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The genome sequences of Neisseria meningitidis serogroup B strain MC58 and serogroup A strain Z2491 were systematically searched for open reading frames (ORFs) encoding autotransporters. Eight ORFs were identified, six of which were present in both genomes, whereas two were specific for MC58. Among the identified ORFs was the gene encoding the known autotransporter IgA1 protease. The deduced amino acid sequences of the other identified ORFs were homologous to known autotransporters and found to contain an N-terminal signal sequence and a C-terminal domain that could constitute a beta-barrel in the outer membrane. The ORFs NMB1985 and NMB0992, encoding homologs of the Hap (for Haemophilus adhesion and penetration protein) and Hia (for Haemophilus influenzae adherence protein) autotransporters of H. influenzae, were cloned from serogroup B strain H44/76 and expressed in Escherichia coli. Western blots revealed that all sera of patients (n=14) and healthy carriers (n=3) tested contained antibodies against at least one of the recombinant proteins. These results indicate that both genes are widely distributed among N. meningitidis isolates and expressed during colonization and infection

PorA is an important component in a vaccine against infection with Neisseria meningitidis. However, porA-negative meningococci were isolated from patients, thereby potentially limiting the role of PorA-mediated immunity. To analyze the mechanism by which the porA deletion occurred, the regions upstream and downstream of porA from three meningococcal strains (H44/76, H355, and 860183) were sequenced. The porA upstream region in strain 860183 contains a cluster of 22 repetitive palindromic RS3 core sequences (ATTCCC-N8-GGGAAT) and 10 RS3 core sequences (ATTCCC) in direct orientation. The cluster is flanked by neisserial repeats, so-called Correia elements, and can be subdivided into three repeats of 518 bp followed by a truncated repeat. The porA upstream region of the other two strains showed deletions, probably caused by a recombination between RS3 core sequences. The porA downstream region of H44/76 and H355 contains the IS1106 element followed by a cluster of 10 palindromic RS3 core sequences, 4 RS3 core sequences, and 1 other RS3 core sequence (GGGAAT) and is followed by a Correia element. This cluster can be subdivided into four direct repeats of 370 bp. Strain 860183 had two such repeats instead of four. Sequence analysis of the porA-negative variants indicated that the deletion of porA occurred via a recombination between two copies of the 116-bp region, containing two palindromic RS3 core sequences and a single RS3 core sequence. This region is homologous in the upstream and downstream clusters

In the study that is described the sensitivities and specificities of three commercial tests and the standard Reference Laboratory test, used since 1961, to identify Neisseria meningitidis serogroups were compared. The tests marketed by Difco, Murex/Wellcome, and Sanofi/Pasteur showed overall sensitivities of 92, 95, and 100%, respectively, and specificities of 67, 88, and 82%, respectively. When limited to the common serogroups A, B, and C, the three tests yielded sensitivities of 93, 97, and 100%, respectively, and specificities of 98, 100, and 98%, respectively. However, determination of the uncommon serogroups X, W-135, Y, Z, and 29E with these tests is either unreliable or not possible