Heat Shock Proteins in Vector-pathogen Interactions: The Anaplasma phagocytophilum Model

Abstract

Anaplasma phagocytophilum is an emerging zoonotic pathogen that is transmitted by Ixodes ticks and causes human granulocytic anaplasmosis. Several recent studies have shown that tick infection by A. phagocytophilum induces com- plex changes mediated by different mechanisms such as remodeling of cytoskele- ton, inhibition of cell apoptosis, modification of metabolism and cell epigenetics, manipulation of the immune response and stress response. In particular, heat shock proteins (Hsp), a group of highly conserved proteins, play an important role in tick- pathogen interactions. Not only tick Hsp mediate the response to A. phagocytophi- lum infection, but also bacterial Hsp bind tick and vertebrate host cells. Herein, we reviewed the literature and provided new insides on the role of bacterial and tick Hsp in tick-pathogen interactions. We combined the analysis of published data on genomics, transcriptomics and proteomics of the response of Ixodes scapularis ticks to A. phagocytophilum infection. In addition, functional studies were conducted to test some of the hypotheses on the role of tick Hsp in response to A. phagocyto- philum infection. These results provide a more comprehensive view of the major Hsp involved in the response to pathogen infection in ticks.