Genetically modified live vaccine offers protective immunity against wild-type Anaplasma marginale tick-transmission challenge.

Anaplasma marginale is a tick-borne pathogen of cattle that causes bovine anaplasmosis in tropical and subtropical regions throughout the world. Killed vaccines derived from infected erythrocytes have been used for control of this disease with limited success. Recently, we described a targeted deletion mutation in the phage head-to-tail connector protein gene of A.