Strain differentiation of Neisseria gonorrhoeae by reverse passive hemagglutination

Abstract

A reverse passive hemagglutination test that utilizes human erythrocytes coated with antibody to gonococci was developed to distinguish differences among 11 strains of Neisseria gonorrhoeae. Different rabbits were immunized with each strain of gonococcus. Antibody was purified by passing antiserum over an immunoadsorbent column containing homologous cell walls trapped in a crosslinked polyacrylamide gel. Antibody, after absorption with N. meningitidis, was used for coating 11 individual suspensions of erythrocytes, each with antibody to one gonococcal strain. The panel of coated erythrocytes was added to microtiter trays containing dilutions of homologous bacterial lysate and lysates from 10 heterologous strains. Agglutination titers were highest with homologous lysates, although cross-reactions occurred among some heterologous lysates. Lysates of nongonococcal Neisseria species and of other genera did not agglutinate coated erythrocytes. The reverse passive hemagglutination test can be a useful procedure to distinguish differences among strains of N. gonorrhoeae. Numerous attempts have been made to distinguish strains of Neisseria gonorrhoeae. Several serological methods have been used, including complement fixation (21), capillary precipitin (14), agar gel diffusion (9), hemagglutination inhibition (1), bactericidal assay (10, 23), and in vivo protection (2). Pili have been used as a means of separating strains (3, 19). In addition, strains have been differentiated by distinct patterns in polyacrylamide gels (15) and by differential sensitivity to pyocins (22). Recently, a micro-immunofluorescence procedure has been used to classify N. gonorrhoeae into three major immunotypes and several subtypes (26). Hirata et al. (12) used a reverse passive hemagglutination (RPHA) procedure to detect hepatitis B surface antigen. Using stabilized erythrocytes coated with antibody to hepatitis B surface antigen, they reported that the assay was easy to perform, reproducible, and sensitive. This report describes an RPHA procedure to study differences among 11 strains of N. gonorrhoeae. MATERUILS AND METHODS Organisms. Eleven isolates of Neisseria gonorrhoeae were used in these studies. Three strains (NG-2, F4, and 2686) were received from D.