Yersinia pestis Adhesins’ Role in Yop Delivery to Neutrophils and Bacterial Survival Using the Neutrophil-like Cell Line HL-60

Abstract

Yersinia pestis is a gram-negative, bacillus bacteria that is the causative agent of the bubonic plague. This strain of Yersinia has been responsible for killing millions of people in history, most notably during the Justinian plague where 25% of the European population was killed. The deadly nature of Y. pestis can be traced to the mechanisms it utilizes. Y. pestis uses a type 3 secretion system (T3SS) to confer cytotoxicity by delivering Yersinia outer proteins (YOPs) to host cells via its needle-like apparatus. In addition to YOPs, Yersinia Pestis has adhesins that attach on the outer membrane and help in docking onto the host cell. The goal of this study was to understand the role of adhesins in the delivery of YOPs to a neutrophil-like cell line HL-60s. The adhesins of interest include Adhesion and Invasin locus (Ail), Plasminogen activator (Pla), and pH-6 antigen (PsaA). This study utilized fluorescence microscopy as well as image cytometry to analyze the effect these adhesins had on YOP delivery. The experiments conducted in this study showed that the adhesins had a positive effect on YOP delivery while having a diminished effect in the presence of serum. Results from this study and previous studies done on the role of adhesins in YOP delivery serve as basis for future studies regarding genetic manipulation and determining critical pathways that can provide clues on how to control Yersinia Pestis.