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Demonstration of Anaplasma marginale Theiler in Dermacentor variabilis (Say) by ferritin-conjugated antibody technique.

Cattle were inoculated with a Virginia isolate of Anaplasma marginale Theiler and served as an infective source for laboratory-reared Dermacentor variabilis (Say) nymphs. Transstadial transmission of A marginale was demonstrated by feeding the newly molted adult ticks on susceptible cattle and by inoculation of gut homogenates collected from adult ticks at postattachment day 6. A similar gut homogenate from the same group of ticks was caused to react with A marginale-bovine antisera that had been conjugated with ferritin. The homogenate contained organisms similar to those observed in the gut of adult feeding ticks that were infected as nymphs and the labeling of the outer membrane confirmed that organisms observed were A marginale. A gut homogenate prepared from control ticks did not cause infection when inoculated into a susceptible cow and no organisms were demonstrated.

Anaplasma↗

Isolation of Anaplasma marginale from Rhipicephalus simus males.

Approximately 100 adult Rhipicephalus simus from a batch known to be infected with Anaplasma marginale were used to infest an ox. Fifty male ticks were manually removed from the animal's ears 9 days after infestation. These ticks were triturated and a stabilate was prepared which was injected intravenously into 2 susceptible oxen. Both these animals became infected with A. marginale. The prepatent periods following inoculation of the tick suspensions before and after freezing in liquid nitrogen were 16 and 17 days respectively.

Anaplasma↗

Liquid nitrogen storage of Anaplasma marginale complement-fixation antigen by a multiple small aliquot technique.

Anaplasma marginale complement fixation test antigens were frozen as drops in liquid nitrogen using an easily constructed apparatus. Economy in the use of antigen was achieved as the frozen drops were retrieved from storage in any required volume. The potency of the antigen was unaffected by the freezing and thawing technique. The technique is useful for storing other biological reagents.

Anaplasma↗

Cross reactivity between Anaplasma marginale and two Plasmodium species as demonstrated by passive hemagglutination.

Two types of antigens were prepared from each of 3 partially purified preparations of Anaplasma marginale, Plasmodium lophurae, and P berghei. Hemagglutination tests were conducted with homologous serums to detect antigenic relationships between these organisms. Serums were also absorbed with both homologous and heterologous antigen preparations. Cross reactivity between these organisms was observed.

Anaplasma↗

Effect of 2-mercaptoethanol on the in vitro response of sensitized bovine peripheral blood lymphocytes to Anaplasma antigen.

Sensitized lymphocytes from 3 cows vaccinated with anaplasma antigen were isolated and caused to react in vitro with antigen in a microculture lymphocyte transformation test. The addition of 2-mercaptoethanol at a concentration of 25 mul of 4 X 10(-3) M solution/well significantly (P less than or equal to 0.01) increased [3H]thymidine incorporation compared to microculture without 2-mercaptoethanol.

Anaplasma↗

Effect of 4-bromo-calcium ionophore A23187 on release of Anaplasma marginale from bovine erythrocytes in vitro.

The ionophore A23187 was used to facilitate release and continued development of Anaplasma marginale in short-term erythrocyte cultures. Addition of 10 microM A23187 to the cultures resulted in significant decrease in percentage of parasitized erythrocytes (PPE) by 24 hours after treatment; further development and increase in PPE was not observed. In contrast, the PPE of untreated cultures, those treated with dimethyl sulfoxide (DMSO) only and with 1 microM A23187 increased slightly during that time. Total erythrocyte count decreased in treated cultures in excess of that expected after samples of the medium were taken for analysis. The greatest cell loss and increased hemoglobin concentration in culture medium was observed in cultures treated with 10 microM A23187 and with an equivalent volume of DMSO. The DMSO appeared to cause hemolysis of some erythrocytes, but not of infected cells selectively. Release of A marginale inclusion bodies was seen by electron microscopy in samples from the 10 microM A23187-exposed cultures. At 30 minutes after treatment, free initial bodies were frequently seen. Inclusion body membranes and individual A marginale were associated with membranes of adjacent erythrocytes. Individual rickettsiae were seen in cell depressions and appeared to be entering erythrocytes. However, neither further invasion nor development of the parasite in erythrocytes was observed. Ionophore A23187 appeared to promote release of A marginale from erythrocytes, but did not enhance infection of erythrocytes or development of organisms in vitro.

