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Prevalence of genetic differences in phosphorylcholine expression between nontypeable Haemophilus influenzae and Haemophilus haemolyticus.
- Source :
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BMC microbiology [BMC Microbiol] 2010 Nov 12; Vol. 10, pp. 286. Date of Electronic Publication: 2010 Nov 12. - Publication Year :
- 2010
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Abstract
- Background: Although non-typeable (NT) Haemophilus influenzae and Haemophilus haemolyticus are closely related human commensals, H. haemolyticus is non-pathogenic while NT H. influenzae is an important cause of respiratory tract infections. Phase-variable phosphorylcholine (ChoP) modification of lipooligosaccharide (LOS) is a NT H. influenzae virulence factor that, paradoxically, may also promote complement activation by binding C-reactive protein (CRP). CRP is known to bind more to ChoP positioned distally than proximally in LOS, and the position of ChoP within LOS is dictated by specific licD alleles (designated here as licDI, licDIII, and licDIV) that are present in a lic1 locus. The lic1 locus contains the licA-licD genes, and ChoP-host interactions may also be influenced by a second lic1 locus that allows for dual ChoP substitutions in the same strain, or by the number of licA gene tetranucleotide repeats (5'-CAAT-3') that reflect phase-variation mutation rates.<br />Results: Using dot-blot hybridization, 92% of 88 NT H. influenzae and 42.6% of 109 H. haemolyticus strains possessed a lic1 locus. Eight percent of NT H. influenzae and none of the H. haemolyticus strains possessed dual copies of lic1. The licDIII and licDIV gene alleles were distributed similarly (18-22%) among the NT H. influenzae and H. haemolyticus strains while licDI alleles were present in 45.5% of NT H. influenzae but in less than 1% of H. haemolyticus strains (P < .0001). NT H. influenzae had an average of 26.8 tetranucleotide repeats in licA compared to 14.8 repeats in H. haemolyticus (P < .05). In addition, NT H. influenzae strains that possessed a licDIII allele had increased numbers of repeats compared to NT H. influenzae with other licD alleles (P < .05).<br />Conclusions: These data demonstrate that genetic similarities and differences of ChoP expression exist between NT H. influenzae and H. haemolyticus and strengthen the hypothesis that, at the population level, these differences may, in part, provide an advantage in the virulence of NT H. influenzae.
- Subjects :
- Amino Acid Sequence
Bacterial Proteins chemistry
Bacterial Proteins metabolism
Gene Expression Regulation, Bacterial
Haemophilus chemistry
Haemophilus metabolism
Haemophilus Infections microbiology
Haemophilus influenzae chemistry
Haemophilus influenzae metabolism
Humans
Molecular Sequence Data
Sequence Alignment
Bacterial Proteins genetics
Haemophilus genetics
Haemophilus influenzae genetics
Phosphorylcholine metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1471-2180
- Volume :
- 10
- Database :
- MEDLINE
- Journal :
- BMC microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 21073698
- Full Text :
- https://doi.org/10.1186/1471-2180-10-286