Studies on the Biophysical Characteristics of Antibodies Produced in Birds and Mammals in Response to Experimental Chlamydial Infection (Psittacosis)

Circulating complement-fixing and agglutinating antibodies—produced in turkeys, pigeons, sheep, rabbits and a calf at early and late stages of experimental infection with agents of the genus Chlamydia (psittacosis group)—were analyzed by sucrose gradient centrifugation and electrophoretic methods. All species, except pigeons, produced antibodies of the fast sedimenting type early in the course of experimental infection and slow sedimenting type in the later stages. Only slow sedimenting antibodies were found in pigeons. Both molecular types were readily detectable in turkey serums using the indirect complement fixation (ICF) method and in the other species using the direct complement fixation method. Agglutinating antibodies detected by the capillary tube method of Mason were principally of the fast sedimenting type. Electrophoretic patterns of whole serums and gradient separated fractions confirmed that the antibodies were of the γ-globulin type. Inactivating serums at 56°C or 65°C caused a marked shift in the electrophoretic mobility of serum albumin, and 65°C inactivation reduced the γ2-globulin content. The serologic activity of fast sedimenting antibodies produced in the calf was eliminated by 65°C heating (as was previously shown by others). However, heating the serums or gradient fractions thereof from turkeys or sheep not only inactivated the fast sedimenting antibodies but also reduced the titers of slow sedimenting antibodies.