PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ANAPLASMA”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 595 records · Page 33Linked to original sources
PubMed1982

A case of apparent suppression of Anaplasma marginale infection by eperythrozoonosis (Eperythrozoon teganodes).

The apparent suppression of Anaplasma marginale infection by Eperythrozoon teganodes in a splenectomized calf has been reported. A splenectomized calf, inoculated with 500 ml of blood having 23% erythrocytes infected with A. marginale, developed eperythrozoonosis on the fourth day post inoculation. A. marginale parasitaemia remained very low during the patent eperythrozoonosis. A. marginale parasites started to increase in number only after E. teganodes infection had been controlled with neoarsphenamine. A splenectomized calf treated identically, but not showing E. teganodes parasites in the peripheral blood, developed clinical anaplasmosis and fulminant parasitaemia within 3-4 days post inoculation.

Anaplasmataceae Infections↗
PubMed1988

The oxidant defence system in water-buffaloes (Bubalus bubalis) experimentally infected with Anaplasma marginale.

The glutathione (GSH) -oxidant defence system protects the erythrocytes and leucocytes from oxidative damage. Leucocyte -superoxide dismutase (SOD), GSH-peroxidase (GSH-px), GSH-reductase (GR), GSH-S-transferase (GSH-S-t) and arginase were examined in samples from buffaloes infected with Anaplasma marginale. All the enzymes, except arginase, were also studied in the red cell haemolysates from these animals. GSH-S-t, GSH- and glutathione-reductase (GR) levels in leucocytes decreased in infected animals suggesting a decline in the efficiency of the GSH-oxidant defence system. SOD levels increased but there was no change in leucocyte-arginase activity due to infection. Infection caused no significant changes in red cell SOD, GSH-px, GR and GSH. However, GSH-S-t significantly decreased (P less than 0.05).

Anaplasmosis↗
PubMed1993

Human interferon alpha fails to inhibit the development of Babesia bigemina and Anaplasma marginale infections in cattle.

Studies were undertaken to determine whether human interferon alpha (HuIFN-alpha) administered orally could inhibit the development of clinical disease caused by the intraerythrocytic protozoan Babesia bigemina and the intraerythrocytic rickettsia Anaplasma marginale in cattle. HuIFN-alpha did not inhibit intraerythrocytic multiplication of either of the two parasites, suggesting that there is no role for HuIFN-alpha administered orally in the control of these pathogens.

Anaplasmosis↗
PubMed1997

Anaplasma marginale: effect of the treatment of cattle with an interferon gamma-neutralizing monoclonal antibody or the nitric oxide synthetase inhibitor aminoguanidine on the course of infection.

Cattle undergoing initial infection with the rickettsia Anaplasma marginale were treated with either a monoclonal antibody (MoAb) with neutralizing activity for bovine interferon gamma (IFN-gamma) or aminoguanidine (AG), a specific inhibitor of the inducible form of nitric oxide synthetase (iNOS). Plasma levels of MoAb and AG were measured over the time of administration. The course of A. marginale infection was not altered in the MoAb-treated cattle relative to untreated controls. In cattle treated with AG however, A. marginale infection was significantly ameliorated, as judged by lower parasite levels and decreased anaemia in these cattle relative to the controls. The implications of these findings in relation to the basis for immunity against this economically important haemoparasite are discussed.

Anaplasmosis↗
PubMed2003

Infection exclusion of the rickettsial pathogen anaplasma marginale in the tick vector Dermacentor variabilis.

Anaplasma marginale is a tick-borne, rickettsial cattle pathogen that is endemic in several areas of the United States. Recent studies (J. de la Fuente, J. C. Garcia-Garcia, E. F. Blouin, J. T. Saliki, and K. M. Kocan, Clin. Diagn. Lab. Immunol. 9:658-668, 2002) demonstrated that infection of cultured tick cells and bovine erythrocytes with one genotype of A. marginale excluded infection with other genotypes, a phenomenon referred to as infection exclusion. The present study was undertaken to confirm the phenomenon of infection exclusion of A. marginale genotypes in a tick vector, Dermacentor variabilis. Only one genotype of A. marginale (Virginia isolate) was detected by PCR in ticks that fed first on a calf infected with a Virginia isolate and second on a calf infected with an Oklahoma isolate. These studies demonstrate that infection exclusion of A. marginale genotypes also occurs in naturally infected ticks, as well as in cattle and cultured tick cells, and results in establishment of only one genotype per tick.

