Kinetics of pathogen-specific humoral response in Treponema pallidum-infected young and old inbred strain 2 guinea pigs.

The kinetics of the humoral response to pathogen-specific polypeptides was examined in Treponema pallidum-infected young (3-5 months old) and old (10-20 months old) inbred strain-2 guinea pigs. Sera collected before and at various times after infection were pooled and examined by immunoblotting and two serologic tests (ELISA and FTA) before and after sequential adsorption with CNBr-activated sepharose coupled to normal rabbit proteins and antigens from five nonpathogenic treponemal species. Prior to adsorption the kinetics of the humoral response to T. pallidum antigens did not seem to differ significantly between the two groups. After adsorption, however, a delay in the appearance of detectable antibodies and a milder response to various pathogen-specific polypeptides was observed in the older group. After adsorption, a sharp drop in ELISA-TP, ELISA-TR and FTA titres occurred in both groups. Six months post-infection, between 9 and 10 pathogen-specific polypeptides (97, 57, 47, 45, 43, 39, 37, 33, 17 and 15 kD) were recognized by both groups. The effect of age and levels of natural treponemal antibodies on the clinical symptoms of primary lesions and humoral response to pathogen-specific polypeptides is discussed.