Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ANAPLASMA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
PubMed2003

Serotyping isolates of Anaplasma phagocytophilum by using monoclonal antibodies.

Ten mouse monoclonal antibodies (MAbs) that react with Anaplasma phagocytophilum (the human granulocytic ehrlichiosis agent) Webster isolates were developed. Seven different isolates of A. phagocytophilum were subtyped with these MAbs. Western blot analysis revealed that these MAbs reacted mainly with 41- to 46-kDa Msp2 proteins. Six MAbs reacted with all isolates. Four other MAbs reacted with human isolates from Wisconsin, but not with human isolates from New York or with animal isolates. Three different serotypes were identified. These features may lead to the development of other specific MAbs in order to provide tools for antigenic characterization of human isolates of A. phagocytophilum.

Anaplasma phagocytophilum↗
PubMed2003

Detection of antibodies to Anaplasma phagocytophilum and Ehrlichia chaffeensis antigens in sera of Korean patients by western immunoblotting and indirect immunofluorescence assays.

Two hundred seventy one serum samples from South Korean patients were tested to detect antibodies against Anaplasma phagocytophilum (the human granulocytic ehrlichiosis agent) and Ehrlichia chaffeensis (the human monocytic ehrlichiosis agent) by indirect fluorescent-antibody assay (IFA) and the Western blot assay. These sera were collected from patients with symptoms of high fever. The rate of seropositivity for Orientia tsutsugamushi was 50.9% by IFA at the Public Health & Environmental Research Institute and National Institute of Health in South Korea. By IFA, 30 (11.1%) and 39 (14.4%) of the serum samples reacted with A. phagocytophilum and E. chaffeensis antigens, respectively. By the Western blot assays, 24 (8.9%) and 29 (10.7%) of the serum samples reacted with purified A. phagocytophilum and E. chaffeensis protein antigens, respectively. This report strengthens other evidence regarding the presence of A. phagocytophilum and E. chaffeensis infections in humans in South Korea.

Adult↗
PubMed2004

CXCR2 blockade influences Anaplasma phagocytophilum propagation but not histopathology in the mouse model of human granulocytic anaplasmosis.

Anaplasma phagocytophilum is an obligate intracellular bacterium that infects neutrophils and causes human granulocytic anaplasmosis. Infection induces neutrophil secretion of interleukin-8 or murine homologs and perpetuates infection by recruiting susceptible neutrophils. We hypothesized that antibody blockade of CXCR2 would decrease A. phagocytophilum tissue load by interrupting neutrophil recruitment but would not influence murine hepatic pathology. C3H-scid mice were treated with CXCR2 antiserum or control prior to or on day 14 after infection. Quantitative PCR and immunohistochemistry for A. phagocytophilum were performed and severity of liver histopathology was ranked. Control mice had more infected cells in tissues than the anti-CXCR2-treated group. The histopathological rank was not different between treated and control animals. Infected cells of control mice clustered in tissue more than in treated mice. The results support the hypothesis of bacterial propagation through chemokine induction and confirm that tissue injury is unrelated to A. phagocytophilum tissue load.

Anaplasma phagocytophilum↗
PubMed2005

Unidirectional suppression of Anaplasma phagocytophilum genotypes in infected lambs.

Five-month-old lambs were simultaneously infected with different doses of two 16S rRNA genetic variants of Anaplasma phagocytophilum and thereafter followed for clinical observation and blood sampling. The result of the study indicates a unidirectional suppression of genotypes in infected lambs, at least during a certain period of an A. phagocytophilum infection.

Anaplasma phagocytophilum↗
PubMed2002

Cytokine gene expression by peripheral blood leukocytes in horses experimentally infected with Anaplasma phagocytophila.

