Secretory antibody responses in axenic mice to perorally administered Staphylococcus aureus

Topical oral immunization of axenic mice with non-replicating Staphylococcus aureus resulted in the production of both serum and salivary agglutinins. A latent period of approximately 5 days was noted before salivary antibodies were detected against both a carbohydrate (ChoA) and a protein (PrA) antigen isolated from this micro-organism. The local response to ChoA exhibited a linear increase until day 9 when the reciprocal titres reached a plateau [32 (16--64)]. Salivary antibodies to PrA peaked by day 13 at a mean reciprocal titre of 60 (32--128). The agglutinin response in saliva was found to be initially IgG; however, by day 9 of a 14-day-immunization regimen, IgA became the predominant class of exocrine anti-S. aureus antibodies. The serum agglutinin response followed that found in saliva by approximately 2--4 days. By day 14, all sera (6/6) contained PrA agglutinins, while 4/6 sera agglutinated sheep erythrocytes coated with ChoA. Serum antibodies to ChoA were exclusively IgM, in contrast to IgM and IgA agglutinins elicited by PrA. Absorption studies provided evidence of a specific local and systemic immune response to both ChoA and PrA antigens of perorally administered S. aureus.