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This article belongs to the Special Issue Tick-Vaccine and Tick-Control. ; Tick vaccination is an environmentally friendly alternative for tick control, pathogen infection, and transmission. Tick vaccine protection is sometimes incomplete, which may be due to problems in the stability, conformation, and activity of antibodies. This might be related to oxidative stress, but more studies are needed about the possible relationships between oxidative stress and immune function. The objective of this study was to evaluate and compare various serum biomarkers of antioxidant response and oxidative damage in cattle vaccinated with two recombinant antigens, the chimera of Subolesin- BM95 (homologue antigen of BM86)-MSP1a and BM86, and a control consisting in the adjuvant of the vaccines. Cupric reducing antioxidant capacity (CUPRAC), ferric reducing ability of the plasma (FRAP), trolox equivalent antioxidant capacity (TEAC), total thiol concentrations, and uric acid were evaluated in serum to determine the antioxidant response. To evaluate oxidative status, ferrous oxidation-xylenol orange (FOX), total oxidant status (TOS), advanced oxidation protein products (AOPP) and hydrogen peroxide (H2O2) concentrations in serum were determined. In addition, correlations between biomarkers of oxidative stress and antibody titers were evaluated. A significant decrease in all antioxidant biomarkers, with exception of thiol, and also a decrease in the oxidant markers TOS, AOPP and H2O2 was observed in cattle vaccinated with BM86, that also showed the highest antibody titers response whereas no significant differences in any of the biomarkers were detected in the Subolesin-Bm95-MSP1a and control groups. In addition, the dynamics of Cuprac and H2O2 with time showed significant differences between the groups. Although this is a pilot study and the results should be interpreted with caution and corroborated by studies involving a large number of animals, our results indicate that, in our experimental conditions, those vaccines able to induce a lower oxidative stress produce a higher concentration of antigen-specific antibodies. Overall, the results of the study provided information on the behavior of different biomarkers related to antioxidant defense, and the oxidative damage in cattle in response to vaccination. ; This research was funded by Seneca Foundation-Regional Agency for Science and Technology of the Government of Murcia, Spain, grant number 19894/GERM/15 and Marinela Contreras is funded by the Ministerio de Ciencia, Innovación y Universidades, Spain, grant FJC-2018-038277-I. ; Peer reviewed

This is an open access article distributed under the terms of the Creative Commons Attribution License.-- et al. ; 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 rick-ettsial 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 prote-ome contributes information on host-pathogen interactions and provides targets for development of novel control strategies for pathogen infection and transmission. ; This research was supported by MEC, Spain, grant BFU2011-23896 (JF), European Union FP7 ANTIGONE project number 278976 (JF) and Postdok BIOGLOBE, Czech Republic CZ.1.07/2.3.00/30.0032 co-financed by the European Social Fund and the state budget of the Czech Republic (JS). N. Ayllón was funded by Ministerio de Educacion, Cultura y Deporte, Spain. S. Weisheit was supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7-PEOPLE-ITN programme (EU Grant No. 238511). ; Peer Reviewed

[Abstract] Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa) are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB). In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB-) and M. bovis-infected young (TB+) and adult animals with different infection status [TB lesions localized in the head (TB+) or affecting multiple organs (TB++)]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen multiplication and promote survival, facilitating pathogen transmission. ; [Author Summary] Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) are zoonotic pathogens representing a serious health problem for humans and animals worldwide. The life cycle of mycobacteria is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar are natural reservoir hosts for MTBC and a model for mycobacterial infections and tuberculosis. The results of this study broaden our understanding of the molecular epidemiology of zoonotic tuberculosis and fill important gaps in knowledge of this topic. The results suggested that mycobacteria manipulate host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen multiplication and promote survival, facilitating pathogen transmission. As previously reported in other obligate intracellular bacteria, host-mycobacteria interactions probably reflect a co-evolutionary process in which pathogens evolved mechanisms to subvert host response to establish infection, but hosts also evolved mechanisms to limit pathogen infection and promote survival. Subsequently, mycobacteria benefit from host survival by increasing the probability for transmission to continue their life cycle. These results provide relevant information to develop tools to evaluate risks for tuberculosis caused by MTBC and for disease control in humans and animals. ; This research was supported by grants AGL2014-56305 and IPT-2011-0735-010000 from Ministerio de Economía y Competitividad, Spain, and the European Union FP7 ANTIGONE grant 278976 and Horizon 2020 COMPARE Grant 377/14. LMH was supported by a University of Castilla La Mancha (UCLM) fellowship. MV was supported by the Research Plan of UCLM. ; Peer reviewed

