title: The influence of maternal antibody and age of calves on effective vaccination against Leptospira interrogans serovar hardjo.
abstract: Twelve seronegative cows were vaccinated with an experimental bivalent Leptospira interrogans serovars hardjo and pomona vaccine late in their first pregnancy. Calves born of these dams were divided into 4 equal groups that received this vaccine at 4, 6, 10 and 18 weeks of age, respectively. Before vaccination the group geometric mean titres of maternally-derived circulating antibodies ranged from 2 to 25 for the microscopic agglutination (MA) test and 3 to 35 for enzyme-linked immunosorbent assay (ELISA) using a serovar hardjo outer envelope antigen. Post-vaccination peak titres were 645 to 1612 for MA and 562 to 1037 for ELISA, respectively. Calves vaccinated at the youngest age, had the highest pre-vaccination circulating maternal antibody titres, but showed the smallest rise in post-vaccination antibody titres. Circulating maternal antibody was detected in calves up to 13 weeks of age. All immunised calves were protected against a virulent challenge with serovar hardjo type Hardjobovis, regardless of their age or maternally-derived antibody titres. These findings indicate that calves as young as 4 weeks old, vaccinated in the presence of maternally-derived antibody, can be fully protected against homologous virulent challenge.
authors.affiliation: Commonwealth Serum Laboratories, Parkville, Victoria.
authors.forename: A
authors.initials: A
authors.lastname: Palit
authors.forename: H
authors.initials: H
authors.lastname: Middleton
authors.forename: J
authors.initials: J
authors.lastname: Sheers
authors.forename: C
authors.initials: C
authors.lastname: Basilone
mesh_terms: D000367:Age Factors; D000372:Agglutination Tests / Q000662:veterinary; D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology*; D005260:Female; D007112:Immunity, Maternally-Acquired / Q000276:immunology*; D007921:Leptospira interrogans / Q000276:immunology* / Q000472:pathogenicity; D007922:Leptospirosis / Q000276:immunology / Q000662:veterinary*; D011247:Pregnancy; D014611:Vaccination / Q000662:veterinary*; D014774:Virulence
chemical_list: D001428:Bacterial Vaccines