Anaplasmataceae↗
PubMed2002

Selective in vivo depletion of CD4(+) T lymphocytes with anti-CD4 monoclonal antibody during acute infection of calves with Anaplasma marginale.

To investigate the in vivo role of CD4(+) T lymphocytes during acute anaplasmosis, thymectomized calves were selectively depleted of CD4(+) T lymphocytes by treatment with anti-CD4 monoclonal antibody (MAb) and were then infected with the Florida strain of Anaplasma marginale in two sequential experiments (experiments 1 and 2). Treatment of thymectomized calves with a total of 5.0 mg of anti-CD4 MAb/kg of body weight during the 1st week followed by 0.3-mg/kg doses administered twice weekly for 7 weeks resulted in significant depletion of CD3(+) CD4(+) and CD4(+) CD45R(+) (naive) T lymphocytes from blood, spleen, and peripheral lymph nodes for the duration of the 8-week study, compared to the results for thymectomized control calves treated with a subclass-matched MAb. All calves became parasitemic and pyretic following experimental infection with A. marginale, and decreases in packed cell volume (PCV) coincided with peak parasitemia. No significant differences in PCV or parasitemia were observed between treatment groups. Thymectomized calves treated with anti-CD4 MAb were able to mount an anti-A. marginale antibody response, although in experiment 2, anti-CD4 MAb-treated calves had four- to sixfold lower immunoglobulin G1 (IgG1) and no detectable IgG2 anti-A. marginale major surface protein 2-specific antibody titers compared to thymectomized control calves treated with a subclass-matched MAb. At the level of CD4(+)-T-lymphocyte depletion achieved and experimental anaplasmosis induced, thymectomized anti-CD4 MAb-treated calves were able to control acute anaplasmosis. This was in contrast to the prediction that significant depletion of CD4(+) T lymphocytes would abrogate resistance to acute infection.

Acute Disease↗
PubMed1998

Expression of Anaplasma marginale major surface protein 2 variants during persistent cyclic rickettsemia.

Anaplasma marginale is an intraerythrocytic rickettsial pathogen of cattle in which infection persists for the life of the animal. Persistent A. marginale infection is characterized by repetitive rickettsemic cycles which we hypothesize reflect emergence of A. marginale antigenic variants. In this study, we determined whether variants of major surface protein 2 (MSP-2), a target of protective immunity encoded by a polymorphic multigene family, arise during persistent rickettsemia. By using a quantitative competitive PCR to identify rickettsemic cycles, msp-2 transcripts expressed in vivo were isolated from peak rickettsemia of sequential cycles. Cloning and sequencing of msp-2 cDNA revealed that genetic variants of MSP-2 emerge representing a minimum of four genetic variant types in each cycle during persistent infection. Two-color immunofluorescence using variant-specific antibody showed that emergence of MSP-2 variants resulted in expression of a minimum of three antigenic types of MSP-2 within one rickettsemic cycle. Therefore immune control of each cycle would require responses to an antigenically diverse A. marginale population. These findings demonstrate that polymorphic MSP-2 variants emerge during cyclic rickettsemia in persistent A. marginale infection and suggest that emergent variants play an important role in persistence.

Amino Acid Sequence↗
PubMed2003

Simultaneous variation of the immunodominant outer membrane proteins, MSP2 and MSP3, during anaplasma marginale persistence in vivo.

