scholarly journals Anaplasma phagocytophilum Has a Functional msp2 Gene That Is Distinct from p44

2004 ◽  
Vol 72 (7) ◽  
pp. 3883-3889 ◽  
Author(s):  
Quan Lin ◽  
Yasuko Rikihisa ◽  
Suleyman Felek ◽  
Xueqi Wang ◽  
Robert F. Massung ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Anaplasma Phagocytophilum ◽  
Ixodes Scapularis ◽  
Outer Membrane Proteins ◽  
Gene Families ◽  
Single Copy ◽  
The United States ◽  
Granulocytic Anaplasmosis ◽  
The United Kingdom ◽  
Membrane Protein Gene

ABSTRACT The msp2 and p44 genes encode polymorphic major outer membrane proteins that are considered unique to the intraerythrocytic agent of Anaplasma marginale and the intragranulocytic agent of Anaplasma phagocytophilum, respectively. In the present study, however, we found an msp2 gene in A. phagocytophilum that was remarkably conserved among A. phagocytophilum strains from human granulocytic anaplasmosis (HGA) patients, ticks, and a horse from various regions in the United States, but the gene was different in a sheep isolate from the United Kingdom. The msp2 gene in the A. phagocytophilum strain HZ genome was a single-copy gene and was located downstream of two Ehrlichia chaffeensis omp-1 homologs and a decarboxylase gene (ubiD). The msp2 gene was expressed by A. phagocytophilum in the blood from HGA patients NY36 and NY37 and by A. phagocytophilum isolates from these patients cultured in HL-60 cells at 37°C. The msp2 gene was also expressed in a DBA/2 mouse infected by attaching ticks infected with strain NTN-1 and in a horse experimentally infected by attaching strain HZ-infected ticks. However, the transcript of the msp2 gene was undetectable in A. phagocytophilum strain HZ in SCID mice and Ixodes scapularis ticks infected with strain NTN-1. These results indicate that msp2 is functional in various strains of A. phagocytophilum, and relative expression ratios of msp2 to p44 vary in different infected hosts. These findings may be important in understanding roles that Msp2 proteins play in granulocytic ehrlichia infection and evolution of the polymorphic major outer membrane protein gene families in Anaplasma species.

scholarly journals Expression of Multiple Outer Membrane Protein Sequence Variants from a Single Genomic Locus of Anaplasma phagocytophilum

2003 ◽  
Vol 71 (4) ◽  
pp. 1706-1718 ◽  
Author(s):  
A. F. Barbet ◽  
P. F. M. Meeus ◽  
M. Bélanger ◽  
M. V. Bowie ◽  
J. Yi ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Disease Transmission ◽  
Anaplasma Phagocytophilum ◽  
Outer Membrane Proteins ◽  
The United States ◽  
Variable Regions ◽  
Genomic Expression ◽  
Expression Site

ABSTRACT Anaplasma phagocytophilum is the causative agent of an emerging tick-borne zoonosis in the United States and Europe. The organism causes a febrile illness accompanied by other nonspecific symptoms and can be fatal, especially if treatment is delayed. Persistence of A. phagocytophilum within mammalian reservoir hosts is important for ensuring continued disease transmission. In the related organism Anaplasma marginale, persistence is associated with antigenic variation of the immunoprotective outer membrane protein MSP2. Extensive diversity of MSP2 is achieved by combinatorial gene conversion of a genomic expression site by truncated pseudogenes. The major outer membrane protein of A. phagocytophilum, MSP2(P44), is homologous to MSP2 of A. marginale, has a similar organization of conserved and variable regions, and is also encoded by a multigene family containing some truncated gene copies. This suggests that the two organisms could use similar mechanisms to generate diversity in outer membrane proteins from their small genomes. We define here a genomic expression site for MSP2(P44) in A. phagocytophilum. As in A. marginale, the msp2(p44) gene in this expression site is polymorphic in all populations of organisms we have examined, whether organisms are obtained from in vitro culture in human HL-60 cells, from culture in the tick cell line ISE6, or from infected human blood. Changes in culture conditions were found to favor the growth and predominance of certain msp2(p44) variants. Insertions, deletions, and substitutions in the region of the genomic expression site encoding the central hypervariable region matched sequence polymorphisms in msp2(p44) mRNA. These data suggest that, similarly to A. marginale, A. phagocytophilum uses combinatorial mechanisms to generate a large array of outer membrane protein variants. Such gene polymorphism has profound implications for the design of vaccines, diagnostic tests, and therapy.

