Thermostable Neisseria gonorrhoeae antigens examined by a bacterial agglutination test.

Rabbit antisera against three different N. gonorrhoeae isolates agglutinated heated gonococci (100 degrees C, 2 h) before and after treatment with periodate or pronase, but this was not the case with gonococci exposed to the combined action of the reagents. All agglutinins could be removed by absorption of antiserum with untreated or heat-treated gonococci or with a heat extract of the bacteria. Antiserum absorbed with the lipopolysaccharide still agglutinated the heated gonococci both before and after exposure of the bacteria to periodate or pronase. The results of cross-absorption experiments indicated strain variation of thermostable antigenic determinants involved in the agglutination reaction.