Vector-borne bacterial pathogens persist in the mammalian host by varying surface antigens to evade the existing immune response. To test whether the model of surface coat switching and immune evasion can be extended to a vector-borne bacterial pathogen with multiple immunodominant surface proteins, we examined Anaplasma marginale, a rickettsia with two highly immunogenic outer membrane proteins, major surface protein 2 (MSP2) and MSP3. The simultaneous clearance of variants of the two most immunodominant surface proteins of A. marginale followed by emergence of unique variants indicates that the switch rates and immune selection for MSP2 and MSP3 are sufficiently similar to explain the cyclic bacteremia observed during infection in the immunocompetent host.

Amino Acid Sequence↗
PubMed1991

Detection of Anaplasma marginale rickettsemia prior to onset of clinical signs by using an antigen capture enzyme-linked immunosorbent assay.

An antigen capture enzyme-linked immunosorbent assay was developed by using monoclonal antibodies to conserved epitopes on the Anaplasma marginale MSP1a surface protein. The assay sensitivity was 1.1 (+/- 0.5)% parasitized erythrocytes, and all infected cattle were detected prior to development of 2.0%-parasitized erythrocytes. Positive tests preceded the onset of anemia by a mean of 2 days. The assay was specific for anaplasmosis, as demonstrated by nonreactivity with another common hemoparasitic pathogens.

Anaplasmosis↗
PubMed1998

Detection of cattle naturally infected with Anaplasma marginale in a region of endemicity by nested PCR and a competitive enzyme-linked immunosorbent assay using recombinant major surface protein 5.

A competitive enzyme-linked immunosorbent assay using recombinant major surface protein 5 (rMSP5-cELISA) of Anaplasma marginale was validated in a naturally infected cattle herd in an area of eastern Oregon where A. marginale is endemic. The true positive and negative A. marginale infection status of 235 randomly selected cattle was determined by using a nested PCR (nPCR) coupled with msp5 sequence analysis and hybridization. Judgment of the reliability of the nPCR and hybridization for detection of persistent infections was based on three observations. First, the nPCR was able to detect as few as 30 infected erythrocytes per ml. Second, the nPCR was able to consistently detect low levels of rickettsemia in seven carrier cattle experimentally infected with A. marginale. Third, msp5 sequence analysis showed >95% identity among 30 nPCR amplicons from cattle naturally infected with field strains of A. marginale. The nPCR and hybridization identified 151 infected and 84 uninfected cattle among the 235 animals tested. With a cutoff point of 28%, the rMSP5-cELISA showed a sensitivity of 96% and a specificity of 95%. These results indicate that the rMSP5-cELISA can sensitively and specifically detect cattle with naturally acquired persistent A. marginale infections and suggest that it is an excellent assay for epidemiological studies, eradication programs, and regulation of international cattle movement.

Anaplasmosis↗
PubMed1991

Anaplasma marginale in Lepus nigricollis (Blanford) treated with oxytetracycline.

The objective of this study was to test the efficiency and acceptability of oxytetracycline hydrochloride (OTC) in anaplasmosis. Five mg OTC was the only drug given subcutaneous twice by a week to anaplasmotized Lepus nigricollis. The therapeutic results were judged in relation to the parasitized erythrocytes (PE) present, assessment of the clinical acceptability of OTC was perfect in anaplasmosis (Anaplasma marginale).

Journal Article↗
PubMedDate not supplied

[First report of Anaplasma bovis (Donatien and Lestoquard, 1936) Dumler et al. (2001) at micro region of Campos dos Goytacazes, State of Rio de Janeiro, Brazil].

The first report of Anaplasma bovis was pointed out at the micro region of Campos dos Goytacazes, State of Rio de Janeiro, Brazil. Blood smears were done from peripherical blood vessels from 151 calves. Five calves (3.31%) were positive for A. bovis. Symptoms were characterized by debility, fever, pale mucous membranes, and enlargement of prescapular lymph nodes.

Anaplasmosis↗
PubMed1990

[Natural Anaplasma marginale infection in 2 cattle herds with different levels of Boophilus microplus tick infestation].

