Establishment of an effective and uniform vaccine development strategy is key to conquering current and emerging infectious diseases. Despite successes against an array of bacterial agents, current approaches to vaccine development are as diverse as the microbes they target and require adjuvants that often have limited efficacy and/or toxic side effects. As a consequence, vaccine discovery is often slow, inefficient, and unsuccessful in the case of many high priority pathogens. The present disclosure suggests that vaccine generation for bacterial pathogens can be improved by optimizing the efficiency of processing/presentation of a bacterial immunogen via the targeting of immunogen to CR2 and/or TLR2 on APCs. This approach not only yields an adjuvant-free mucosal vaccine against a Category A biothreat agent, but also establishes a novel genetic approach/platform for vaccine development, which is applicable to many other infectious agents, thereby profoundly impacting preventive medicine/public health.