Human granulocytic ehrlichiosis (HGE), a tick-borne zoonosis, is caused by an obligatory intragranulocytic bacterium, the HGE agent, a strain of Anaplasma phagocytophila. The equine model of HGE is considered valuable in understanding pathogenic and immune mechanisms of HGE. In the present study, cytokine mRNA expression by peripheral blood leukocytes (PBLs) in horses was examined during the course of infection by intravenous inoculation of A. phagocytophila or by allowing feeding by infected ticks. The p44 genes encoding the major outer membrane protein P44s of A. phagocytophila were detected by PCR in PBLs of all four horses from 4 to 20 days postexposure. During the 20-day infection period, interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) mRNA expression was upregulated in PBLs of all four horses, and IL-8 mRNA expression was upregulated in three horses. Gamma interferon, IL-10, and IL-12 p35 mRNAs were weakly expressed in only one horse each. IL-2, IL-4, IL-6, and IL-12 p40 mRNA expression, however, could not be detected in the PBLs of any of the four horses. These results suggest that IL-1beta, TNF-alpha, and IL-8 generation during A. phagocytophila infection has a primary role in HGE pathogenesis and immunomodulation.

Anaplasma phagocytophilum↗
PubMed2002

Determination of the nucleotide sequences of heat shock operon groESL and the citrate synthase gene (gltA) of Anaplasma (Ehrlichia) platys for phylogenetic and diagnostic studies.

The 1,670-bp nucleotide sequence of the heat shock operon groESL and the 1,236-bp sequence of the citrate synthase gene (gltA) of Anaplasma (Ehrlichia) platys were determined. The topology of the groEL- and gltA-based phylogenetic tree was similar to that derived from 16S rRNA gene analyses with distances. Both groESL- and gltA-based PCRs specific to A. platys were also developed based upon the alignment data.

Anaplasma↗
PubMed2006

Innate immune response to Anaplasma phagocytophilum contributes to hepatic injury.

In mice, Anaplasma phagocytophilum control is independent of phagocyte oxidase (phox), inducible NO synthase (NOS2), tumor necrosis factor (TNF), and MyD88 Toll-like receptor signaling. We show that despite evasion of these host responses, phox, NOS2, TNF, and MyD88 are activated and contribute to inflammation and hepatic injury more than A. phagocytophilum itself.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Structure of the expression site reveals global diversity in MSP2 (P44) variants in Anaplasma phagocytophilum.

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.

Amino Acid Sequence↗
PubMed2006

Selection for simple major surface protein 2 variants during Anaplasma marginale transmission to immunologically naïve animals.

Anaplasma marginale, a rickettsial pathogen, evades clearance in the animal host by antigenic variation. Under immune selection, A. marginale expresses complex major surface protein 2 mosaics, derived from multiple donor sequences. However, these mosaics have a selective advantage only in the presence of adaptive immunity and are rapidly replaced by simple variants following transmission.

Anaplasma marginale↗
PubMed1983

Comparison of proteins synthesized by two different isolates of Anaplasma marginale.

We present results on the initial definition of proteins synthesized by two isolates of Anaplasma marginale. Bovine erythrocytes infected with A. marginale were radioactively labeled with [35S]methionine or a 3H-amino acid mixture during short-term in vitro culture. The labeled proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This technique revealed protein bands of various apparent molecular weights from less than 14,000 to greater than 200,000. The bands observed represented A. marginale proteins because (i) uninfected erythrocytes from the same animal did not incorporate radioisotope during identical culture conditions, and (ii) the incorporation of radioisotope into proteins during culture of infected erythrocytes was inhibited by tetracycline but not by cycloheximide. The radioactive protein profiles of two different isolates of A. marginale, from Washington and Florida, were compared by two-dimensional gel electrophoresis. About 200 proteins were resolved in each case. Several proteins differed in position when the two-dimensional gel maps were compared, indicating variations in protein structure between the two A. marginale isolates.

Anaplasma↗
PubMed1985

Presence of common antigens, including major surface protein epitopes, between the cattle (intraerythrocytic) and tick stages of Anaplasma marginale.