The dynamics of natural infections by Anaplasma marginale was studied in two adjacent dairy farms with different levels of Boophilus microplus infestation. The farms were located in the enzootic area of bovine anaplasmosis of the Northwest of Argentina. The study was carried out in 35 calves from birth in March-August 1985 to March 1986. The infection rate by A. marginale was evaluated by the observation of blood films and by determination of specific antibodies. The degree of infestation by B. microplus was also evaluated. The tick was found all over the year in farm A with peaks of 100 and 95% of infested calves in October and January, respectively. In farm B, B. microplus was found only in December and January with a maximum of 50% of infested calves. Natural infections by A. marginale started in June until the end of the study when 89% (farm A) and 81% (farm B) of the calves proved to be infected. According to the active serological reactors, the rate rose to a maximum of 85% (farm A) and 81% (farm B) at the end of the study. It is remarkable that 69% of primo-infections by A. marginale in farm B occurred when B. microplus was absent. Moreover, no direct relationship between the peaks of tick infestation and primo-infections with the rickettsie was detected in farm A. The authors concluded that B. microplus could have less importance in the transmission of A. marginale than previously assumed under the local conditions.

Anaplasmosis↗
PubMed1990

Concurrent infection with Theileria buffeli caused depression of parasitaemia in Babesia bovis and Anaplasma centrale infections in splenectomised calves but not in B bigemina infections.

In five experiments undertaken in splenectomised calves it was found that Theileria buffeli infections depressed the parasitaemias of superimposed Babesia bovis and Anaplasma centrale infections, but not B bigemina infections. The course of A centrale infections did not appear to be affected by a concurrent Eperythrozoon teganodes infection.

Anaplasmosis↗
PubMed1987

Attempted transmission to cattle of Anaplasma marginale from overwintered Dermacentor andersoni ticks.

Since the 1983 summer outbreak of anaplasmosis in southern Saskatchewan, the role of the tick, Dermacentor andersoni as an overwintering reservoir for Anaplasma marginale has been questioned. The purpose of this study was to determine if spring-collected ticks carried virulent A. marginale. Sixteen splenectomized calves were assigned randomly to two groups of 14 principals and two controls. Adult D. andersoni, collected in April from areas having high transmission rates of A. marginale, were confined to the ears of the principals by special bags and allowed to feed for eight days. The two control calves were subsequently challenged intravenously with blood from a calf infected with the Virginia strain of A. marginale. Principals and controls were monitored for 60 and 50 days postexposure respectively for signs of infection by clinical, hematological and serological procedures. None of the principals developed anaplasmosis but both control calves developed signs of disease.

Anaplasmosis↗
PubMed1986

Test of the sheep ked Melophagus ovinus (L) as a vector of Anaplasma ovis Lestoquard.

The sheep ked Melophagus ovinus was evaluated as a possible vector of Anaplasma ovis. In 4 tests, 45 to 293 keds were transferred from sheep with acute anaplasmosis, low level parasitemia, or carrier state of anaplasmosis to individual splenectomized ewes. Keds were confined in stockinette cages attached to the dorsal midline of the recipient hosts for 10 days. Throughout the 90-day observation periods after the keds were transferred, no clinical, serologic, or hematologic evidence of anaplasmosis was detected in any of the ked-recipient ewes. Results indicate that sheep keds probably are not mechanical or biological vectors of the ovine anaplasmosis organism.

Anaplasmosis↗
PubMed1987

Bovine anaplasmosis: susceptibility of seronegative cows from an infected herd to experimental infection with Anaplasma marginale.

Adult cows from an Anaplasma marginale-infected herd that were negative to the A marginale rapid card agglutination (RCA) and complement fixation (CF) tests for 1 to 4 years developed acute anaplasmosis after inoculation with 0.5 ml of blood from an A marginale carrier cow. The test cattle were as susceptible as the control cattle of similar ages. Also, 2 cows that had seroconverted from RCA/CF-positive to RCA/CF-negative status naturally were fully susceptible to anaplasmosis when they were experimentally infected. Results of the study indicated that indigenous seronegative cattle in anaplasmosis-enzootic regions probably do not have acquired or natural immunity to A marginale infection.

Agglutination Tests↗