Phase-variable lipopolysaccharide structures enhance the invasive capacity of Haemophilus influenzae.
Genes necessary for the expression and phase variation of lipopolysaccharide epitopes of a virulent Haemophilus influenzae type b isolate (RM.7004) are contained within two chromosomal loci designated lic-1 and lic-2. Mutations were introduced into both lic-1 and lic-2, and the virulence of the double mutant was compared with that of the wild type in infant rats. These mutations in RM.7004 resulted in a significantly reduced incidence of bacteremia following intranasal inoculation, although nasopharyngeal colonization was similar for the mutant and wild-type strains. In contrast, no differences in bacteremia were observed when the mutant and wild-type strains were inoculated intraperitoneally.
Department of Paediatrics, University of Oxford, John Radcliffe Hospital, United Kingdom.
J N
JN
Weiser
A
A
Williams
E R
ER
Moxon
D000818:Animals; D002876:Chromosomes, Bacterial; D015169:Colony Count, Microbial; D006192:Haemophilus Infections / Q000209:etiology; D006193:Haemophilus influenzae / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D008070:Lipopolysaccharides / Q000235:genetics*; D009154:Mutation; D009305:Nasopharynx / Q000382:microbiology; D011897:Random Allocation; D051381:Rats; D011919:Rats, Inbred Strains; D015183:Restriction Mapping; D014774:Virulence
D008070:Lipopolysaccharides