Epitopes of major surface proteins of the intraerythrocytic cattle stage of Anaplasma marginale were demonstrated in the midgut stage of the organism within the infective tick host Dermacentor andersoni. These proteins were common to all A. marginale isolates tested and at all stages of parasitemia. Sera from cattle immunized with the tick midgut stage of A. marginale immunoprecipitated multiple-erythrocyte-stage proteins, as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The major proteins recognized (primarily greater than 14 and less than 200 kilodaltons [kDa]) included two major-erythrocyte-stage surface proteins of 36 and 105 kDa molecular size. To confirm the presence of common tick and erythrocyte A. marginale antigens with the immunized cattle sera, we purified the 36-kDa erythrocyte-stage protein by monoclonal immunoaffinity chromatography and developed an enzyme-linked immunosorbent assay based on the purified protein. All sera from cattle immunized with tick-stage A. marginale and cattle infected with various isolates of A. marginale developed antibodies to the 36-kDa protein. The potential immunoprophylactic, diagnostic, and epidemiologic value of the major epitopes common to both the invertebrate and mammalian stages of A. marginale, especially the 36-kDa protein, is discussed.

Anaplasma↗
PubMed1987

Characterization of an immunoprotective protein complex of Anaplasma marginale by cloning and expression of the gene coding for polypeptide Am105L.

Immunization with an Anaplasma marginale surface protein complex containing two polypeptides (Am105U and Am105L), each having a molecular weight of 105,000, protected cattle against challenge with virulent organisms. These polypeptides were immunoprecipitated together from detergent extracts of A. marginale by a neutralizing monoclonal antibody. After surface radioiodination of intact parasites, both Am105U and Am105L contained the radiolabel. To define the structural and antigenic relationships between Am105U and Am105L and to determine individual efficacies as protective immunogens, we cloned and expressed A. marginale DNA in Escherichia coli. We identified recombinant bacteria which expressed a novel protein of 105,000 molecular weight as a major cellular component. The recombinant protein was structurally and antigenically homologous to Am105L. There were multiple, partially homologous copies of the cloned DNA sequence in the rickettsial genome.

Anaplasma↗
PubMed1988

Immunization of cattle with a 36-kilodalton surface protein induces protection against homologous and heterologous Anaplasma marginale challenge.

Immunization of cattle with a purified Anaplasma marginale major surface protein, AmF36, induced protection against homologous challenge with the Florida isolate. Similarly, immunized cattle were protected from challenge with the antigenically and structurally distinct Washington-O isolate of A. marginale. The degree of protection in AmF36-immunized cattle varied from complete prevention of rickettsemia to significant delay in the onset of rickettsemia compared with control immunized cattle. A single AmF36 vaccinate was not protected against homologous challenge despite development of a strong antibody response. Immunoprecipitation of A. marginale proteins with a monoclonal antibody to AmF36 identified minor molecular size heterogeneity in this protein from different isolates, including the Florida and Washington-O isolates. The apparent molecular size of this surface protein in the Florida isolate was 36 kilodaltons, whereas the analogous proteins in Washington-O and four other isolates of A. marginale from the United States had molecular masses of 33 to 34 kilodaltons. Significantly, the surface-exposed peptides of these proteins appear to be conserved among the different isolates. These results demonstrate the potential of AmF36 as a subunit immunogen for bovine anaplasmosis and indicate a structural basis for its cross-protective ability.

Anaplasma↗
PubMed1988

Molecular size variations in an immunoprotective protein complex among isolates of Anaplasma marginale.

