Clonal and variable properties of neisseria meningitidis isolated from cases and carriers during and after an epidemic in the gambia, west africa

A representative collectionof meningococci wasisolated from casesand healthy carriers in The Gambia between 1982 and 1988, during and after an epidemicof meningococcal meningitis. These bacteria were subjected to a clonal analysis. All serogroupA bacteria from both cases and carriers wereof one clone (A IV-I). Several unrelated clones were observedamong serogroup29E and serogroupYcarrier strains. The serogroupA strains wereuniform for serotypeand subtype antigens (serotype4, subtype Pl.7) and antibiotic sensitivitypattern. Occasionalstrains variedin their lipopolysaccharide(LPS), DNAfingerprint pattern, and/or the quantitative expression of the class 1 protein. A high degree of strain-specific variation wasfound for the expression of class5 proteins, pili, and sulfonamide sensitivity. The frequency of strains expressing reduced amounts of the class 1protein, alteredLPS, and/or increasedamounts of capsular polysaccharideroseamong case strains obtained after the epidemic had ceased. These strains seem to be generally resistant to antibody-mediated bactericidal activity. © 1989 by The University of Chicago. All Rights Reserved.