Protein G ELISA for detection of antibodies against Toxoplasma SAG1 in dromedaries.

ELISA was used for detection of antibodies against the immunodominant surface antigen 1 (SAG1, synonymous P30) of Toxoplasma gondii, and peroxidase-conjugated protein G was used instead of commercially unavailable enzyme-conjugated anti-dromedary antibody. A latex agglutination test was employed to select 20 seronegative control animals, and peroxidase-conjugated protein A was used for comparison with protein G. The overall seroprevalence rate was 31.4%; males had to some extent higher seropositive rate than females (P = 0.077). Seropositive camels sampled in winter had significantly higher-antibody levels than those sampled in summer (P < 0.01). ELISA values using protein G and protein A conjugates were significantly correlated (Spearman's rho = 0.797; n = 185; P < 0.001). The results were discussed.