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Assessing Respiratory Immune Responses to Haemophilus Influenzae
06:32

Assessing Respiratory Immune Responses to Haemophilus Influenzae

Published on: June 29, 2021

Haemophilus parainfluenzae has a limited core lipopolysaccharide repertoire with no phase variation

Rosanna E B Young1, Derek W Hood

  • 1Department of Paediatrics, University of Oxford, Oxford, UK. r.young@ucl.ac.uk

Glycoconjugate Journal
|October 25, 2012
PubMed

Insights

Lipopolysaccharide (LPS) structures differ between Haemophilus influenzae and H. parainfluenzae, impacting bacterial-host interactions. H. parainfluenzae lacks phosphocholine, a key virulence factor in H. influenzae.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Cell surface lipopolysaccharide (LPS) is a critical virulence factor in Haemophilus influenzae.
  • Investigating LPS in the less pathogenic Haemophilus parainfluenzae offers insights into species-specific virulence.

Purpose of the Study:

  • To compare the lipopolysaccharide (LPS) biosynthesis genes and structures between Haemophilus influenzae and Haemophilus parainfluenzae.
  • To understand the implications of LPS differences on bacterial-host interactions and pathogenic potential.

Main Methods:

  • Analysis of 18 commensal H. parainfluenzae isolates for LPS biosynthesis genes.
  • Comparison of gene sets with H. influenzae LPS genes.
  • Immunoblotting using antibodies against selected LPS epitopes.
  • Genetic manipulation to introduce H. influenzae LPS genes into H. parainfluenzae.

Main Results:

  • H. parainfluenzae shares inner core LPS biosynthesis genes with H. influenzae but has fewer outer core genes.
  • Homologues of specific H. influenzae LPS genes were identified in some H. parainfluenzae isolates.
  • No evidence of tetranucleotide repeat-mediated phase variation was found in H. parainfluenzae.
  • Phosphocholine, a virulence-associated epitope in H. influenzae, was absent in H. parainfluenzae LPS.
  • Introduction of H. influenzae lic1 genes into H. parainfluenzae resulted in phase-variable phosphocholine incorporation.

Conclusions:

  • Inner core LPS biosynthesis is largely conserved between H. influenzae and H. parainfluenzae.
  • Outer core LPS gene prevalence and structure differ significantly, potentially influencing pathogenicity.
  • Absence of phosphocholine in H. parainfluenzae LPS may contribute to its lower virulence compared to H. influenzae.

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