Prokaryotic Expression And Immunogenicity Analysis Of Outer Membrane Protein Gene OmpH And ArgR Of Coxiella Burnetii

Coxiella burnetii was the pathogen of a world distributed zoonotic disease-Query Fever, which spread in the form of aerosol as a bioterrorism agent. Query fever vaccination is the most effective prevention of Coxiella burnetii infection. The outer membrane protein of Coxiella burnetii is an important protective antigen. The present hottest outer membrane proteins are27kDa,30kDa,34kDa, which all have good immunogenicity. Whereas OmpH and ArgR were newly discovered two Q fever outer membrane proteins in recent years,and they may be used to detect Q fever endocarditis as molecular indexes.In this study, the gene fragments of OmpH and ArgR were firstly amplified respectively by PCR from genome of Coxiella burnetii NineMiles, and then cloned and sequenced. The recombinant prokaryotic expression plasmids pET-32a-OmpH and PGEX-6P-1-ArgR were constructed respectively by the recombination of gene OmpH/ArgR and prokaryotic expression plasmid pET-32a/PGEX-6P-1. The recombinant prokaryotic expression plasmids were then transformed into competent cells BL21(DE3). After the expression of the interested proteins induced by IPTG, the bacteria were ultrasonic crushed to get supernatant and pellet, which were then subjected to SDS-PAGE. The page result of pellet samples showed two interested bands of39.0kDa (OmpH) and41.0kDa (ArgR), indicating that these two proteins were expressed in the form of inclusion bodies. The inclusion bodies of protein OmpH and ArgR were subcutaneously injected respectively to immune6-week old BALB/c female mice, which were immuned once every two weeks later. After the third to fourth immunization, tail blood was collected. Indirect ELLSA method is applied to determined the antibody titer. The serum antibody titer of OmpH protein reached29×100, while the serum antibody titer of ArgR protein was up to211×100, which proved that the two proteins have good immunogenicity to induce the body to produce specific humoral immunity, and can be taken as candidate molecules for Query Fever vaccine.