An mRNA vaccine induces antimycobacterial immunity by activating DNA damage repair and autophagy

Effective vaccines are urgently needed for the control of tuberculosis (TB). Here, we report that a mRNA TB vaccine is highly effective and exhibits both prophylactic and therapeutic activities in the zebrafish model of TB. Adult zebrafish immunized with the mRNA vaccine survived significantly longer than the DNA vaccine after Mycobacterium marinum challenge, and post-infection treatment with the mRNA vaccine drastically reduced the bacterial burden. The mRNA vaccine activated multiple DNA break repair systems that are essential for the normal development and function of adaptive immunity, but not the canonical DNA damage responses that promote cell death, demonstrating a profound connection between DNA damage repair and the activation of immune responses under physiological processes of immunization. Remarkably, the mRNA vaccine induced autophagy in granulomas, coinciding with bacterial killing and cell survival. Collectively, these findings demonstrate that the mRNA vaccine elicits potent innate and adaptive immunity, conferring effective host protection against mycobacterial challenge. Overall design: To understand the immune protective mechanisms mediated by the L3T vaccine, we performed RNA-seq analysis of kidneys isolated from zebrafish immunized with the mRNA vaccine and the LPP control. For mRNA vaccination, mRNA candidate vaccines were injected with 1µg LPP-mRNA in the dorsal muscle using PV830 Pneumatic PicoPump microinjector (World Precision Instruments, Sarasota, FL), negative control zebrafish were immunized with LPP-GFP mRNA, immunized twice with two-week intervals (week 0 and 2).After 12 days of the final immunization, kidneys from 5 zebrafish were pooled as one sample and three samples (total 15 kidneys) collected for each group were subjected to RNA-seq analysis. Comparative gene expression profiling analysis of RNA-seq data for L3T mRNA immunized group and its vector control immunized group (LPP-GFP mRNA immunized group).