RESPONSE TO TRYPANOSOMA CONGOLENSE INFECTION IN CALVES - DETERMINATION OF IMMUNOGLOBULINS IGG1, IGG2, IGM AND C3 LEVELS AND COMPLEMENT-FIXING ANTIBODY TITERS DURING COURSE OF INFECTION

Abstract

Serum immunoglobulins [Ig], IgG1, IgG2, IgM and C3 [the 3rd complement component] levels and the complement fixing antibody titers were determined over a period of 15-18 wk in 13 calves infected with T. congolense. The mean IgM concentration increased from 2.88 mg/ml prior to infection to 23.75 mg/ml at the 3rd wk after infection. This level dropped by the 5th wk, but elevated values of 13-19 mg/ml were maintained until the end of the experiment. The mean IgG1 level increased from 10.55 mg/ml to a peak of 26.90 mg/ml by 7 wk. After the 10th wk, levels remained in the range of 12-15 mg/ml. There was only a slight increase in mean IgG2 after 7 wk infection, with the highest mean value of 17.09 mg/ml as compared to 10.70 mg/ml of control animals occurring at the 13th wk. The mean C3 concentration decreased from 3.75 mg/ml to 0.95 mg/ml by 2 wk, and fluctuating low levels were maintained for the duration of the infection. The appearance of CF antibody, the decrease in C3 at about 1-2 wk post infection and the subsequent drops in the CF titers and C3 at 5-6, 8 and 11 wk were each coincident with the drops in packed cell volume.