A major surface protein complex from the Florida isolate of Anaplasma marginale has been previously shown to induce protection in immunized cattle and has been proposed as the basis of a subunit vaccine against anaplasmosis. This complex in the Florida isolate is composed of two noncovalently associated polypeptides with molecular masses of 105 and 100 kilodaltons (kDa). The analogous protein complex from four geographically different isolates of A. marginale was immunoprecipitated and compared with the protein complex of the Florida isolate. The polypeptides of the complex varied in apparent molecular mass among the isolates. By using antibodies recognizing epitopes on each polypeptide of the Florida isolate, the antigenic identity of the polypeptides in the analogous complexes was determined. The polypeptides recognized by the neutralizing monoclonal antibody 22B1, which recognizes a 105-kDa polypeptide in the Florida isolate, ranged from 70 to 100 kDa in the other isolates. Those polypeptides recognized by rabbit antiserum R911, which recognizes a 100-kDa polypeptide in the Florida isolate, ranged from 97 to 100 kDa. The surface-exposed peptides in the complexes were compared by limited enzymatic digestion to assess structural homology among isolates. Despite the marked variations in molecular weight, there were conserved peptides between the 22B1-reactive polypeptides and between the R911-reactive peptides. Determination of the role of the conserved peptides in inducing immunity will be critical in the application of these polypeptides as the basis of a subunit vaccine for bovine anaplasmosis.

Anaplasma↗
PubMed1989

Immunization of cattle with the MSP-1 surface protein complex induces protection against a structurally variant Anaplasma marginale isolate.

The Anaplasma marginale surface protein complex MSP-1 of the Florida isolate is composed of a 105-kilodalton (kDa) polypeptide, which bears a neutralization-sensitive epitope, and a 100-kDa polypeptide. Antigenically similar polypeptides in the Okanogan, Wash. (Washington-O), isolate MSP-1 are 86 and 100 kDa, respectively. Immunization of cattle with Florida isolate MSP-1 induced antibody titers to both MSP-1 polypeptides and protected cattle against homologous and heterologous challenge.

Anaplasma↗
PubMed1990

Cyclic rickettsemia during persistent Anaplasma marginale infection of cattle.

Submicroscopic levels of Anaplasma marginale rickettsemia in persistently infected cattle were determined by using nucleic acid hybridization. Within individuals, the rickettsemia levels steadily increased from less than 10(4) infected erythrocytes per ml to a peak of more than 10(6) infected erythrocytes per ml and then rapidly declined. This logarithmic variation parallels the variation of the rickettsemia level seen in acute infection and suggests that cyclic emergence of antigenic variants is a mechanism of rickettsial persistence.

Anaplasma↗
PubMed1991

The msp1 beta multigene family of Anaplasma marginale: nucleotide sequence analysis of an expressed copy.

A gene for the beta subunit of the immunoprotective surface antigen MSP-1 of Anaplasma marginale was previously cloned and expressed in Escherichia coli. A nucleic acid probe based on this gene detects A. marginale infection in carrier cattle and in the tick vector. We report here the sequence and structural features of the cloned msp1 beta gene and expressed polypeptide. The gene codes for a polypeptide of 756 amino acids that contains domains of tandemly repeated sequence and glutamine-rich regions at the N and C termini. The cloned copy is a member of a multigene family with multiple restriction fragment length polymorphisms in isolates of this rickettsia from different geographical regions. The availability of the sequence will allow use of the polymerase chain reaction in diagnostic assays and the preparation and testing of different vaccine constructs in cattle.

Amino Acid Sequence↗
PubMed1991

Induction of protective immunity by using Anaplasma marginale initial body membranes.

Anaplasma marginale initial bodies of the Norton Zimbabwe strain were disrupted and separated into two membrane fractions banding at 1.15 and 1.22 g/cm3 by sucrose density centrifugation. The membrane fractions differed in their morphology and polypeptide composition. Membranes banding at 1.22 g/cm3 shared epitopes with surface-exposed polypeptides of the Florida strain of A. marginale, confirming the outer membrane location of these polypeptides. Immunization of cattle with either membrane fraction induced protection against homologous challenge, as demonstrated by significantly less anemia and lower peak rickettsemia values compared with those of adjuvant-immunized and nonimmunized calves. Protection correlated with antibody titer to membrane polypeptides. Although both membrane fractions induced protection, a 31-kDa polypeptide was the only common antigen to both fractions, as shown by reactivity of immune sera. Identification of membrane antigens capable of inducing protective immunity should facilitate development of vaccines against anaplasmosis suitable for use in Zimbabwe.

Anaplasma↗