Immunoblotting of a Staphylococcus aureus DNA library as a tool for isolating potential antigenic proteins

A Staphylococcus aureus DNA library was created in the lambda vector EMBL4 and expressed in Escherichia coli strain Y1090. Plaques were screened using serum from a S. aureus-infected patient. A number of positive clones that expressed proteins recognised by serum antibodies were further analysed using Western blots of total lysates from cultures infected with the lambda clones. Differences were found between patient and control sera in both the specificity and titre of anti-S. aureus antibodies. Expressed staphylococcal proteins appeared to be stable and were easily distinguishable from E. coli proteins in the Western blot. This method may have applications in specifically selecting clones encoding antigens associated with infection and may be of potential use clinically.