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Infection and Immunity, May 1999, p. 2138-2144, Vol. 67, No. 5
Gadi Research Centre, Faculty of Applied
Science, University of Canberra,1 and
Membrane Biochemistry Group, Division of Biochemistry and
Molecular Biology, John Curtin School of Medical Research,
Australian National University,2 Canberra
City, ACT 2601, Australia
Received 28 December 1998/Accepted 26 January 1999
Nontypeable Haemophilus influenzae (NTHI) is an
opportunistic pathogen, and heterogeneity in the surface-exposed
immunodominant domains of NTHI proteins is thought to be associated
with the failure of an infection to stimulate an immune response that
is cross-protective against heterologous NTHI strains. The aim of this
study was to assess the vaccine potential of a surface-exposed component of the NTHI human transferrin receptor, TbpB, and to determine if the antibody response elicited was cross-reactive with
heterologous strains of NTHI. The efficacy of immunization with a
recombinant form of TbpB (rTbpB) was determined by assessing the
pulmonary clearance of viable bacteria 4 h after a live challenge with NTHI. There was a significant reduction in the number of viable
bacteria in both the bronchoalveolar lavage fluid (34% for the 20-µg
dose and 58% for the 40-µg dose) and lung homogenates (26% for the
20-µg dose and 60% for the 40-µg dose) of rats immunized with
rTbpB compared to the control animals. While rTbpB-specific antibodies
from immunized rats were nonspecific in the recognition of TbpB from
six heterologous NTHI strains on Western blots, these antibodies
differed in their ability to block transferrin binding to heterologous
strains and to cross-react in bactericidal assays. If bactericidal
antibodies are key indicators of the efficacy of the immune response in
eliminating NTHI, this data suggests that while immunization with rTbpB
stimulates protective responses against the homologous isolate,
variability in the recognition of TbpB from heterologous isolates may
limit the potential of rTbpB as an NTHI vaccine component.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Immunization with Recombinant Transferrin
Binding Protein B Enhances Clearance of Nontypeable
Haemophilus influenzae from the Rat Lung
*
Corresponding author. Present address: Leukocyte
Signalling and Regulation Laboratory, John Curtin School of Medical
Research, Australian National University, P.O. Box 334, Canberra City,
ACT 2601, Australia. Phone: (61) 6 2492267. Fax: (61) 6 2490415. E-mail: Dianne.Webb{at}anu.edu.au.
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