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PubMed1988

Radioimmunoassay for Anaplasma marginale antibodies in cattle.

A radioimmunoassay is described for use in the detection of Anaplasma marginale antibodies in cattle sera. Optimal sensitivity and specificity were obtained by using 2 antigens, an A marginale antigen and a RBC antigen (obtained before infection was established) from the same calf. In addition, sera were preabsorbed with RBC from healthy cattle and with sonicated Babesia bovis. Of 86 sera obtained from cattle with A marginale infection (as determined by blood smear examination or by results of subinoculation of blood from such infected cattle into splenectomized calves), 85 had positive results by use of this test. Of 100 sera obtained from cattle raised in an anaplasmosis-free area, 98 yielded negative results, and sera obtained from 35 cattle (97 sera) infected with B bigemina and from 18 cattle infected with Theileria orientalis yielded negative results. By use of this test, 99 of 100 sera obtained from cattle with B bovis infection were negative for A marginale. Anaplasma marginale antibodies were detected in 18 cattle that had been pastured in a Boophilus microplus-free area for 2 years after natural infection. After 3 years, 16 of these cattle were still seropositive for A marginale. Sixteen cattle pastured in a Bo microplus-infested area had detectable antibody against A marginale 27 months after initial infection with A marginale. Sensitivity and specificity of the test were assessed as 98.8% for each.

Anaplasma↗
PubMed1978

Ultrastructural localization of anaplasmal antigens (Pawhuska isolate) with ferritin-conjugated antibody.

Antibodies from a cow with an experimentally induced infection of the Pawhuska isolate of bovine anaplasmosis were conjugated with ferritin and used to label antigenic sites in preparations of parasitized erythrocytes. Intact erythrocytes did not label on the extracellular surface. Ferritin-conjugated antibody did not pass through the intact erythrocyte to label the parasite, probably due to the large molecular size of the antibody. Damage to erythrocytic plasmalemma and inclusion body in the hemolyzed erythrocytes and complement-fixation antigen allowed labeling of anaplasmal inclusion structures. The positively labeled structures were outer surface of the pellicle, chromatin of the initial body, and inclusion appendage. Unlabeled structures included inner organismic membrane of the initial body, inclusion membrane, fibrillar protoplasmic network of the initial body, and small electron-dense bodies derived from the initial body.

Anaplasma↗
PubMed1986

Percutaneous infection of nymphal Dermacentor andersoni with Anaplasma marginale.

Newly replete nymphal Dermacentor andersoni (principals) were percutaneously exposed to Anaplasma marginale by injection of either intact or lysed infected bovine erythrocytes. Control nymphs were fed on calves with anaplasmosis. The subsequently molted adults were examined for infection by light microscopy, and companion ticks were tested for infectivity by allowing them to feed on susceptible calves. When they fed as adults, both control ticks and percutaneously inoculated principals transmitted A marginale to susceptible calves. Prepatent periods in calves varied according to the method by which nymphs were infected. Colonies of A marginale were found in all ticks that acquired infection by feeding, but colonies were not observed in any ticks exposed percutaneously. The possible developmental cycle of A marginale in artificially infected ticks is discussed.

Anaplasma↗
PubMed1987

Infectivity of three Anaplasma marginale isolates for Dermacentor andersoni.

Three isolates of Anaplasma marginale--Virginia (VAM), Illinois (IAM), and Florida (FAM)--were compared for infectivity for Dermacentor andersoni. The isolates were selected, in part, because of a tail-like appendage that has been demonstrated in the VAM and IAM, but not in the FAM. Ticks were exposed to the isolates as nymphs either naturally by feeding on a calf with anaplasmosis or artificially by percutaneous inoculation with infected bovine erythrocytes. They were examined for infectivity after molting to the adult stage by determining their capability to transmit the disease to susceptible calves and by demonstrating colonies in tick gut sections. Only those ticks exposed to the VAM proved to be infected with A marginale; ticks naturally exposed and those artificially infected with this isolate transmitted the disease to susceptible calves. Colonies of A marginale were observed only in gut tissues of ticks naturally infected with VAM. The IAM (appendage present) and FAM (appendage absent) could not be found in ticks exposed by either method, indicating that factors other than the presence of inclusion appendages may be involved in infection of ticks by A marginale.

Anaplasma↗
PubMed1985

Anaplasma marginale infections in American bison: experimental infection and serologic study.

Anaplasma marginale was experimentally transmitted from cattle to bison and back to cattle. Of the 2 splenectomized and 1 intact American bison calves (Bison bison) inoculated with a North Texas A marginale stabilate, 1 splenectomized and 1 intact bison exhibited clinical signs of anaplasmosis. Active parasitemias in these bison were observed along with positive reactions in the rapid card agglutination and complement fixation tests. Blood from the infected bison produced disease in splenectomized bovine calves. Screening tests for anti-Anaplasma antibodies in 178 blood samples collected from adult bison from the National Bison Range, Montana, revealed 1 rapid card agglutination test-positive sample, and 110 negative, 40 suspect, and 28 positive (15.7%) complement fixation test samples.