Anaplasma↗

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↗

Field observations on the duration of immunity in cattle after vaccination against Anaplasma and Babesia species.

In an outbreak of Babesia bovis in a large herd of Friesian x Malawi Zebu cattle, which occurred after an interruption of intensive dipping, clinical or fatal babesiosis occurred in 54/299 (18.1%) animals which had never been vaccinated, as compared to 9/153 (5.9%) vaccinated animals. Eight of the nine affected vaccinates had been vaccinated more than 27 months previously. Sera were collected every 3-4 months from 33 Friesian x Malawi Zebu heifers maintained with intensive dipping and vaccinated with trivalent B. bovis, Babesia bigemina and Anaplasma centrale vaccine. After 2 years, 25% had become seronegative for B. bovis by indirect immunofluorescence, as compared to 97% for B. bigemina and 46% for A. centrale. Because of the evidence that immunity following vaccination against B. bovis declines after 2 years in the absence of tick challenge, it is recommended that tick control should be relaxed after immunity has been established, in order to save acaricide, reinforce immunity and avoid any need for revaccination.

Anaplasma↗

Anaplasma marginale: detection of carrier cattle by PCR-ELISA.

A highly sensitive and specific polymerase chain reaction (PCR) based assay for the detection of the minute levels of Anaplasma marginale present in the blood of long-term carrier cattle was developed. A simple lysis method was used to remove most of the haemoglobin from the blood to facilitate direct input of samples into the PCR reactions without prior purification of the DNA. PCR product was detected by enzyme-linked immunosorbent assay (ELISA) to simplify the processing of large numbers of samples. The sensitivity limit of the PCR-ELISA was 0.00015% parasitaemia (24 infected erythrocytes per microlitre of blood). No cross-reactivity of the assay was observed when A. marginale-negative blood infected with Babesia bovis or Theileria orientalis was tested. The PCR-ELISA was shown to be 92% efficient in the detection of long-term A. marginale carrier cattle. No false-positive results were obtained. These results compared favourably with 2 serological assays for detection of A. marginale carrier cattle (card agglutination test and ELISA) which were applied to the same experimental animals.

Agglutination Tests↗

Effects of temperature and time on the infectivity of Cryogenically preserved samples of Anaplasma marginale- infected erythrocytes.

The effects of temperature (25 C) and time (2, 4, 6, 8, 12, 24, 48, 72, 96 hours and 5, 13, and 19 days) were determined on thawed samples of Anaplasma marginale-infected erythrocytes cryogenically preserved with dimethyl sulfoxide and frozen in liquid nitrogen. Inoculation into splenectomized calves indicated that infectivity was not destroyed by either time or temperature from 2 to 72 hours, but was destroyed at 96 hours. The incubation periods of the disease in inoculated splenectomized calves increased in proportion to the length of time the samples were held at 25C.

Anaplasma↗

Survival of Anaplasma marginale in Aedes albopictus cells.

Bovine red blood cells infected with Anaplasma marginale were introduced into cell line cultures from the mosquito Aedes albopictus. The cultured mosquito cells phagocytized both infected and uninfected red blood cells. The parasite remained viable, as determined by calf inoculations, for 21 days.

Aedes↗

Cutaneous hypersensitivity and isoantibody production in cattle injected with live or inactivated Anaplasma marginale in bovine and ovine erythrocytes.

Delayed cutaneous hypersensitivity and the production of isoagglutinins against normal bovine erythrocytes were measured in cattle inoculated with erythrocytic preparations containing live or inactivated Anaplasma marginale. The effect of blood group substances versus parasitic components on induction of delayed cutaneous hypersensitivity and isoimmunity was examined by using test antigens derived from normal and parasitized erythrocytes, virulent A marginale in bovine erythrocytes, and attenuated A marginale in ovine erythrocytes. The use of inactivated vaccine of bovine origin induced production of isoantibodies and cutaneous hypersensitivity to both bovine and ovine blood group factors, whereas a similar vaccine preparation of ovine origin stimulated antibodies and cutaneous reactivity only against ovine blood group factors.

