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Infection and Immunity, September 2000, p. 5090-5095, Vol. 68, No. 9
Biotechnology Laboratory, University of
British Columbia, Vancouver, British Columbia, Canada V6T
1Z3,1 and Division of Microbiology,
Ottawa Hospital Civic Campus, Ottawa, Ontario, Canada KIY
4E92
Received 10 April 2000/Returned for modification 9 May
2000/Accepted 2 June 2000
Vaccination has been proposed for the prevention of disease due to
enterohemorrhagic Escherichia coli (EHEC), but the immune response following human infection, including the choice of potential antigens, has not been well characterized. To study this, sera were
obtained from five pediatric patients with acute diarrhea caused by
E. coli O157:H7 0, 8, and 60 days after hospitalization. These sera were used to examine the immune response to four different EHEC virulence factors: Tir (translocated intimin receptor, which is
inserted into the host cell membrane), intimin (bacterial outer membrane protein which binds to Tir), EspA (secreted protein which forms filamentous structures on EHEC surface), and EspB (inserted into
the host membrane and cytoplasm). The response to O157:H7 lipopolysaccharide was also examined. Sera were assayed against purified recombinant proteins using immunoblot analysis and by enzyme-linked immunosorbent assay to determine the sera's titers to
each of the antigens in all patients. We found that there was little
reaction to EspA, EspB, and intimin in the acute-phase sera, although
there was some reactivity to Tir. By day 8, titers of antibody to all
four virulence factors were present in all patients, with a very strong
response against Tir (up to a titer of 1:256,000), especially in
hemolytic-uremic syndrome patients, and lesser strong responses to the
other three antigens. The titer to the antigens 60 days after
hospitalization was decreased but was still highest for Tir. These
results suggest that there is a strong immune response to Tir, and to a
lesser extent to the other three virulence factors, following EHEC
disease, indicating that these bacterial molecules are potential
vaccine candidates for preventing EHEC disease. They also suggest that
bacterial virulence factors that are inserted into host cells during
infection by type III secretion systems (Tir or EspB) are still
recognized by the host immune response.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Human Response to Escherichia coli
O157:H7 Infection: Antibodies to Secreted Virulence Factors
and
*
Corresponding author. Mailing address: Biotechnology
Laboratory, University of British Columbia, Room 237-Wesbrook Building, 6174 University Blvd., Vancouver, British Columbia, Canada
V6T-1Z3. Phone: (604) 822-2210. Fax: (604) 822-9830. E-mail:
bfinlay{at}interchange.ubc.ca.
Present address: Child and Youth Clinical Trial Network,
Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada KIH 8L1.
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