INFECTION AND IMMUNITY, Apr. 2003, p. 2234–2238
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
Vol. 71, No. 4
Synergistic Protection of Mice against Plague with Monoclonal
Antibodies Specific for the F1 and V Antigens of Yersinia pestis
Jim Hill,* Catherine Copse,† Sophie Leary, Anthony J. Stagg,
E. Diane Williamson, and Richard W. Titball
Defence Science and Technology Laboratory, Porton Down, Wiltshire SP4 OJQ, United Kingdom
Received 6 August 2002/Returned for modification 26 September 2002/Accepted 11 December 2002
Monoclonal antibodies specific for Yersinia pestis V antigen and F1 antigen, administered singly or in
combination, protected mice in models of bubonic and pneumonic plague. Antibodies showed synergy when
administered prophylactically and as a therapy 48 h postinfection. Monoclonal antibodies therefore have
potential as a treatment for plague.
Yersinia pestis, the causative agent of plague, has accounted
for the deaths of millions of people throughout recorded his-
tory. The second pandemic (the Black Death) is thought to
have killed an estimated 17 to 28 million Europeans between
the 14th and 17th centuries. The third pandemic, believed to
have started in the Yunan Province of China in the 1850s, has
led to the worldwide spread of plague, which is now endemic to
several regions, including Africa, India, and the southwestern
states of the United States (25). Despite the current low inci-
dence of plague, the bacterium resides in natural animal res-
ervoirs, and regular, although relatively small, outbreaks of
plague occur (7, 19, 27). Improvements in transport links be-
tween areas of endemicity and large population centers bring
with them the potential for large-scale plague outbreaks, high-
lighted by the recent outbreak in India (33). There is therefore
a need for effective disease surveillance to reduce the risk of
plague transmission to new areas and subsequent outbreaks of
disease. Vaccination is recommended for research scientists
and other professionals who come into contact with the bac-
terium, but fast-acting treatments are also required for indi-
viduals exposed to Y. pestis in areas of endemicity or through
their work. In addition, after a major outbreak, there would be
a need to protect health care workers and first responders.
At present, protection against plague can be mediated
through vaccination or antibiotic treatment. Antibiotics are
used both to treat plague victims and as prophylaxis to control
the spread of the disease (25). The incidence of antibiotic re-
sistance in Y. pestis is low, but recent plague isolates in Mad-
agascar have been found to have multiple drug resistance, con-
ferred by a transferable plasmid (10, 11). Although the bacteria
were resistant to the frontline antibiotics streptomycin and
tetracycline, they were susceptible to additional antibiotics.
Existing plague vaccines include killed whole-cell prepara-
tions, and efforts to develop new vaccines are in progress (39).
Problems associated with whole-cell vaccines include relatively
low levels of protection, adverse side effects, slow time to im-
munity, and a need for regular booster immunizations (30). Al-
though whole-cell vaccines are thought to be effective against
the most common form of plague (bubonic plague), which
develops following a bite from an infected insect, their efficacy
against pneumonic plague has been questioned. Consequently,
whole-cell vaccines are no longer licensed for use in the United
States. Next-generation plague subunit vaccines, based on the
recombinant F1 and V (LcrV) antigen proteins derived from Y.
pestis, are being developed. Immunization with either protein
provides protection against pneumonic or bubonic disease in
animal models of infection (12, 17, 39), but greater-than-addi-
tive protection is achieved when F1 and LcrV are combined,
with protection against up to 109median lethal doses (MLD)
of Y. pestis reported (40). Such vaccines must be administered
prior to exposure, and multiple doses are required. Although
strategies to reduce the time to immunity and the number of
vaccine doses have shown promise (41), it is unlikely that vac-
cination will provide postexposure protection against disease.
There is therefore a need for alternative fast-acting antiplague
treatments to provide rapid protection, particularly to combat
drug-resistant strains of Y. pestis.
