 % with the IDH of E.coli and S.enterica, respectively. The IDH production in E
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.coli DEK2004 transformants harboring the icd gene was high when the clone was grown at low pH of 5 to 5.5 suggests that the icd gene may have a role in the adaptation of the organism to the harsh acidic environment. The 24 kDa outer membrane protein encoding gene has an ORF encodes a protein of 209 amino acids with a predicted molecular mass of 23.88 kDa. The recombinant protein showed specific reaction with anti-C.burnetii serum. The 53 kDa protein encoding gene has an ORF encodes a protein of 469 amino acids with a predicted molecular mass of 52.7 kDa. The recombinant protein reacted with antisera from Nine Mile phase I immunized rabbit and infected mice. The 53 kDa protein resistant to proteinase K treatment but sensitive to periodate treatment suggests it is a glycoprotein. The 34 kDa protein encoding gene has a ORF encodes a protein of 305 amino acids with a predicted molecular mass of 33.6 kDa. Deduced amino acid sequence of the encoded protein includes a putative leader sequeuce of 26 amino acids and the sequence recognized by the signal peptidase suggest it is a membrane associated protein.
The immune protectivities of the purified recombinant proteins were evaluated in guinea pigs. However, the proteins did not show significant protectivity to C.burnetii in guinea pigs. Futher studies need to evaluate the other protein vaccine candidates in both a mouse and guinea pig. Less
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