Antibodies to iron-regulated proteins of meningococci in blood sera of healthy persons of different age groups

One hundred and twenty individual sera obtained from healthy persons of different age groups were studied for the presence of antibodies to meningococcal iron-regulated proteins (IRP). The study revealed that occurrence of such antibodies in sera under study was IRP nature- and age-dependent. Antibodies to two IRP were found to occur most frequently: 85 kD (TbpB) and 72 kD (FrpB). Antibodies to the former IRP were detected in more than 50% and antibodies to the latter IRP, in more than 90% of sera. This was probably due to the presence of epitopes common with those in protein antigens of some other microorganisms, such as Moraxella catarrhalis and Haemophilus influenzae. The occurrence of antibodies to periplasmatic IRP with 34 kD (FbpA) in blood sera varied within the range of 5 to 30%. At the same time the occurrence of antibodies to this protein in the sera under study was age-depended: children until five years exhibited the minimal occurrence (about 5%), while in adults it reached 30%.