Because antisera have been used widely to treat a range of
diseases caused by other pathogens (15), we considered mono-
clonal antibodies (MAbs) as a treatment for plague. Previ-
ously, F1-04-A-G1, a mouse MAb raised against F1, was shown
to protect mice in models of bubonic and pneumonic plagues
(1). Also, preliminary studies showed that an LcrV-specific
MAb (MAb 7.3) protected mice in a bubonic plague model
(13). In this study, we considered the prophylactic and thera-
peutic properties of MAb 7.3, when administered alone and in
combination with F1-04-A-G1, to determine whether antibod-
ies could be used as a postexposure therapy for plague.
MAb 7.3 and F1-04-A-G1 were purified by ammonium sul-
fate precipitation from hybridoma supernatants. An equal vol-
ume of saturated ammonium sulfate solution was added slowly
to tissue culture supernatants, followed by overnight stirring at
4°C and then centrifugation at 3,000 ? g for 30 min. The pellets
were drained and resuspended in phosphate-buffered saline
(PBS; GIBCO, Paisley, United Kingdom) in 0.1 volume of the
original volume, which was then dialyzed against three changes
stead, United Kingdom) were packed with protein G-Sepha-
* Corresponding author. Mailing address: Defense Science and
Technology Laboratory, Porton Down, Wiltshire SP4 OJQ, United
Kingdom. Phone: 44 1980 614756. Fax: 44 1980 614 307. E-mail: jhill
† Present address: Amersham Biosciences, Amersham, Bucking-
hamshire HP7 9LL, United Kingdom.
rose beads (Sigma, Poole, United Kingdom), and antibody
solution was passed through the column. The beads were
washed with PBS, and then antibody was eluted with 50 mM
glycine (pH 3) and stored in fractions containing 150 ?l of Tris
HCl (pH 9.1) per 3 ml of eluate. Protein fractions were ana-
lyzed by sodium dodecyl sulfate-polyacrylamide gel electro-
phoresis (SDS-PAGE) on 10 to 15% Phastgels (Pharmacia,
Milton Keynes, United Kingdom), and fractions containing
antibody were dialyzed against three changes of PBS. Antibody
concentration was determined by bicinchoninic acid assay
(Perbio, Tattenhall, United Kingdom) with a bovine serum
albumin standard as recommended by the manufacturers. An-
tibody purity was assessed by SDS-PAGE analysis.
Antibodies were tested in murine models of bubonic and
pneumonic plagues. Six- to 8-week-old BALB/c mice were
used (Charles River, Ltd., Margate, United Kingdom). Animal
experiments were performed in accordance with United King-
dom legislation relating to animal experimentation (Animals
[Scientific Procedures] Act 1986).
Mice received antibody by intraperitoneal (i.p.) injection in
100 ?l of PBS prior to or after infection as indicated. Y. pestis
strain GB, a fully virulent human isolate, with an estimated
MLD of 1 CFU via the subcutaneous (s.c.) route (30), was used
in all challenge experiments. In the bubonic plague model,
mice received approximately 10 to 105MLD resuspended in
100 ?l of PBS, by s.c. injection. In the pneumonic plague
model, mice were exposed to approximately 100 MLD of air-
borne bacteria, as described previously (42). Animals were
checked at least twice daily, and deaths were recorded over a
MAb 7.3 protection. Mice were treated with purified MAb
7.3 24 h prior to challenge with 9.6 or 96 MLD of Y. pestis. As
little as 3.5 ?g of antibody protected mice and extended the
mean time to death (TTD) of animals that died (Table 1).
Greater survival was noted in groups given 10.5 or 35 ?g than
in those given 3.5 and 0.7 ?g of MAb 7.3. The degree of
protection was smaller in animals that received 96 MLD than
in those injected with 9.6 MLD (50 and 83% were survivors,
respectively). Therefore, protection against plague appeared to
be proportional to the amount of antibody administered and
was dependent on the challenge dose.
Five mice received 50 ?g of MAb 7.3 in 100 ?l of PBS by i.p.
injection. Mice were tail bled regularly over a 7-day period, and
levels of MAb 7.3 in serum were determined by anti-LcrV-
specific enzyme-linked immunosorbent assay (ELISA), as de-
scribed previously (13). These values were used to determine
the time taken for the serum antibody levels to fall to half in
individual animals; the average serum half-life was determined
as 5.6 days. Because the serum antibody level 28 days after
dosing was approximately 1.5 ?g, five immunized animals were
challenged with 18 MLD of Y. pestis. All MAb 7.3-treated
animals survived, whereas six of six untreated mice died. This
experiment demonstrated the potential for a single dose of
antibody as a long-lasting prophylactic.
