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Infection and Immunity, December 1999, p. 6335-6340, Vol. 67, No. 12
Departments of Medicine,1
Microbiology and Immunology,6
Pathology and Laboratory Medicine,7 and
Dermatology,2 Indiana University School
of Medicine, Indianapolis, Indiana 46202; Department of
Microbiology, State University of New York at Buffalo, New York
142143; and Children's Research
Institute4 and Department of Pediatrics
and Department of Medical Microbiology and
Immunology,5 Ohio State University, Columbus,
Ohio 43205-2696
Received 1 July 1999/Returned for modification 16 August
1999/Accepted 13 September 1999
The lipooligosaccharide (LOS) of Haemophilus ducreyi,
the etiologic agent of chancroid, chemically and immunologically
resembles human glycosphingolipid antigens. To test whether LOS that
contains paragloboside-like structures was required for pustule
formation, an isogenic mutant (35000HP-RSM2) was constructed in
losB, which encodes
D-glycero-D-manno-heptosyltransferase.
35000HP-RSM2 produces a truncated LOS whose major glycoform terminates
in a single glucose attached to a heptose trisaccharide core and
2-keto-3-deoxyoctulosonic acid. Five human subjects were inoculated
with 35000HP and 35000HP-RSM2 in a dose-response trial. For estimated
delivered doses (EDDs) of
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Expression of Sialylated or Paragloboside-Like
Lipooligosaccharides Are Not Required for Pustule Formation by
Haemophilus ducreyi in Human Volunteers
25 CFU, the pustule formation rates were
80% for 35000HP and 58% for 35000HP-RSM2. Preliminary data indicated
that a previously described Tn916 losB mutant made a minor
glycoform that does not require DD-heptose to form the
terminal N-acetyllactosamine. If 35000HP-RSM2 made this
glycoform, then 35000HP-RSM2 could theoretically make a sialylated
glycoform. To test whether sialylated LOS was required for pustule
formation, a second trial comparing an isogenic sialyltransferase
mutant (35000HP-RSM203) to 35000HP was performed in five additional
subjects. For EDDs of
25 CFU, the pustule formation rates were 30%
for both 35000HP and 35000HP-RSM203. The histopathology and recovery
rates of H. ducreyi from surface cultures and biopsies
obtained from mutant and parent sites in both trials were similar.
These results indicate that neither the expression of a major glycoform
resembling paragloboside nor sialylated LOS is required for pustule
formation by H. ducreyi in humans.
*
Corresponding author. Mailing address: Department of
Medicine, 435 Emerson Hall, 545 Barnhill Dr., Indiana University,
Indianapolis, IN 46202-5124. Phone: (317) 274-1427. Fax: (317)
274-1587. E-mail: sspinola{at}iupui.edu.
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