ANTIGENIC RELATIONSHIPS AMONG IMMUNOGLOBULIN A1 PROTEASES FROM HAEMOPHILUS, NEISSERIA, AND STREPTOCOCCUS SPECIES

To investigate the antigenic variation and relationships of immunoglob ulin Al (IgA1) proteases among different species and genera, we examin ed a comprehensive collection of serine type and metallo-type IgA1 pro teases and corresponding antisera in enzyme neutralization assays. Sha ring of neutralizing epitopes of metallo-type IgA1 proteases from Stre ptococcus pneumoniae, Streptococcus sanguis, Streptococcus mitis, and Streptococcus oralis and of serine type IgA1 proteases from Haemophilu s and pathogenic Neisseria species was extremely limited. A number of limited to strong cross-reactions in such epitopes were found among se rine type IgA1 proteases released by members of the genera Haemophilus and Neisseria, reflecting the common origin of their iga gene. Howeve r, the relatively limited prevalence of shared ''neutralizing'' epitop es of IgA1 proteases from the two genera indicates that they rarely in duce immunity to each other. In contrast, extensive sharing of neutral izing epitopes was found between N. meningitidis and N. gonorrhoeae Ig A1 proteases, making them potentially attractive vaccine components. A mong metallo-type IgA1 proteases, several pneumococcal proteases were found to induce neutralizing antibodies to IgA1 proteases of oral stre ptococci whereas the opposite was not the case.