Identification of antigens of two isolates of Anaplasma marginale, using a western blot technique

Antigens of the Illinois (IAM) and Florida (FAM) isolates of Anaplasma marginale were analyzed, using the western blot technique and antiserum from A marginale-infected calves. Crude antigens were prepared from the parasitemic blood of each. Antiserum was collected after the primary and recrudescent parasitemias. Antigens were separated, using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Antigens were then transferred onto nitrocellulose membranes and exposed to test sera. Antibodies attached to the membrane-bound antigens were detected, using an avidin/biotin peroxidase assay and biotinylated rabbit anti-goat immunoglobulin G. Antigens detected were of a high molecular weight group (108 to 91 kilodaltons [kd]) or of a low molecular weight group (47 to 27 kd). The IAM antigens were 100 kd, 96 kd, 47 kd, 38 to 43 kd, and 27 kd; these antigens were detected, using anti-IAM and anti-FAM antibodies, but the anti-FAM antibodies had a strong reaction to only the 100-kd and 38- to 43-kd antigens of IAM. The FAM antigens were 108 kd, 91 kd, 47 kd, 38 to 43 kd, and 27 kd; these antigens were detected, using anti-FAM antibodies and, except the 91 kd antigen, anti-IAM antibodies. Because the 91-kd antigen was detected only in the FAM antigen and detected only by sera from FAM-infected calves, this isolate-specific antigen may be associated with the ability of FAM to induce disease in an IAM-immune animal. Sheep anti-A ovis antibodies reacted only to the 38- to 43-kd antigens of each isolate, indicating that these antigens may be genus-specific.(ABSTRACT TRUNCATED AT 250 WORDS)