MAb 7.3 was administered ?4, ?24, ?48, or ?96 h relative
to s.c. Y. pestis challenge. Protection was observed when anti-
body was given up to 48 h postinfection (Fig. 1A). Also, a
statistically significant delay in the TTD was observed in the
?96-h treatment group. One mouse in the ?96-h treatment
group had died prior to antibody administration, and the re-
mainder displayed signs of plague indistinguishable from those
in untreated control animals, suggesting that even when symp-
toms of plague are apparent, antibody therapy can delay death.
Mice were treated with MAb 7.3 at ?4, ?24, ?48, or ?60 h
relative to aerosol infection (Fig. 1B). Protection was seen in
groups that received antibody 24 and 48 h after challenge. All
mice treated at ?60 h died, but a statistically significant delay
in the TTD was observed, compared with that in untreated
animals (Fig. 1B).
Combined F1-04-A-G1 and MAb 7.3 treatment. Because re-
combinant F1 and LcrV provide greater-than-additive protec-
tion when administered as a subunit vaccine in mice (40), we
tested whether this was true for F1- and LcrV-specific antibod-
ies. F1-O4-A-G1 was administered i.p. singly (100 ?g) or in
combination with MAb 7.3 (35 ?g) in 100 ?g of PBS 4 h prior
to aerosol challenge with 88 MLD of Y. pestis. The various
treatments protected mice against plague as follows. Out of
each group of 10 mice, there were 0 survivors when treated
with PBS alone, 9 survivors when treated with F1-04-A-G1, 10
survivors when treated with MAb 7.3, and 9 survivors when
treated with F1-04-A-G1 plus MAb 7.3. Therefore, we con-
firmed the prophylactic properties of F1-04-A-G1 in the pneu-
monic plague model (1). MAb 7.3 was less effective as a treat-
ment against s.c. Y. pestis challenge than aerosol challenge
(Fig. 1), at least for the doses selected for each route; there-
fore, the bubonic plague model was chosen for further co-
administration studies to test for antibody synergy. First, anti-
bodies were tested as a pretreatment against challenge with
approximately 50 to 105MLD of Y. pestis GB (Table 2). Sur-
prisingly, protection was observed at all challenge doses;
breakthrough was expected at challenge doses greater than 100
MLD (Table 1) (1). Next, we tested the combined antibody
treatment as a plague therapy. Mice that received the antibody
cocktail 48 h after challenge with 91 MLD were protected
better than animals that received single-antibody therapy (Fig.
2). The data suggest that MAb 7.3 and F1-04-A-G1 act syner-
gistically as a pretreatment and as a therapeutic in our plague
Concluding remarks. We have demonstrated that MAbs
specific for Y. pestis surface proteins can be used as a therapy
for the treatment of plague. Mabs 7.3 and F1-04-A-G1 were
more effective as a therapy when combined than as single
TABLE 1. Dose-dependent protection against bubonic
plague with purified MAb 7.3
Concn of MAb
8.2 ? 1.1
4.8 ? 0.5
4.8 ? 0.3
6.3 ? 0.8
3.8 ? 2.7
6.4 ? 1.5
5.2 ? 0.4
4.1 ? 0.3
aMab 7.3 administered i.p. 24 h before challenge.
bY. pestis administered by s.c. injection in 100 ?l of PBS.
cValues are means ? standard error.
VOL. 71, 2003NOTES2235
treatments, when administered up to 2 days after s.c. Y. pestis
challenge. Together, the antibodies protected mice against an
s.c. challenge of 9.1 ? 104MLD when administered as a pre-
treatment. The data presented here mirror observations that
LcrV and F1 provide greater-than-additive protection when
included in plague subunit vaccines (12, 40). Vaccine-mediated
protection correlates with high specific polyclonal antibody
titers to F1 and LcrV (43), which agrees with our observation
that the degree of protection is proportional to the amount of
protective antibody administered (Table 1).
