Unusual antineisserial activity expressed by a systemic isolate of Neisseria meningitidis. Antimeningococcal effect and properties

Antineisserial activity expressed by the systemic Neisseria meningitidis st rain 77/79A was studied using the cross-streaking technique. Of 271 meningo coccal isolates tested, > 84% were sensitive to this strain. The degree of susceptibility was largely dependent upon the agent characteristics of the individual isolates. Serogroup A sulfonamide-resistant systemic strains and non-groupable sulfonamide-sensitive isolates from healthy carriers were hi ghly sensitive to the antagonistic activity. Among insensitive or weakly se nsitive strains, serogroup B sulfonamide-resistant isolates dominated. The activity is of general interest as it also antagonized growth of bacterioci n producers. Colonization by the producer strain might determine the agent characteristics of a surviving population. Group B was predominant among di sease-causing strains in Norway at the time when strain 77/79A was isolated . A component was purified by ammonium sulfate precipitation, gel filtratio n and hydrophobic interaction chromatography. It was bacteriostatic and par tly resistant to proteolysis by trypsin. Preparations remained active after 30 min at 90 degreesC, but activity was lost after 20 min at 120 degreesC. Nevertheless, sodium dodecyl sulfate-polyacrylamide gel electrophoresis pr oduced a band by Coomassie Brilliant Blue staining, corresponding to a mole cular mass of approximate to 52 kDa. Further characterization was limited d ue to the low levels of active substance produced.