scholarly journals Porin Activity of Anaplasma phagocytophilum Outer Membrane Fraction and Purified P44

2006 ◽  
Vol 189 (5) ◽  
pp. 1998-2006 ◽  
Author(s):  
Haibin Huang ◽  
Xueqi Wang ◽  
Takane Kikuchi ◽  
Yumi Kumagai ◽  
Yasuko Rikihisa
Keyword(s):  
Outer Membrane ◽  
Anaplasma Phagocytophilum ◽  
Antigenic Variation ◽  
Transmembrane Domain ◽  
Outer Membrane Proteins ◽  
Hypervariable Region ◽  
Tca Cycle ◽  
Metabolic Intermediates ◽  
Host Cytoplasm ◽  
Granulocytic Anaplasmosis

ABSTRACT Anaplasma phagocytophilum, an obligatory intracellular bacterium that causes human granulocytic anaplasmosis, has significantly less coding capacity for biosynthesis and central intermediary metabolism than do free-living bacteria. Thus, A. phagocytophilum needs to usurp and acquire various compounds from its host. Here we demonstrate that the isolated outer membrane of A. phagocytophilum has porin activity, as measured by a liposome swelling assay. The activity allows the diffusion of l-glutamine, the monosaccharides arabinose and glucose, the disaccharide sucrose, and even the tetrasaccharide stachyose, and this diffusion could be inhibited with an anti-P44 monoclonal antibody. P44s are the most abundant outer membrane proteins and neutralizing targets of A. phagocytophilum. The P44 protein demonstrates characteristics consistent with porins of gram-negative bacteria, including detergent solubility, heat modifiability, a predicted structure of amphipathic and antiparallel β-strands, an abundance of polar residues, and a C-terminal phenylalanine. We purified native P44s under two different nondenaturing conditions. When reconstituted into proteoliposomes, both purified P44s exhibited porin activity. P44s are encoded by approximately 100 p44 paralogs and go through extensive antigenic variation. The 16-transmembrane-domain β-strands consist of conserved P44 N- and C-terminal regions. By looping out the hypervariable region, the porin structure is conserved among diverse P44 proteins yet enables antigenic variation for immunoevasion. The tricarboxylic acid (TCA) cycle of A. phagocytophilum is incomplete and requires the exogenous acquisition of l-glutamine or l-glutamate for function. Efficient diffusion of l-glutamine across the outer membrane suggests that the porin feeds the Anaplasma TCA cycle and that the relatively large pore size provides Anaplasma with the necessary metabolic intermediates from the host cytoplasm.

scholarly journals Structure of the Expression Site Reveals Global Diversity in MSP2 (P44) Variants in Anaplasma phagocytophilum

2006 ◽  
Vol 74 (11) ◽  
pp. 6429-6437 ◽  
Author(s):  
Anthony F. Barbet ◽  
Anna M. Lundgren ◽  
A. Rick Alleman ◽  
Snorre Stuen ◽  
Anneli Bjöersdorff ◽  
...  
Keyword(s):  
United States ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Anaplasma Phagocytophilum ◽  
Animal Species ◽  
The United States ◽  
Genomic Locus ◽  
Global Diversity ◽  
Expression Site

ABSTRACT Anaplasma phagocytophilum, a recently reclassified bacteria in the order Rickettsiales, infects many different animal species and causes an emerging tick-borne disease of humans. The genome contains a large number of related genes and gene fragments encoding partial or apparently full-length outer membrane protein MSP2 (P44). Previous data using strains isolated from humans in the United States suggest that antigenic diversity results from RecF-mediated conversion of a single MSP2 (P44) expression site by partially homologous donor sequences. However, whether similar mechanisms operate in naturally infected animal species and the extent of global diversity in MSP2 (P44) are unknown. We analyzed the structure and diversity of the MSP2 (P44) expression site in strains derived from the United States and Europe and from infections of different animal species, including wildlife reservoirs. The results show that a syntenic expression site is present in all strains of A. phagocytophilum investigated. This genomic locus contained diverse MSP2 (P44) variants in all infected animals sampled, and variants also differed at different time points during infection. Although similar variants were found among different populations of U.S. origin, there was little sequence identity between U.S. strain variants (including genomic copies from a completely sequenced U.S. strain) and expression site variants infecting sheep and dogs in Norway and Sweden. Finally, the possibility that combinatorial mechanisms can generate additional diversity beyond the basic donor sequence repertoire is supported by the observation of shared sequence blocks throughout the MSP2 (P44) hypervariable region in reservoir hosts. These data suggest similar genetic mechanisms for A. phagocytophilum variation in all hosts but worldwide diversity of the MSP2 (P44) outer membrane protein.