This is an open access article distributed under the terms of the Creative Commons Attribution License.-- et al. ; Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly affect humans and animals worldwide. The life cycle of mycobacteria is complex and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Recently, comparative genomics analyses have provided new insights into the evolution and adaptation of the MTBC to survive inside the host. However, most of this information has been obtained using M. tuberculosis but not other members of the MTBC such as M. bovis and M. caprae. In this study, the genome of three M. bovis (MB1, MB3, MB4) and one M. caprae (MB2) field isolates with different lesion score, prevalence and host distribution phenotypes were sequenced. Genome sequence information was used for whole-genome and protein-targeted comparative genomics analysis with the aim of finding correlates with phenotypic variation with potential implications for tuberculosis (TB) disease risk assessment and control. At the whole-genome level the results of the first comparative genomics study of field isolates of M. bovis including M. caprae showed that as previously reported for M. tuberculosis, sequential chromosomal nucleotide substitutions were the main driver of the M. bovis genome evolution. The phylogenetic analysis provided a strong support for the M. bovis/M. caprae clade, but supported M. caprae as a separate species. The comparison of the MB1 and MB4 isolates revealed differences in genome sequence, including gene families that are important for bacterial infection and transmission, thus highlighting differences with functional implications between isolates otherwise classified with the same spoligotype. Strategic protein-targeted analysis using the ESX or type VII secretion system, proteins linking stress response with lipid metabolism, host T cell epitopes of mycobacteria, antigens and peptidoglycan assembly protein identified new genetic markers and candidate vaccine antigens that warrant further study to develop tools to evaluate risks for TB disease caused by M. bovis/M.caprae and for TB control in humans and animals. ; This research was supported by grants AGL2014-56305 and IPT-2011-0735-010000 from Ministerio de Economía y Competitividad, Spain, and the European Union FP7 ANTIGONE grant 278976 and Horizon 2020 COMPARE Grant 377/14. ; Peer Reviewed

Anaplasma phagocytophilum transmembrane and surface proteins play a role during infection and multiplication in host neutrophils and tick vector cells. Recently, A. phagocytophilum Major surface protein 4 (MSP4) and Heat shock protein 70 (HSP70) were shown to be localized on the bacterial membrane, with a possible role during pathogen infection in ticks. In this study, we hypothesized that A. phagocytophilum MSP4 and HSP70 have similar functions in tick-pathogen and host-pathogen interactions. To address this hypothesis, herein we characterized the role of these bacterial proteins in interaction and infection of vertebrate host cells. The results showed that A. phagocytophilum MSP4 and HSP70 are involved in host-pathogen interactions, with a role for HSP70 during pathogen infection. The analysis of the potential protective capacity of MSP4 and MSP4-HSP70 antigens in immunized sheep showed that MSP4-HSP70 was only partially protective against pathogen infection. This limited protection may be associated with several factors, including the recognition of non-protective epitopes by IgG in immunized lambs. Nevertheless, these antigens may be combined with other candidate protective antigens for the development of vaccines for the control of human and animal granulocytic anaplasmosis. Focusing on the characterization of host protective immune mechanisms and protein-protein interactions at the host-pathogen interface may lead to the discovery and design of new effective protective antigens. ; This research was partially supported by the Ministerio de Economia, Industria y Competitividad (Spain) grants AGL2014-56305 and BFU2016-79892-P, the European Union (EU) Seventh Framework Programme (FP7) ANTIGONE project number 278976, and the CSIC grant 201440E098 to Jd. MV and LM were supported by the Research Plan of the University of Castilla-La Mancha (UCLM), Spain. ; Peer Reviewed

MEC, Spain [BFU2011-23896]; European Union [278976]; Postdok BIOGLOBE, Czech Republic [CZ.1.07/2.3.00/30.0032]; European Social Fund; state budget of the Czech Republic; Ministerio de Educacion, Cultura y Deporte, Spain; EU [238511]This research was supported by MEC, Spain, grant BFU2011-23896 (JF), European Union FP7 ANTIGONE project number 278976 (JF) and Postdok BIOGLOBE, Czech Republic CZ.1.07/2.3.00/30.0032 co-financed by the European Social Fund and the state budget of the Czech Republic (JS). N. Ayllon was funded by Ministerio de Educacion, Cultura y Deporte, Spain. S. Weisheit was supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7-PEOPLE-ITN programme (EU Grant No. 238511). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.06Public library scienceSan francisco ; 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.

