Immunogenicity and Therapeutic Effects of pVAX1-rv1419 DNA from Mycobacterium tuberculosis

Abstract

Background The situation of tuberculosis (TB) is very severe in China. New therapeutic agents and regimens to treat TB are urgently needed. Objective In this study, a DNA vaccine expressing Mycobacterium tuberculosis (MTB) Rv1419 antigen was constructed and its immunogenicity and therapeutic effects were evaluated. Method Normal mice and TB model mice were immunized intramuscularly three times at two-week intervals with saline, plasmid vector pVAX1, M. vaccae vaccine, pVAX1- ag85a (rv3804c) DNA or pVAX1-rv1419 DNA, respectively. Results At three weeks after the last immunization, flow cytometry showed a higher proportion of CD4+ T cells expressing IFN-y (Th1) in response to Rv1419 protein in blood from the pVAX1- rv1419 DNA group compared with the saline and vector groups (P<0.05), suggesting a predominant Th1 immune response. Live bacterial loads in lungs and spleens were lower by 0.41 log10 in the pVAX1- rv1419 DNA group than in the saline controls. In addition, pathological changes in the lungs of the DNA vaccinated groups were less. These results suggest that pVAX1- rv1419 DNA could be effective for the treatment of TB, significantly increasing the Th1-type cellular immune response, and inhibiting the growth of MTB. Conclusion Therefore pVAX1- rv1419 DNA is a candidate for inclusion in a therapeutic combination DNA vaccine against TB.