Human antibody response to the major adhesin of Mycoplasma pneumoniae: increase in titers against synthetic peptides in patients with pneumonia.

Peptides corresponding to parts of the P1 protein (major adhesin) of Mycoplasma pneumoniae were synthesized. On the basis of predicted antigenicity, seven sequences containing 17 to 21 amino acids were selected. In addition, one peptide containing a sequence of 13 amino acids shown to be related to cytadherence of M. pneumoniae was included. Serum samples from 56 patients with pneumonia were tested for a rise in titers of specific IgG during infection, using the peptides as coating antigens in ELISA. A titer rise against one or more peptides was observed in 10 out of 13 patients with serological evidence of mycoplasmal etiology. Specific antibodies to two or more peptides were demonstrated in three patients, whereas seven patients responded to one peptide only. In the sera from patients with pneumonia of non-mycoplasmal etiology, no titer rises above the cut-off level were observed. Our results indicate that a combination of four peptides would be possible for use as antigen for serological diagnosis of infections with M. pneumoniae.