Finite purification of Anaplasma marginale: serologic inactivity of the anaplasma body.

Anaplasma bodies finitely purified by affinity chromatography to eliminate all traces of erythrocytic stromata were not agglutinated by serum from calves having acute anaplasmosis. The stromata which were associated with the anaplasma bodies were also finitely purified and agglutinated with such serum. The evidence indicates that the antibody in anaplasmosis that is detected by agglutination tests is directed against the erythrocytic stromata and not against the finitely purified anaplasma bodies.