MEC, Spain [BFU2011-23896]; European Union [278976]; Postdok BIOGLOBE, Czech Republic [CZ.1.07/2.3.00/30.0032]; European Social Fund; state budget of the Czech Republic; Ministerio de Educacion, Cultura y Deporte, Spain; EU [238511]This research was supported by MEC, Spain, grant BFU2011-23896 (JF), European Union FP7 ANTIGONE project number 278976 (JF) and Postdok BIOGLOBE, Czech Republic CZ.1.07/2.3.00/30.0032 co-financed by the European Social Fund and the state budget of the Czech Republic (JS). N. Ayllon was funded by Ministerio de Educacion, Cultura y Deporte, Spain. S. Weisheit was supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7-PEOPLE-ITN programme (EU Grant No. 238511). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.06Public library scienceSan francisco ; 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 ...

MEC, Spain [BFU2011-23896]; European Union [278976]; Postdok BIOGLOBE, Czech Republic [CZ.1.07/2.3.00/30.0032]; European Social Fund; state budget of the Czech Republic; Ministerio de Educacion, Cultura y Deporte, Spain; EU [238511]This research was supported by MEC, Spain, grant BFU2011-23896 (JF), European Union FP7 ANTIGONE project number 278976 (JF) and Postdok BIOGLOBE, Czech Republic CZ.1.07/2.3.00/30.0032 co-financed by the European Social Fund and the state budget of the Czech Republic (JS). N. Ayllon was funded by Ministerio de Educacion, Cultura y Deporte, Spain. S. Weisheit was supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7-PEOPLE-ITN programme (EU Grant No. 238511). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.06Public library scienceSan francisco ; 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.

MEC, Spain [BFU2011-23896]; European Union [278976]; Postdok BIOGLOBE, Czech Republic [CZ.1.07/2.3.00/30.0032]; European Social Fund; state budget of the Czech Republic; Ministerio de Educacion, Cultura y Deporte, Spain; EU [238511]This research was supported by MEC, Spain, grant BFU2011-23896 (JF), European Union FP7 ANTIGONE project number 278976 (JF) and Postdok BIOGLOBE, Czech Republic CZ.1.07/2.3.00/30.0032 co-financed by the European Social Fund and the state budget of the Czech Republic (JS). N. Ayllon was funded by Ministerio de Educacion, Cultura y Deporte, Spain. S. Weisheit was supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7-PEOPLE-ITN programme (EU Grant No. 238511). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.06Public library scienceSan francisco ; 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.

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. ; This research was supported by MEC, Spain, grant BFU2011-23896 (JF), European Union FP7 ANTIGONE project number 278976 (JF) and Postdok BIOGLOBE, Czech Republic CZ.1.07/2.3.00/30.0032 co-financed by the European Social Fund and the state budget of the Czech Republic (JS). N. Ayllon was funded by Ministerio de Educacion, Cultura y Deporte, Spain. S. Weisheit was supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7-PEOPLE-ITN programme (EU Grant No. 238511). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ; Sí

MEC, Spain [BFU2011-23896]; European Union [278976]; Postdok BIOGLOBE, Czech Republic [CZ.1.07/2.3.00/30.0032]; European Social Fund; state budget of the Czech Republic; Ministerio de Educacion, Cultura y Deporte, Spain; EU [238511]This research was supported by MEC, Spain, grant BFU2011-23896 (JF), European Union FP7 ANTIGONE project number 278976 (JF) and Postdok BIOGLOBE, Czech Republic CZ.1.07/2.3.00/30.0032 co-financed by the European Social Fund and the state budget of the Czech Republic (JS). N. Ayllon was funded by Ministerio de Educacion, Cultura y Deporte, Spain. S. Weisheit was supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7-PEOPLE-ITN programme (EU Grant No. 238511). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.06Public library scienceSan francisco ; 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 ...