title: Effects and use of a modified live Anaplasma marginale vaccine in beef heifers in California.
abstract: 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.
mesh_terms: D000709:Anaplasma / Q000276:immunology*; D000712:Anaplasmosis / Q000276:immunology / Q000517:prevention & control*; D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology; D001835:Body Weight / Q000187:drug effects; D002140:California; D002353:Carrier State / Q000209:etiology / Q000662:veterinary*; D002417:Cattle; D002418:Cattle Diseases / Q000209:etiology / Q000276:immunology / Q000517:prevention & control*; D005260:Female; D006400:Hematocrit / Q000662:veterinary; D014611:Vaccination / Q000662:veterinary*; D014613:Vaccines, Attenuated / Q000276:immunology
chemical_list: D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated