Distribution of transferrin binding protein B gene (tbpB) variants among Neisseria species.
BACKGROUND
Transferrin binding protein B (tbpB), an outer membrane lipoprotein, is required for the acquisition of iron from human transferrin. Two tbpB families have been documented in Neisseria meningitidis: an isotype I tbpB gene of 1.8 kb and an isotype II tbpB gene of 2.1 kb, the former expressed by meningococci in the disease-associated ST-11 clonal complex and the latter found among meningococci belonging to the hyper-invasive clonal complexes including ST-8, ST-18, ST-32, ST-41/44 as well as N. gonorrhoeae isolates. The origin of the isotype I tbpB gene is unknown, however several features in common with non-pathogenic Neisseria and the ST-11 clonal complex N. meningitidis isolate FAM18 have been documented leading to the hypothesis that the isotype I tbpB gene may also be shared between non-pathogenic Neisseria and ST-11 meningococci. As a result, the diversity of the tbpB gene was investigated in a defined collection of Neisseria species.


RESULTS
Two families of isotype I tbpB were identified: family A containing conserved genes belonging to ST-11 meningococci, N. polysaccharea and N. lactamica isolates and family B including more diverse isotype I tbpB genes from N. sicca, N. mucosa, N. flava, N. subflava as well as N. cinerea, N. flavescens and N. polysaccharea isolates. Three isotype II tbpB families were identified with: family C containing diverse tbpB genes belonging to N. polysaccharea, N. lactamica, N. gonorrhoeae and N. meningitidis isolates, family D including another subset of isotype II tbpB genes from N. lactamica isolates and family E solely composed of N. gonorrhoeae tbpB genes.


CONCLUSIONS
This study reveals another instance of similarity between meningococci of the ST-11 clonal complex and non-pathogenic Neisseria with the origin of the isotype I tbpB gene resulting from a horizontal genetic transfer event occurring between these two populations.
Harrison
Odile B
OB
The Peter Medawar Building for Pathogen Research and Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3SY, UK. odile.harrison@zoo.ox.ac.uk
Maiden
Martin C J
MC
Rokbi
Bachra
B
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D044822:Biodiversity; D006069:Gonorrhea / Q000382:microbiology; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D009343:Neisseria / Q000145:classification / Q000235:genetics*; D016870:Neisseriaceae Infections / Q000382:microbiology; D010802:Phylogeny; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D033882:Transferrin-Binding Protein B / Q000737:chemistry / Q000235:genetics*
D001426:Bacterial Proteins; D020033:Protein Isoforms; D033882:Transferrin-Binding Protein B