Agglutination Tests↗
PubMed1985

Screening for neonatal isohemolytic anemia in calves.

Anti-erythrocytic immunoglobulins in serum and colostrum of 124 anaplasmosis-vaccinated cows were detected with a saline agglutination test. Positive results were correlated with the occurrence of neonatal isohemolytic anemia (NIA) in calves and were used to predict the occurrence of NIA. The disease was prevented by withholding colostrum from calves with a high potential for NIA.

Agglutination Tests↗
PubMed1984

Serologic and clinical responses of premunized, vaccinated, and previously infected cattle to challenge exposure by two different Anaplasma marginale isolates.

Two Anaplasma marginale isolates, one originating in Florida (FAM) and the other from Virginia (VAM), were compared immunologically by cross-challenge exposure of 14 Anaplasma carrier cattle, 8 previously infected cattle, and 6 splenectomized carrier calves. In addition, 28 cattle vaccinated with a commercially available adjuvant killed vaccine and 22 nonvaccinated cattle were challenge exposed with either FAM or VAM. A detectable clinical response was not produced by either FAM or VAM challenge exposure in carrier and previously infected cattle; however, evidence of A marginale growth as characterized by low percentages of parasitemia and increased serum complement-fixation titers was seen in carrier cattle given a heterologous challenge organism and in previously infected cattle inoculated with either homologous or heterologous organisms. Among splenectomized calves, there was virtually no cross protection to the heterologous challenge exposure, whereas a homologous challenge failed to elicit any detectable response. Vaccinated cattle were resistant to VAM exposure, but the clinical response to FAM exposure was severe with a 47% mortality. Most of these cattle displayed typical acute anaplasmosis that was only marginally less severe than that encountered in nonvaccinated cattle.

Anaplasma↗
PubMed1984

Antigen beads: a novel approach for the delivery of a soluble Anaplasma immunogen.

An important consideration in the development of effective immunization regimens against bovine anaplasmosis is the optimization of vaccine delivery systems. This report describes the formulation of proteinaceous antigen-containing spheres derived from supernatant fluids of Analplasma marginale cultures. The antigen beads were designed for use as potential dispersal agents for a soluble Anaplasma immunogen. Immunospecificity assays demonstrated that A marginale antigen was located on the surfaces of individual antigen beads. Use of Anaplasma antigen beads with a potent adjuvant, such as saponin, was proposed.

Adjuvants, Immunologic↗
PubMed1980

Comparison of gloxazone, an effective but toxic anaplasmacide, with imidocarb dihydrochloride.

Eight calves and 15 steers were artificially infected with Anaplasma marginale. When parasitaemia reached 15 per cent, groups of animals were treated with either gloxazone (356C61), or imidocarb dihydrochloride or left untreated as controls. Both compounds were highly effective in the therapy of anaplasmosis. Toxicological studies showed that gloxazone was unacceptably toxic in lactating cattle and also caused nephrotoxicity in rats. Development work with gloxazone as an anaplasmacide has, therefore, been terminated but imidocarb is available.

Anaplasmosis↗
PubMed1983

Influence of a second Anaplasma exposure on the success of treatment to eliminate Anaplasma carrier infections in cattle.

Treatment of adult Anaplasma carrier cows, with long-acting oxytetracycline at dosage levels generally successful in eliminating infection, was unsuccessful when the treatment was preceded or accompanied by a 2nd exposure to A marginale on days 0, 7, or 14 before treatment. Noninfected calves exposed to A marginale 7 days before a similar treatment developed anaplasmosis and became carriers of infection.

Anaplasma↗
PubMed1983

Effects and use of a modified live Anaplasma marginale vaccine in beef heifers in California.

Eighty-one 11-month-old, nonpregnant, Anaplasma marginale-seronegative beef heifers were allotted to 2 groups for evaluation of a modified live A marginale vaccine (n = 50 for vaccinated group and n = 31 for nonvaccinated group). The vaccine induced a mild form of anaplasmosis, as evidenced by a significant (P less than 0.01) decrease in the packed cell volume (PCV) between days 31 and 46 after vaccination. The lowest PCV was 11%, and 3 heifers had a PCV less than 20%. Slight lethargy was evident in some of the vaccinated heifers between days 30 and 45 after vaccination. All vaccinated heifers became seropositive to A marginale, as measured by the complement fixation test and the card test on days 35 and 42 after vaccination, respectively. All nonvaccinated heifers remained seronegative.

Anaplasma↗
PubMed1982

Morphologic alteration of Anaplasma marginale in calves treated with a dithiosemicarbazone.

Blood and clotted blood samples from 3 calves with anaplasmosis were examined by light and electron microscopies before and after the calves were treated twice with alpha-ethoxyethylglyoxal dithiosemicarbazone (given IV). In the treated calves anaplasma bodies were swollen and irregularly shaped and had rough surfaces when viewed by light microscopy. Posttreatment electron microscopic examinations revealed swelling and vacuolation of initial bodies of anaplasma bodies, and ballooning of the vesicular membrane surrounding the anaplasma body. Other initial bodies were ameboid in shape this was or was not accompanied by rupture of the vesicular membrane of the anaplasma body. Necrotic, ameboid-shaped initial bodies also were seen. Some necrotic initial bodies were surrounded by complete vesicular membrane, and others were close to a broken, curled vesicular membrane.

