The overall objective of our research is geared towards a better understanding of arthropod-borne diseases in general and plague in particular. Plague is a flea-borne re-emerging zoonosis caused by the bacterium Yersinia pestis. Plague is still a worldwide public health issue accentuated by the emergence of multiply-antibiotic resistant strains of Y. pestis and the potential criminal release of this highly virulent bacterium. Our recent investigation of how Y. pestis adapts to the immune response and other host factors in the infected lymph node has revealed that Y. pestis has to resist to antimicrobial molecules that are secreted by PMNs in infected tissues in addition to inhibit phagocytosis. Our project aims at 1) improving existing therapies and developing new therapeutics against plague and 2) identifying new molecular mechanisms used by Y. pestis to evade immune responses.