NATURALLY-OCCURRING PIA PIB HYBRIDS OF NEISSERIA-GONORRHOEAE/

The major outer membrane protein of Neisseria gonorrhoeae, For, functi ons as a porin and is thought to occur as one gene with two alleles. T he immunologically distinct epitopes of the two subclasses, IA and IB, have allowed the development of serotyping schemes. Clinical isolates of N. gonorrhoeae are believed to express only a single type of For, either IA or IB. We have encountered two clusters of isolates that rea ct with antibodies to both IA and IB Por. Isolates within the clusters are indistinguishable by the phenotypic characteristics tested. In ad dition, the amplification of the por gene in representative isolates s howed that the por gene of the hybrids gave similar restriction digest patterns within but not between the clusters.