Anaplasma↗

Effect of chemotherapy on semen characteristics of Balami rams infected with Anaplasma ovis.

Six intact Balami rams were experimentally infected with Anaplasma ovis. Another six were infected one month after splenectomy and six others served as controls. Clinical manifestations of the disease, first observed between 5 to 7 days post-infection, were more severe and prolonged in the splenectomised-infected than in the intact-infected group. There was progressive deterioration in semen quality, which was also significantly more severe and prolonged in the splenectomised than in the intact-infected rams. Following treatment with long-acting terramycine, clinical recovery occurred earlier in the intact-infected (1-4 weeks) than in the splenectomised-infected group (5-7 weeks). A similar pattern was observed in post-treatment improvement in the sperimiogram. However, although the infected animals recovered clinically by 1-7 weeks post-treatment, restoration of the reproductive potential did not occur for 20 to 25 weeks. It appears that stress factors may aggravate the deliterious effects of anaplasmosis.

Anaplasmosis↗

Survival of Aegyptianella pullorum, Anaplasma marginale and various parasitic protozoa following prolonged storage in liquid nitrogen.

Various protozoa species were examined using in vivo and in vitro methods to determine their ability to survive prolonged periods of storage in liquid nitrogen. The following protozoan species were successfully recovered after they had been cryopreserved for a period over 10 years: Trypanosoma lewisi, T. cruzi, T. congolense, T. brucei, T. rhodesiense, T. gambiense, T. evansi, T. equinum, T. equiperdum, Leishmania donovani, Plasmodium berghei, P. praecox (relictum), Babesia rodhaini and B. canis. The longest survival period that has been successfully tested so far is between 5 and 7 years for Eimeria species, for monoxenically (A--C) and axenically grown E. histolytica cultures between 2 and 7 years and trichomonades, including Crithidia sp., between 6 and 8 years. Aegyptianella pullorum was successfully recovered after 6.97 years and Anaplasma marginale after 1.92 years. The freezing techniques are briefly described.

Animals↗

The effect of natural exposure to Anaplasma and Babesia infections on native calves in an endemic area of Colombia.

The age at which native calves first became infected with Anaplasma marginale and Babesia bigemina and the effect of the infections as characterised by anaemia was determined by the biweekly examination of newly born calves on four ranches located in an endemic area of anaplasmosis and babesiosis on the north coast of Colombia. All of the calves examined became infected with A. marginale at 4-24 weeks of age and with B. bigemina at 2-34 weeks of age. The mean age at first infection with both haemoparasites was 11 weeks. A significant decrease occurred in the mean packed cell volumes of the calves following infection. However, the packed cell volumes returned to preinfection levels with 4 weeks following infection and most calves recovered from their first natural infections without apparent serious consequences. The mild clinical response and rapid recovery indicated that the protection of native calves through immunisation or other procedures prior to natural exposure would be of questionable value.

Age Factors↗

Anaplasma marginale, Eperythrozoon wenyoni: lectin reactions with bovine erythrocytes.

Normal bovine erythrocytes were agglutinated with four of five lectins specific for different oligosaccharides. The order of reactivity was wheat germ greater than ricin greater than soybean greater than peanut. Concanavalin A did not agglutinate normal bovine erythrocytes. After neuraminidase treatment of normal bovine erythrocytes, each lectin agglutinated the cells with decreased concentrations of lectin, verifying that partial removal of sialic acid exposes more of each lectin's binding sites or alters the binding site such that fewer molecules of lectin are required to initiate agglutination. A change in agglutination of erythrocytes using soybean agglutinin and peanut agglutinin occurred when cells were obtained from cattle infected with Eperythrozoon wenyoni. The results suggested that an alteration in erythrocyte membranes occurred as a result of this infection as manifested by the increased recognition of both the soybean agglutinin and peanut agglutinin receptor carbohydrates. A similar effect was indicated with erythrocytes obtained during an acute Anaplasma marginale infection; however, an ensuing reticulocytosis masked the effect, requiring the use of fluoresceinated lectins to verify that increased binding of each lectin occurred with infected cells when compared to normal cells.

Anaplasmataceae Infections↗