Cleavase fragment length polymorphism analysis of Neisseria meningitidis basic metabolic genes

Cleavase fragment length polymorphism (CFLP) is a subtyping system based on the property of the enzyme cleavase to recognize junctions between single- and double-stranded regions of DNA formed after denaturation and cooling. To assess the capacity of CFLP for discriminating Neisseria meningitidis serogroup B strains belonging to the electrophoretic type (ET) 5 (ET-5) complex from other serogroup B strains, 30 serogroup B N. meningitidis isolates were subtyped by CFLP with internal fragments of five housekeeping genes, adk, aspC, carA, dhp, and glnA. Two genes (glnA and carA) which demonstrated a high degree of diversity for the serogroup B isolates were then used to further evaluate the suitability of CFLP for screening 50 serogroup C N. meningitidis outbreak-associated and sporadic-case isolates with a single metabolic gene. The results were compared to those from multilocus enzyme electrophoresis (MEE), the current standard subtyping method. CFLP was able to distinguish the ET-5 complex isolates from other serogroup B isolates as efficiently as MEE. Furthermore, CFLP analysis of a single gene was sufficient to identify and cluster the serogroup C isolates belonging to the ET-37 complex from other, unrelated serogroup C isolates but was not capable of differentiating between the isolates of the major individual ETs of this complex (ET-17 and ET-24) causing most serogroup C meningococcal disease outbreaks in the United States. CFLP based on a single gene with a high degree of diversity but not under selective pressure can be applied to the rapid screening of a large number of isolates related to the recognized epidemic complex ET-5 or ET-37. Additionally, CFLP can be used as an initial screening tool to survey the amount of diversity in genes that might be used to develop a DNA sequence-based subtyping system.