Mucosal and systemic humoral immune response to Bordetella avium in experimentally infected turkeys.

Antibody response to Bordetella avium was measured in serum and mucosal secretions of experimentally infected turkeys. Two-day-old turkeys were inoculated with B. avium, and four inoculated turkeys and four uninoculated control birds per trial were euthanatized weekly from 1 through 8 weeks postinoculation (PI). Maternal antibody of the IgG isotype, present in all 2-day-old birds sampled, decreased to background levels by 3 weeks of age. Antibody (IgG, IgM, IgA) was detected in serum, tracheal washings, and lacrimal secretions in response to B. avium infection. Regardless of the sample site and isotype, antibody levels peaked at 4-6 weeks PI and then decreased rapidly from 6 to 8 weeks PI. In general, IgM and IgA levels peaked earlier (4-5 weeks PI) but declined more rapidly than IgG levels. Numbers of B. avium in the trachea peaked at 2-3 weeks PI and then decreased rapidly from 4 to 8 weeks PI. Even though no direct causal relationship could be determined, the results indicate that an increasing level of antibody in serum, tracheal washings, and lacrimal secretions is temporally associated with clearance of B. avium from the trachea.