title: The porA gene in serogroup A meningococci: evolutionary stability and mechanism of genetic variation.
abstract: Molecular analyses were applied to the genes encoding variants of the serosubtyping antigen, the class 1 outer membrane protein (PorA), from 55 serogroup A Neisseria meningitidis strains. These genes were evolutionarily stable and exhibited a limited range of genetic variation, primarily generated by recombination. Translation of the gene sequences revealed a total of 19 distinct amino acid sequences in the variable regions of the protein, 6 of which were not recognized by currently available serosubtyping monoclonal antibodies. Knowledge of these amino acid sequences permitted a rational re-assignment of serosubtype names. Comparison of the complete genes with porA gene sequences from serogroup B and C meningococci showed that serogroup A possessed a limited number of the possible porA genes from a globally distributed gene pool. Each serogroup A subgroup was characterized by one of four porA gene types, probably acquired upon subgroup divergence, which was stable over periods of decades and during epidemiological spread. Comparison with other variable genes (pil and iga) indicated that the three alleles were independently assorted within the subgroup, suggesting that their gene types were older than the subgroups in which they occurred.
authors.affiliation: National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, UK.
authors.forename: J
authors.initials: J
authors.lastname: Suker
authors.forename: I M
authors.initials: IM
authors.lastname: Feavers
authors.forename: M
authors.initials: M
authors.lastname: Achtman
authors.forename: G
authors.initials: G
authors.lastname: Morelli
authors.forename: J F
authors.initials: JF
authors.lastname: Wang
authors.forename: M C
authors.initials: MC
authors.lastname: Maiden
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology; D000940:Antigenic Variation; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001483:Base Sequence; D002681:China / Q000453:epidemiology; D004739:England / Q000453:epidemiology; D005798:Genes, Bacterial; D006801:Humans; D008585:Meningitis, Meningococcal / Q000453:epidemiology / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000145:classification / Q000235:genetics* / Q000276:immunology; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D018272:Porins / Q000235:genetics* / Q000276:immunology; D012689:Sequence Homology, Nucleic Acid; D012703:Serotyping
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins; D010446:Peptide Fragments; D018272:Porins; C057699:porin protein, Neisseria