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Infection and Immunity, May 2001, p. 2972-2979, Vol. 69, No. 5
Departments of Oral
Microbiology,1 Preventive
Dentistry,2 and Oral Science
Methodology3 and Division of Special
Care Dentistry,4 Osaka University Graduate
School of Dentistry, Suita-Osaka, Japan
Received 3 November 2000/Returned for modification 28 December
2000/Accepted 7 February 2001
Lys-gingipain (KGP), a lysine-specific cysteine proteinase, is one
of the major virulence factors of Porphyromonas gingivalis. Here we examined the involvement of the catalytic domain of KGP (KGPcd) in hemoglobin binding by P. gingivalis,
using a specific immunoglobulin G (IgG) elicited by the administration
of plasmid DNA encoding KGPcd or the catalytic domain of
Arg-gingipain (RGPcd). The
pSeq2A/kgpcd and
pSeq2B/rgpcd plasmids were constructed by the
ligation of kgpcd and
rgpcd DNA fragments, respectively. Female BALB/c mice were immunized with each of these plasmids.
pSeq2A/kgpcd elicited a strong response to
recombinant KGPcd (rKGPcd), as well as to
comparably produced rRGPcd-reactive antibodies. The serum antibodies elicited by pSecTag2B/rgpcd also
cross-reacted with rKGPcd as well as rRGPcd.
Anti-KGPcd IgG significantly inhibited hemoglobin binding
by P. gingivalis. Furthermore, the inhibition of hemoglobin
binding was markedly enhanced by a combination of anti-KGPcd and anti-fimbriae. Anti-RGPcd IgG
showed a negligible inhibitory effect, while both
anti-KGPcd and anti-RGPcd IgGs showed significant inhibitory effects on Lys- and Arg-specific proteolytic activities and on the growth of P. gingivalis under
iron-restricted conditions where supplemented hemoglobin was the sole
iron source. Immunized mice were challenged by intraperitoneal
inoculation with P. gingivalis. All nonimmunized mice died
within 72 h; however, vaccination with
pSeq2A/kgpcd and
pSeq2B/rgpcd prevented inflammatory responses
and prolonged the survival rate of immunized mice by 43 and 27%,
respectively. These results suggest that KGPcd acts as a
hemoglobin-binding protein and can also be useful as an immunogen inducing a protective response to P. gingivalis infection.
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.5.2972-2979.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Specific Antibodies to Porphyromonas gingivalis
Lys-Gingipain by DNA Vaccination Inhibit Bacterial Binding to
Hemoglobin and Protect Mice from Infection
*
Corresponding author. Mailing address: Department of
Oral Science Methodology, Osaka University Graduate School of
Dentistry, 1-8 Yamadaoka, Suita-Osaka 565-0871, Japan. Phone:
81-6-6879-2283. Fax: 81-6-6879-2976. E-mail:
amanoa{at}dent.osaka-u.ac.jp.
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