Identification and Characterization of Anaplasma phagocytophilum Proteins Involved in Infection of the Tick Vector, Ixodes scapularis

• Published in: PloS one Vol. 10; no. 9; p. e0137237
• Main Authors: Villar, Margarita, Ayllón, Nieves, Kocan, Katherine M, Bonzón-Kulichenko, Elena, Alberdi, Pilar, Blouin, Edmour F, Weisheit, Sabine, Mateos-Hernández, Lourdes, Cabezas-Cruz, Alejandro, Bell-Sakyi, Lesley, Vancová, Marie, Bílý, Tomáš, Meyer, Damien F, Sterba, Jan, Contreras, Marinela, Rudenko, Nataliia, Grubhoffer, Libor, Vázquez, Jesús, de la Fuente, José
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 04.09.2015; Public Library of Science (PLoS)
• Subjects: Anaplasma; Anaplasma phagocytophilum; Anaplasmosis; Animal biology; Animals; Arachnids; Bacteria; Bacterial infections; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biology; Causes of; Cell culture; Chaperonin 60 - genetics; Chaperonin 60 - metabolism; Disease transmission; Female; Gastrointestinal Tract - microbiology; Gene expression; Gene Expression Profiling; Gene Expression Regulation; Genetic aspects; Health sciences; Host-parasite relationships; Host-Pathogen Interactions; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; Hsp70 protein; Hypotheses; Immunology; Infections; Ixodes - microbiology; Ixodes scapularis; Life Sciences; Membrane Proteins - genetics; Membrane Proteins - metabolism; Molecular Sequence Annotation; Parasitology; Pathogens; Physiological aspects; Product differentiation; Protein biosynthesis; Protein synthesis; Proteins; Proteome - genetics; Proteome - metabolism; Proteomics; Replicative form; Rickettsiae; Rickettsiales; Salivary gland; Salivary glands; Salivary Glands - microbiology; Signal Transduction; Stress; Stress response; Stress, Physiological; Stresses; Ticks; France; Czech Republic; United Kingdom > UK; United States > US; Oklahoma; Spain
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0137237

Anaplasma phagocytophilum is an emerging zoonotic pathogen transmitted by Ixodes scapularis that causes human granulocytic anaplasmosis. Here, a high throughput quantitative proteomics approach was used to characterize A. phagocytophilum proteome during rickettsial multiplication and identify proteins involved in infection of the tick vector, I. scapularis. The first step in this research was focused on tick cells infected with A. phagocytophilum and sampled at two time points containing 10-15% and 65-71% infected cells, respectively to identify key bacterial proteins over-represented in high percentage infected cells. The second step was focused on adult female tick guts and salivary glands infected with A. phagocytophilum to compare in vitro results with those occurring during bacterial infection in vivo. The results showed differences in the proteome of A. phagocytophilum in infected ticks with higher impact on protein synthesis and processing than on bacterial replication in tick salivary glands. These results correlated well with the developmental cycle of A. phagocytophilum, in which cells convert from an intracellular reticulated, replicative form to the nondividing infectious dense-core form. The analysis of A. phagocytophilum differentially represented proteins identified stress response (GroEL, HSP70) and surface (MSP4) proteins that were over-represented in high percentage infected tick cells and salivary glands when compared to low percentage infected cells and guts, respectively. The results demonstrated that MSP4, GroEL and HSP70 interact and bind to tick cells, thus playing a role in rickettsia-tick interactions. The most important finding of these studies is the increase in the level of certain bacterial stress response and surface proteins in A. phagocytophilum-infected tick cells and salivary glands with functional implication in tick-pathogen interactions. These results gave a new dimension to the role of these stress response and surface proteins during A. phagocytophilum infection in ticks. Characterization of Anaplasma proteome contributes information on host-pathogen interactions and provides targets for development of novel control strategies for pathogen infection and transmission.