scholarly journals Immunization with Ehrlichia P28 Outer Membrane Proteins Confers Protection in a Mouse Model of Ehrlichiosis

2011 ◽  
Vol 18 (12) ◽  
pp. 2018-2025 ◽  
Author(s):  
Patricia A. Crocquet-Valdes ◽  
Nagaraja R. Thirumalapura ◽  
Nahed Ismail ◽  
Xuejie Yu ◽  
Tais B. Saito ◽  
...  
Keyword(s):  
T Cells ◽  
Membrane Proteins ◽  
Immune Responses ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
The United States ◽  
Mononuclear Phagocytes ◽  
Specific Cell ◽  
Content Type ◽  
Ifn Γ

ABSTRACTThe obligately intracellular bacteriumEhrlichia chaffeensisthat resides in mononuclear phagocytes is the etiologic agent of human monocytotropic ehrlichiosis (HME). HME is an emerging and often life-threatening, tick-transmitted infectious disease in the United States. Effective primary immune responses againstEhrlichiainfection involve generation ofEhrlichia-specific gamma interferon (IFN-γ)-producing CD4+T cells and cytotoxic CD8+T cells, activation of macrophages by IFN-γ, and production ofEhrlichia-specific antibodies of the Th1 isotype. Currently, there are no vaccines available against HME. We evaluated the ability of 28-kDa outer membrane proteins (P28-OMP-1) of the closely relatedEhrlichia muristo stimulate long-term protective memory T and B cell responses and confer protection in mice. The spleens of mice vaccinated withE. murisP28-9, P28-12, P28-19, or a mixture of these three P28 proteins (P28s) using a DNA prime-protein boost regimen and challenged withE. murishad significantly lower bacterial loads than the spleens of mock-vaccinated mice. Mice immunized with P28-9, P28-12, P28-19, or the mixture inducedEhrlichia-specific CD4+Th1 cells. Interestingly, mice immunized with P28-14, orthologs of which inE. chaffeensisandE. canisare primarily expressed in tick cells, failed to lower the ehrlichial burden in the spleen. Immunization with the recombinant P28-19 protein alone also significantly decreased the bacterial load in the spleen and liver compared to those of the controls. Our study reports, for the first time, the protective roles of theEhrlichiaP28-9 and P28-12 proteins in addition to confirming previous reports of the protective ability of P28-19. Partial protection induced by immunization with P28-9, P28-12, and P28-19 againstEhrlichiawas associated with the generation ofEhrlichia-specific cell-mediated and humoral immune responses.

scholarly journals Genetic Similarity of Gonococcal Homologs to Meningococcal Outer Membrane Proteins of Serogroup B Vaccine

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Henju Marjuki ◽  
Nadav Topaz ◽  
Sandeep J. Joseph ◽  
Kim M. Gernert ◽  
Ellen N. Kersh ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Vaccine Development ◽  
Membrane Vesicle ◽  
Outer Membrane Proteins ◽  
The United States ◽  
Cross Protection ◽  
Outer Membrane Vesicle ◽  
Content Type ◽  
Sequence Identity

