IgG avidity ranges for Brucella abortus obtained in iELISA using anti-bovine IgG or protein A labeled with peroxidase (HRPO) in two groups of bovine serum samples

Avidity rangeaNo. of serum samples (%)b
Anti-bovine IgG-HRPOProtein A-HRPO
    Low avidity (AI <50%)4 (10)10 (25)
    High avidity (AI >50%)36 (90)30 (75)
    Low avidity (AI <50%)1 (6.3)7 (77.8)*
    High avidity (AI >50%)15 (93.7)*2 (22.2)
  • a GI, nonvaccinated seropositive cows originated from areas where Brucella is endemic or an outbreak is occurring (n = 40); GII, S19-vaccinated heifers between 3 and 8 months of age, originated from areas where Brucella is endemic, and serum samples were analyzed at 3 months postvaccination (n = 79).

  • b *, significant differences between anti-bovine IgG-HRPO and protein A-HRPO as determined by the χ2 test with Yates correction (P < 0.05).