High-Resolution Melting (HRM) for rapid MLST analysis of Neisseria meningitidis

The genetic characterization of meningococcal isolates is extremely important for the epidemiological monitoring of meningococcal disease, through the identification of circulating epidemic clones, with the purpose of supporting specific actions of Health Surveillance to contain outbreaks. The objective of this work is to determine a strategy for the epidemiological control of Neisseria meningitidis (Nm) through the detection of genetic signatures of Multilocus Sequence Typing (MLST) genes, by the method of high-resolution DNA melting analysis (qPCR-HRM), to identify the main hypervirulent clones circulating in the country. We analyzed 65 cc103 strains, 19 cc11, 38 cc32 and 8 cc41/44 and 17 were not associated to a specific cc. For the abcZ gene a total of 112 strains were tested, 79 for adk and gdh genes, 87 for aroE, 27 for fumC and 70 strains for pdhC gene. The results obtained were compared and validated with nucleotide sequencing. The percentage of correct allele detection for each clonal complex ranged between 77% and 100%. After an active search in PubMLST, it was found that by inserting results from at least 4 alleles in the MLST database, it is possible to determine the clonal complex of 99% to 100% of the deposited samples. The results obtained in this study suggest that it is possible to identify Nm clonal complexes by a combination analysis of melting curves (TM) of four constitutional genes included in the MLST scheme by qPCR-HRM.