ABSTRACT The human pathogens Neisseria gonorrhoeae and Neisseria meningitidis share high genome identity. Retrospective analysis of surveillance data from New Zealand indicates the potential cross-protective effect of outer membrane vesicle (OMV) meningococcal serogroup B vaccine (MeNZB) against N. gonorrhoeae. A licensed OMV-based MenB vaccine, MenB-4C, consists of a recombinant FHbp, NhbA, NadA, and the MeNZB OMV. Previous work has identified several abundantly expressed outer membrane proteins (OMPs) as major components of the MenB-4C OMV with high sequence similarity between N. gonorrhoeae and N. meningitidis, suggesting a mechanism for cross-protection. To build off these findings, we performed comparative genomic analysis on 970 recent N. gonorrhoeae isolates collected through a U.S surveillance system against N. meningitidis serogroup B (NmB) reference sequences. We identified 1,525 proteins that were common to both Neisseria species, of which 57 proteins were predicted to be OMPs using in silico methods. Among the MenB-4C antigens, NhbA showed moderate sequence identity (73%) to the respective gonococcal homolog, was highly conserved within N. gonorrhoeae, and was predicted to be surface expressed. In contrast, the gonococcal FHbp was predicted not to be surface expressed, while NadA was absent in all N. gonorrhoeae isolates. Our work confirmed recent observations (E. A. Semchenko, A. Tan, R. Borrow, and K. L. Seib, Clin Infect Dis, 2018, https://doi.org/10.1093/cid/ciy1061) and describes homologous OMPs from a large panel of epidemiologically relevant N. gonorrhoeae strains in the United States against NmB reference strains. Based on our results, we report a set of OMPs that may contribute to the previously observed cross-protection and provide potential antigen targets to guide the next steps in gonorrhea vaccine development. IMPORTANCE Gonorrhea, a sexually transmitted disease, causes substantial global morbidity and economic burden. New prevention and control measures for this disease are urgently needed, as strains resistant to almost all classes of antibiotics available for treatment have emerged. Previous reports demonstrate that cross-protection from gonococcal infections may be conferred by meningococcal serogroup B (MenB) outer membrane vesicle (OMV)-based vaccines. Among 1,525 common proteins shared across the genomes of both N. gonorrhoeae and N. meningitidis, 57 proteins were predicted to be surface expressed (outer membrane proteins [OMPs]) and thus preferred targets for vaccine development. The majority of these OMPs showed high sequence identity between the 2 bacterial species. Our results provide valuable insight into the meningococcal antigens present in the current OMV-containing MenB-4C vaccine that may contribute to cross-protection against gonorrhea and may inform next steps in gonorrhea vaccine development.

scholarly journals PCR–RFLP of outer membrane proteins gene of Dichelobacter nodosus: a new tool in the epidemiology of footrot

1999 ◽  
Vol 122 (3) ◽  
pp. 521-528 ◽  
Author(s):  
S. C. GHIMIRE ◽  
J. R. EGERTON
Keyword(s):  
Outer Membrane ◽  
Protein Gene ◽  
Outer Membrane Proteins ◽  
Small Ruminants ◽  
Phenotypic Characteristics ◽  
Dichelobacter Nodosus ◽  
Source Of Infection ◽  
Pcr Rflp ◽  
Different Strains ◽  
Membrane Protein Gene

Currently only phenotypic epidemiological markers, serogrouping and virulence testing of Dichelobacter nodosus, are available for investigating footrot outbreaks in small ruminants. These methods have limitations in tracing the source of infection. In this study, a genotypic marker, PCR–RFLP of outer membrane protein gene, was used to characterize D. nodosus. The technique was evaluated in a controlled experiment involving two strains of bacteria. PCR–RFLP was found to be highly specific in differentiating isolates obtained from recipient animals infected with different strains. Subsequently, this technique was used to characterize isolates obtained from field cases of footrot in Nepal. A total of 11 patterns was recognized among 66 Nepalese D. nodosus isolates representing four different serogroups. PCR–RFLP also discriminated isolates with similar phenotypic characteristics. However, all isolates which, phenotypically, were virulent were represented by only two patterns irrespective of their serogroups. It is suggested that PCR–RFLP described here could be a useful epidemiological marker in the study of footrot.

scholarly journals An Ixodes scapularis protein required for survival of Anaplasma phagocytophilum in tick salivary glands

2006 ◽  
Vol 203 (6) ◽  
pp. 1507-1517 ◽  
Author(s):  
Bindu Sukumaran ◽  
Sukanya Narasimhan ◽  
John F. Anderson ◽  
Kathleen DePonte ◽  
Nancy Marcantonio ◽  
...  
Keyword(s):  
Gene Expression ◽  
United States ◽  
Salivary Glands ◽  
Anaplasma Phagocytophilum ◽  
Ixodes Scapularis ◽  
The United States ◽  
Salivary Protein ◽  
Specific Requirement ◽  
Obligate Intracellular ◽  
Tick Salivary Glands