Anaplasma↗
PubMed1981

Comparative titration of Anaplasma marginale antibodies by card agglutination and complement-fixation tests.

The card agglutination test for anaplasmosis was improved so that bovine serum could be titrated for Anaplasma antibodies. The modified test was validated when its results on 1 set of serum samples were compared with the results furnished by the complement-fixation test on the same set. The samples tested were from cows inoculated with an Anaplasma vaccine or with either 1 of 2 virulent strains of Anaplasma marginale. A correlation coefficient of 0.60 was calculated between the values of the titers furnished by the 2 tests, and regression equations were calculated and used to estimate the serum titer in 1 test from a titer measured in the other. The results indicate that the simple card agglutination test can yield titers comparable with those of the complement-fixation test.

Agglutination Tests↗
PubMed1981

Attempts to transmit Anaplasma marginale with Hippobosca rufipes and Stomoxys calcitrans.

Three attempts to transmit anaplasmosis with field collections of Hippobosca rufipes were unsuccessful, despite the fact that the flies had been fed initially on splenectomized cattle acutely infected with Anaplasma marginale. However, 1 out of the 3 attempts, made concurrently with the others, to transmit this organism with Stomoxys calcitrans was successful. The prepatent period was 27 days.

Anaplasmosis↗
PubMed1993

Development of Anaplasma marginale in salivary glands of male Dermacentor andersoni.

Development of the rickettsia, Anaplasma marginale, in salivary glands of male Dermacentor andersoni exposed as nymphs or adult ticks, was studied indirectly by inoculation of susceptible calves with homogenates and directly by examination, using light microscopy and a DNA probe; some unfed ticks were incubated before tissues were collected. Salivary gland homogenates made from ticks in every treatment group caused anaplasmosis when injected into susceptible calves; prepatent periods decreased as the time that ticks had fed increased. Colonies of A marginale were seen only in salivary glands of ticks exposed as adults and not in those exposed as nymphs; the percentage of salivary gland acini infected in these ticks increased linearly with feeding time. However, the probe detected A marginale DNA in salivary glands of ticks from both groups; the amount of DNA detected increased as feeding time was extended. The amount of A marginale DNA appeared to remain constant in gut tissues, but to increase in salivary glands. Salivary glands of adult-infected male ticks that were incubated, but did not feed a second time, became infected with A marginale, and the pattern of infection of acini varied with incubation temperature. Development of A marginale in salivary glands appears to be coordinated with the tick feeding cycle; highest infection rate was observed in ticks exposed as adults.

Anaplasma↗
PubMed1977

Cell-mediated immune response to virulent and attenuated Anaplasma marginale administered to cattle in live and inactivated forms.

The leukocyte migration-inhibition test (LMIT) and lymphocyte transformation of blood leukocytes from cattle exposed to virulent, attenuated, and inactivated preparations of Anaplasma marginale served as indices of cell-mediated immunity in bovine anaplasmosis. The LMIT response increased markedly in cattle vaccinated with attenuated A marginale or injected with virulent A marginale. Cattle inoculated with inactivated anaplasma developed a transient, low-level LMIT response. The response to antigenic stimulation recorded in the lymphocyte transformation test of leukocytes collected from cattle which were given live anaplasma was less than the response elicited from leukocytes collected from cattle vaccinated with inactivated anaplasma in adjuvant.

Anaplasma↗
PubMed1993

Intrastadial and interstadial transmission of Anaplasma marginale by Boophilus annulatus ticks in cattle.

The 1-host tick Boophilus annulatus was found to transmit anaplasmosis in cattle transstadially. Anaplasma marginale was invariably transmitted when ticks that had been pulled off Anaplasma-infected calves either after 7 days (as fully engorged larvae) or after 14 to 15 days (as fully engorged nymphs) were transferred within 4 days to susceptible calves. Three morphologically different A marginale isolates, 1 round (tailless) and 2 with different types of appendages (tailed) were transmitted by the ticks. These findings might explain the overlap of the geographic distribution of the disease and that of Boophilus spp in some areas of the world.

Anaplasma↗
PubMed1977

Influence of dexamethasone on the recrudescence of Anaplasma marginale in splenectomized calves.

Dexamethasone was administered at the dose rate of 0.2 mg/kg of body weight to 11 splenectomized Anaplasma-carrier calves (groups 1 and 3) on Monday, Wednesday, and Friday for 3 weeks. Observations were made on these calves and on 7 nontreated, comparable calves (group 2) to determine the influence of treatment on carrier infections. Dexamethasone treatment was associated in every instance with an exacerbation of the Anaplasma parasitemia and a decrease in packed red cell volume. The episode of acute anaplasmosis was of short duration, resembling the primary response, except that complement-fixation response did not increase accordingly. Serum protein electrophoresis of serums from 4 calves (group 3) undergoing the drug-induced response failed to show any significant change during the 3-week treatment period, but did show a significant increase in gamma-globulin immediately after treatment.

Anaplasmosis↗