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Infection and Immunity, August 2000, p. 4593-4597, Vol. 68, No. 8
Division of Otologic Research, College of
Medicine and Public Health, The Ohio State University, Columbus,
Ohio 43210
Received 10 March 2000/Returned for modification 26 April
2000/Accepted 11 May 2000
Nontypeable Haemophilus influenzae (NTHI) has four
loci, lic-1 to lic-3 and lgtC, that
generate phase-variable lipooligosaccharide (LOS) structures.
lic-1, which is required for the expression of
phosphorylcholine (ChoP), is the best characterized and is associated
with an enhanced ability of H. influenzae to persist within
the nasopharynges of infant rats. Recent data indicate that LOS impacts
various aspects of NTHI virulence in the chinchilla model of
nasopharyngeal colonization and otitis media (OM). In this study the
effects of ChoP expression and the sequences of lic-1 to
lic-3 and lgtC of NTHI strain 2019 were
evaluated in the chinchilla OM model. Nasopharyngeal colonization data
showed that a switch from the ChoP
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Evaluation of Phase Variation of Nontypeable
Haemophilus influenzae Lipooligosaccharide during
Nasopharyngeal Colonization and Development of Otitis Media in the
Chinchilla Model
to the
ChoP+ phenotype was observed as early as day 3 after
intranasal inoculation. Chinchillas colonized by strains with the
ChoP+ phenotype demonstrated a significantly higher level
of NTHI 2019 per milliliter of nasal lavage fluid than chinchillas
colonized with predominantly the ChoP
variant
(P < 0.05). The concentration of cells with the
ChoP+ phenotype in the middle ear was 3 log units higher
than that of cells with the ChoP
variant
(P < 0.01). There was a statistically significant
association between ChoP+ expression in the nasal lavage
and the development of OM with culture-positive middle ear fluids in
this model. These data suggest that expression of the ChoP+
phenotype promotes enhanced nasopharyngeal colonization and development of OM.
*
Corresponding author. Mailing address: Division of
Otologic Research, The Ohio State University, College of Medicine and
Public Health, Room 4331 UHC, 456 W. 10th Ave., Columbus, OH 43210. Phone: (614) 293-8103. Fax: (614) 293-5506. E-mail:
demaria.2{at}osu.edu.
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