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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.

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PubMed1997

Use of a nonradioactive DNA probe for detection of Anaplasma marginale infection in field cattle: comparison with complement fixation serology and microscopic examination.

A sensitive Anaplasma marginale-specific 409-base pair DNA probe was developed in a previous study for detection of A. marginale infection in experimentally infected cattle with a test that employed slot-blot and in situ hybridization. To test the suitability of the probe to detect A. marginale in the blood of naturally infected carrier cattle, slot-blot hybridization was used to determine the infection rate of A. marginale in cattle from 3 geographic areas in Oklahoma. For comparison, blood samples from the same cattle were also examined by light microscopy and were tested by the complement fixation test. For the DNA hybridization assay, the probe was labeled with digoxigenin 11-dUTP by polymerase chain reaction (PCR). DNA was extracted from blood using the QIAamp blood kit and then applied to a nylon membrane and hybridized with the probe. The study herds consisted of 31 beef cows in Harper County, OK, and 42 and 70 dairy cows from Payne and Pittsburg counties, OK, respectively. In the 3 herds, 80.6%, 92.8%, and 57.1% of the cows were positive for A. marginale as assessed with the DNA hybridization assay. In contrast, only 25.8% and 2.86% were complement fixation positive in 2 herds, and no complement fixation positives were found in 1 herd. Uncountable parasitemia that was too low to accurately determine (< 0.01%) from 29.0%, 4.8%, and 11.4% of the samples, respectively, was demonstrated by microscopic examination. All samples positive by complement fixation and microscopic examination had positive probe reactions in the DNA hybridization assay. Therefore, the PCR-mediated nonradioactive DNA probe described here may be useful in epidemiologic investigations and in identification of carrier cattle. This assay could be adapted for use in diagnostic laboratories because it is sensitive, specific, nontoxic, quickly executed, and inexpensive.

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PubMed1991

Identification of Anaplasma marginale long-term carrier cattle by detection of serum antibody to isolated MSP-3.

Rapid and accurate detection of Anaplasma marginale-infected cattle would enhance anaplasmosis control procedures and evaluation of vaccines. Current tests based on detection of antibodies in serum are not widely used for several reasons, including the occurrence of either false-positive or false-negative results. We evaluated binding of antibodies in serum to a subunit antigen isolated from A. marginale initial bodies--major surface protein 3 (MSP-3). MSP-3 was detected in lysates of eight geographically different isolates of A. marginale and purified by affinity chromatography with monoclonal antibody AmG75C2. Antibodies from cattle infected with any of five geographically different isolates of A. marginale reacted in immunoblots with MSP-3. Sera from uninfected cattle and cattle infected with another rickettsial organism and two hemoprotozoal organisms failed to react with MSP-3. Six carrier cattle infected with the Florida isolate of A. marginale had antibody titers to MSP-3 ranging from 10(3) to 10(6) during a 5-year evaluation period. Since specific antibodies to isolated MSP-3 persist in high titers in long-term carrier cattle sera and MSP-3 is common among A. marginale isolates, it is recommended as a subunit antigen for an anaplasmosis test.

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PubMed1990

Frozen and fresh Anaplasma centrale vaccines in the protection of cattle against Anaplasma marginale infection.

The immunity induced by frozen and fresh Anaplasma centrale vaccines against anaplasmosis caused by A. marginale was tested in 12-month old Friesian steers. A. centrale parasitaemia occurred in all cattle inoculated with both types of vaccine. The average maximal decrease in PCV for the frozen and fresh vaccines was 41.0 and 40.3% respectively. All cattle recovered spontaneously. Vaccinated and control steers of the same age were challenged six months later with doses of 10(6), 10(7) or 10(8) A. marginale organisms. Vaccinated cattle showed average maximal A. marginale parasitemia of 1.2-4.0 versus 10.3-12.0% in control cattle. The average maximal decrease in packed cell volume (PCV) was 33.1 and 30.0% for steers vaccinated with frozen or fresh vaccine, respectively, and 57.4% for the non-vaccinated steers. All vaccinated cattle recovered spontaneously from the A. marginale infection while 7 out of 8 control steers required specific treatment. It thus appears that both frozen and fresh A. centrale vaccines are equally capable of inducing partial protection against infection with A. marginale and of preventing severe red blood cell destruction.

Anaplasma↗
PubMed1991

Analysis of protein compositions and surface protein epitopes of Anaplasma centrale and Anaplasma marginale.

Protein composition was compared and epitopes were analyzed among the isolates of Anaplasma centrale and A. marginale by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblotting using bovine antisera and monoclonal antibodies, and enzyme-linked immunosorbent assay. Common and unique proteins were found among the isolates. All isolates tested had a major surface protein with an apparent molecular weight of 38 to 40 kilodalton which had slight molecular size variations between species. This protein was also a dominant immunogen to the host. At least two species-common epitopes, one of which might contain carbohydrate(s), were present on the major surface protein. One species-specific epitope was identified on the major surface protein of A. marginale isolates.

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