Anaplasma phagocytophilum is the agent of human anaplasmosis, the second most common tick-borne illness in the United States. This pathogen, which is closely related to obligate intracellular organisms in the genera Rickettsia, Ehrlichia, and Anaplasma, persists in ticks and mammalian hosts; however, the mechanisms for survival in the arthropod are not known. We now show that A. phagocytophilum induces expression of the Ixodes scapularis salp16 gene in the arthropod salivary glands during vector engorgement. RNA interference–mediated silencing of salp16 gene expression interfered with the survival of A. phagocytophilum that entered ticks fed on A. phagocytophilum–infected mice. A. phagocytophilum migrated normally from A. phagocytophilum–infected mice to the gut of engorging salp16-deficient ticks, but up to 90% of the bacteria that entered the ticks were not able to successfully infect I. scapularis salivary glands. These data demonstrate the specific requirement of a pathogen for a tick salivary protein to persist within the arthropod and provide a paradigm for understanding how Rickettsia-like pathogens are maintained within vectors.

scholarly journals Human Granulocytic Anaplasmosis: First Reported Case in Canada

2009 ◽  
Vol 20 (3) ◽  
pp. e100-e102 ◽  
Author(s):  
Michael D Parkins ◽  
Deirdre L Church ◽  
Xiu Yan Jiang ◽  
Daniel B Gregson
Keyword(s):  
United States ◽  
Anaplasma Phagocytophilum ◽  
The United States ◽  
Rickettsial Infection ◽  
Human Granulocytic Anaplasmosis ◽  
Tick Activity ◽  
Granulocytic Anaplasmosis ◽  
Blood Neutrophils ◽  
Rickettsial Diseases ◽  
Elevated Transaminases

Human granulocytic anaplasmosis (HGA) is a tick-borne rickettsial infection of peripheral blood neutrophils caused byAnaplasma phagocytophilum. While this infection is increasingly recognized as endemic throughout much of the United States, no Canadian cases have been previously described, despite the agent being identified in Canadian ticks. Herein we present a case of HGA acquired in an urban Alberta centre. Canadian physicians must be aware of the possibility of tick-borne rickettsial diseases as etiology of fever in individuals presenting with leukopenia/lymphopenia, thrombocytopenia and elevated transaminases during periods of tick activity. Prompt recognition and treatment are important in minimizing resultant morbidity and mortality.

scholarly journals Proteomic Identification of a Novel Anaplasma phagocytophilum DNA Binding Protein That Regulates a Putative Transcription Factor

2007 ◽  
Vol 189 (13) ◽  
pp. 4880-4886 ◽  
Author(s):  
Xueqi Wang ◽  
Takane Kikuchi ◽  
Yasuko Rikihisa
Keyword(s):  
Transcription Factor ◽  
Outer Membrane ◽  
Anaplasma Phagocytophilum ◽  
Promoter Region ◽  
Outer Membrane Proteins ◽  
Hypothetical Protein ◽  
Etiologic Agent ◽  
Major Protein ◽  
Mobility Shift ◽  
Putative Transcription Factor

ABSTRACT Anaplasma phagocytophilum, the etiologic agent of human granulocytic anaplasmosis, is an obligatory intracellular bacterium. Little is known about the gene regulatory mechanisms for this bacterium. A gene encoding a putative transcription factor, tr1, upstream of three tandem genes encoding outer membrane proteins, including the major outer membrane protein P44, is driven by a strong promoter. In the present study, gel mobility shift assays revealed the presence of A. phagocytophilum proteins that interact with the promoter region of tr1. These proteins interacting with the tr1 promoter region were purified by biotin-labeled DNA affinity chromatography from a large amount of host cell-free bacteria. Mass spectrometry identified the major protein as an A. phagocytophilum 12.5-kDa hypothetical protein, which was named ApxR. In a DNase I protection assay, recombinant ApxR (rApxR) bound cooperatively to four 24- or 25-bp sites within 235 bp upstream of tr1: regions III and IV proximal to tr1 had higher affinity than regions I and II did. Deletion assays showed that regions III and IV were essential for rApxR binding, whereas regions I and II upstream of regions III and IV were not. The primary cis-acting region was region IV, since region IV alone was sufficient for rApxR to strongly transactivate the downstream gene in a lacZ reporter assay. Addition of regions I, II, and III did not enhance transactivation. These results show that ApxR is a novel transcriptional regulator that directly regulates tr1.

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