Neisseria gonorrhoeae acquire a new principal outer-membrane protein when transformed to resistance to serum bactericidal activity.

Resistance to the complement-dependent bactericidal activity of normal human serum is found in nearly all Neisseria gonorrhoeae strains causing disseminated gonococcal infection. Transformation of serum-sensitive gonococcal strain NRL 7189 to serum resistance using deoxyribonucleic acid from three separate disseminated-infection gonococci was accompanied by simultaneous structural and antigenic changes in the principal outer-membrane protein (POMP) of the transformants. In each of 10 separate transformations, there was a reduction in subunit molecular weight of the POMP from that in the recipient (39,000) to that in the deoxyribonucleic acid donors (36,500). Also, in each instance the POMP antigenic type, as measured by enzyme-linked immunosorbent assay, converted from that of the recipient to an antigenic type common to each DGI donor strain. This conversion of POMP antigen was reflected in part by changes in the surface fluorescence of the transformed gonococci to the microimmunofluorescence pattern of the donor strains. These results suggested that serum resistance of gonococci is related to the possession of a POMP of characteristic subunit molecular weight and antigenicity.