ABSTRACT
Q fever is a worldwide zoonosis and vaccination is the best measure to against its prevalence.Coxiella burnetii (Cb) is an obligate intracellular pathogen responsible for Q fever.Inactivated phase I Cb (Whole cell vaccine,WCV) can provide 100％ protection against Q fever,but its side effect of vaccination is strong.Phase I Cb is treated with chloroform-methanol or trichloroacetic acid and the chloroform-methanol residual (CMR) or the trichloroacetic acid extract (TCA) is used to substitute for WCV.Both CMR and TCA vaccine retain the protective efficient of WCV and significantly reduce the side effects.However,both CMR and TCA vaccine are required to isolate and purify Cb from chick embryos where Cb grows in a biosafety laboratory with the complex procedures.In recent 10 years,the scientists have investigated from protective antigens to CD4+ and CD8+ T cell epitopes of Cb,expecting that the genes encoding the T cell epitopes express highly and induce an efficient protection against Q fever in bodies.