Investigating cytokine responses in rats: Genetic immunization against tuberculosis using five Mycobacterium tuberculosis-specific genes

Tuberculosis, being an infectious disease, is unchecked and still hard to wipe out in the underdeveloped countries. Despite ongoing efforts, no new TB vaccine has been successfully developed in the past century beyond BCG, although DNA-based vaccines have shown promise over the last two decades. In this study, five Mycobacterium tuberculosis-specific genes- Rv1908c/KatG, Rv3418c/GroES, Rv0934/PhoS1/PstS, Rv0440/GroEL2 and Rv0350/DnaK-were cloned into the pVAX1 expression vector to construct DNA vaccines. These constructs were evaluated in rats using naked DNA and BCG prime-boost strategies. Forty-five Wistar albino rats were divided into three major groups: DNA vaccine group, BCG prime-boost group and no vaccine control. Post-immunization responses were evaluated through cytokine ELISA for TNF-?, IFN-? and IL-6. Among DNA vaccines, DnaK-pVAX1 and GroES-pVAX1 elicited the strongest cytokine responses, followed by GroEL2-pVAX1 and PstS-pVAX1. The prime-boost groups (especially BCG + DnaK-pVAX1, BCG + GroES-pVAX1 and BCG + cocktail) showed further enhanced responses. Statistical analysis confirmed significant cytokine elevation in vaccinated groups compared to controls (p < 0.05). DNA vaccines, whether used alone or in combination with BCG, show strong potential as immunogenic and therapeutic tools for TB and may help reduce treatment duration in the future.