Efficacy of inactivated Coxiella burnetii against dengue virus infection in mice
SUN Chang-jian;CHEN Mei-ling;WANG Xi-le;YANG Xiao;WEN Bo-hai
Institute of Microbiology and Epidemiology; Academy of Military Medical Sciences; State Key Laboratory of Pathogen and Biosecurity; Beijing 100071; China
Abstract：Objective To asses the efficacy of the Q fever vaccine against dengue virus infection. Methods The inactivated Coxiella burnetii (whole cell vaccine, WCV) was used to immunize BALB/c mice. For primary immunization, 50ug WCV per mouse was subcutaneously injected and 20ug WCV per mouse was intraperitoneally injected at Weeks 5 and 7 after primary immunization, respectively. One week after the last immunization, each mouse was challenged with 105 TCID50 of dengue virus via administration through the tail vein. The mice were sacrificed and blood and brain samples were collected 48 or 72 h after viral challenge. Samples were then examined by real-time quantitative PCR specific to dengue virus. Results In real-time quantitative PCR assay of blood samples, the amount of virus 72h post-infection was significantly lower than that observed at 48h and no significant difference was found between immunized mice and non-immunized mice. The amount of virus in brain samples from both non-immunized and immunized mice at 48h post infection was very low, however the amount of virus in brain samples from non-immunized mice rose sharply and was significantly higher than that of immunized mice at 72h postinfection.Conclusion Non-specific immunoresponses against dengue vuvs infection may be induced by inactivated C. burnetii in mice.
