Randomly amplified polymorphic DNA genotyping of serogroup A meningococci yields results similar to those obtained by multilocus enzyme electrophoresis and reveals new genotypes

Abstract

Randomly amplified polymorphic DNA (RAPD) genotyping was applied to one representative strain of each of the 84 electrophoretic types (ETs) of Neisseria meningitidis serogroup A previously defined by multilocus enzyme electrophoresis (MEE) (J.-F. Wang et al., Infect. Immun. 60:5267-5282, 1992). Twenty-seven additional isolates comprising six ETs were also tested. MEE and RAPD genotyping yielded similar dendrograms at the subgroup level. Similar results were obtained by both methods for 18 serogroup A meningococci isolated in The Netherlands between 1989 and 1993. Ten of these isolates defined a new subgroup, designated subgroup IX. One isolate belonged to the ET-5 complex, normally associated with serogroup B strains (D. A. Caugant et al., Proc. Natl. Acad. Sci. USA 83:4927-4931, 1986). By RAPD genotyping, meningococci can be linked to previously characterized genotypes by using a computerized database, and dendrograms based on cluster analyses can easily be generated. RAPD analysis offers advantages over MEE since intermediate numbers of isolates of serogroup A meningococci can quickly be assigned to known subgroups and new subgroups can be defined.

FIG. 1

Representative RAPD patterns obtained with primer 1254 for representative serogroup A isolates. Lanes: M, marker; 1, ET-11 strain; 2, ET-38 strain; 3, ET-33 strain; 4, ET-39 strain; 5, ET-44 strain; 6, ET-28 strain; 7, ET-41 strain; 8, ET-55 strain; 9, ET-48 strain; 10, ET-75 strain; 11, ET-78 strain; 12, ET-79 strain; 13, ET-83 strain; 14, ET-70 strain; 15, ET-72 strain.

FIG. 2

Comparison of the genetic relationships inferred by RAPD analysis (left) and MEE (right) (data for MEE are adapted from reference 14). The dendrograms resulting from cluster analysis show the genetic distance at which the clusters divided according to the unweighted pair group average clustering algorithm. In the dendrogram obtained by MEE, subgroups are indicated by Roman numerals and individual ETs are numbered 1 to 84 (top to bottom). Subgroups containing the same ETs in the dendrograms obtained by MEE and RAPD analysis are indicated by colored bars. Subgroup II is split into ET-39 and ET-40 isolates versus ET-41 isolates, as indicated by the numbers at the end of the branches. ET-28 isolate B534 is indicated by its strain number. Other ET-28 strains are labelled 28 at the ends of the branches. The recent Dutch isolates that have been tested are marked with dots: purple dots, ET-33 (strains 892411 and 902488); orange dots, ET-48 (strains 900973, 920054, and 921710) and strain 891780; green dot, new genotype within the serogroup A strains (strain 921051); blue dots, subtype P1.16 strains (strains 890461, 890592, 890867, 901335, 911652, 911960, 920521, 921268, 931114, and 931192); red dot, serotype 15 strain (strain 892665) related to the serogroup B ET-5 complex (see text).