PgtE Enzyme of Salmonella enterica Shares the Similar Biological Roles to Plasminogen Activator (Pla) in Interacting With DEC-205 (CD205), and Enhancing Host Dissemination and Infectivity by Yersinia pestis

Yersinia pestis, the cause of plague, is a newly evolved Gram-negative bacterium. Through the acquisition of the plasminogen activator (Pla), Y. pestis gained the means to rapidly disseminate throughout its mammalian hosts. It was suggested that Y. pestis utilizes Pla to interact with the DEC-205 (CD205) receptor on antigen-presenting cells (APCs) to initiate host dissemination and infection. However, the evolutionary origin of Pla has not been fully elucidated. The PgtE enzyme of Salmonella enterica, involved in host dissemination, shows sequence similarity with the Y. pestis Pla. In this study, we demonstrated that both Escherichia coli K-12 and Y. pestis bacteria expressing the PgtE-protein were able to interact with primary alveolar macrophages and DEC-205-transfected CHO cells. The interaction between PgtE-expressing bacteria and DEC-205-expressing transfectants could be inhibited by the application of an anti-DEC-205 antibody. Moreover, PgtE-expressing Y. pestis partially re-gained the ability to promote host dissemination and infection. In conclusion, the DEC-205-PgtE interaction plays a role in promoting the dissemination and infection of Y. pestis, suggesting that Pla and the PgtE of S. enterica might share a common evolutionary origin.Peer reviewe

Joint Beamforming and Trajectory Design for Aerial Intelligent Reflecting Surface-Aided Secure Transmission

This paper studies the secure transmission challenge confronted with future communication systems. In our considered model, the confidential communication between legitimate users is strengthened by an aerial intelligent reflecting surface (AIRS) deployed on aerial platforms such as an unmanned aerial vehicle (UAV). The average secrecy rate for all time slots is first investigated to improve information security during AIRS flights. Then, the transmit beamforming, phase-shifting matrix, and trajectory of AIRS are jointly designed, aiming to maximize the average secrecy rate performance between legitimate users. On account of the non-convexity of the formulated objective function and the coupled three key variables, we resort to an alternative strategy that converts the original objective into three sub-problems and solves them recursively. In particular, the transmit beamforming is designed on the basis of the generalized eigenvalue optimization method, and the closed-form solution is derived. For the AIRS-related optimization, a Minorization-Maximization (MM)-based algorithm and a deep deterministic policy gradient (DDPG)-based method are proposed to derive the solutions of phase shift matrix and trajectory, respectively. Simulation results show that AIRS assistance can obtain nearly twice the secrecy performance of terrestrial intelligent reflecting surface (TIRS) systems