Passive transfer of LcrV-specific polyclonal antiserum pro-
tected mice against plague, and the protective epitopes were
assigned to region 168 to 275 (21). Similarly, we have mapped
MAb 7.3 binding to a conformational epitope between amino
FIG. 1. Therapeutic MAb 7.3 treatment of mice challenged with Y. pestis via the s.c. (A) and aerosol (B) infection routes. Mice received 35 ?g
of MAb 7.3 in PBS by i.p. injection 4 h before or up to 96 h after challenge with 46 (A) or 88 (B) MLD of Y. pestis. Deaths were recorded over
a 14-day period. A statistically significant delay in TTD was observed in animals treated with MAb 7.3 at 48 h (P ? 0.01) and 96 h (P ? 0.05)
post-s.c. challenge and 60 h (P ? 0.05) post-aerosol challenge by Student’s t test analysis (Microsoft Excel software).
TABLE 2. Enhanced protection with F1-04-A-G1 and MAb 7.3 as
a pretreatment against s.c. challenge
Y. pestis challenge
Untreated 46 0/6
F1-04-A-G1 ? Mab 7.3916/6
9.1 ? 102
9.1 ? 103
9.1 ? 104
aMice were immunized i.p. with 35 ?g of MAb 7.3 and 100 ?g of F1-04-A-G1
bPlague challenge (s.c.) 4 h after antibody administration.
2236 NOTESINFECT. IMMUN.
acids 135 to 275 of LcrV (13). Therefore, this central region of
LcrV appears to be a good target for plague-protective anti-
bodies. To date, epitope mapping studies have not been con-
ducted with F1-04-A-G1.
LcrV has a key role in type III secretion (TTS) by Yersinia
spp., a process that allows the injection of a set of effector
proteins directly into the cytosol of eukaryotic target cells upon
intimate contact (4, 14, 28, 29). The effector proteins (termed
“Yops”) have a range of functions that promote the killing of
phagocytic host cells. Protective polyclonal antisera inhibited
Yersinia TTS in HeLA cell cytotoxicity experiments, and LcrV
was detected at the bacterial surface prior to contact with
eukaryotic cells by confocal microscopy analysis (26). A similar
study showed that MAb 7.3, but not other nonprotective Mabs,
protected J774 macrophage-like cells against Yersinia-medi-
ated killing (37). Antiserum raised against the LcrV homo-
logue of Pseudomonas aeruginosa (PcrV) protected mice in a
lung infection model, antiserum inhibited TTS-mediated cyto-
toxicity of J774 cells (9, 31), and anti-PcrV F(ab?)2 fragment
provided therapeutic protection in a model of disease (32).
However, other studies did not show a correlation between
protective LcrV-specific polyclonal antiserum in cytotoxicity
assays (8). LcrV is also reported to have immunomodulatory
properties (20, 22, 34, 38), so it remains a possibility that
antibodies inhibit both TTS as well as the anti-inflammatory
properties of Y. pestis, by blocking the interaction of secreted
LcrV with an unidentified eukaryotic receptor.
F1 is expressed optimally at 37°C, is thought to inhibit
phagocytosis through the formation of a capsule-like structure
on the bacterial surface, and is an effective plague vaccine (2,
6, 12, 36). A recent report showed that an isogenic F1 plague
mutant has impaired resistance to phagocytosis by J774 cells
(6). Also, a virulence plasmid-cured strain, deficient for TTS,
was less resistant to phagocytosis, and an additive effect was
seen with the double mutant (F1-negative, plasmid-cured
strain). It was proposed that the TTS system and F1 capsule
synthesis contribute in different ways to maintain the extracel-
lular lifestyle of Y. pestis (6). The fact that we have targeted
both the TTS system and the F1 capsule might explain the high
level of protection achieved with MAbs 7.3 and F1-04-A-G1.
A number of strategies can be used to generate clinically
useful antibodies (3). For example, the specificity of animal
antibodies can be transferred to a human antibody framework,
a process termed “humanization” (35, 44), or animal antibod-
ies can be chemically treated to improve their therapeutic
properties (18). Alternatively, antibodies can be generated
from naïve human single-chain antibody libraries (5, 16, 24) or
from immunized transgenic animals that express a human an-
tibody repertoire (23). Our findings have highlighted the ben-
efits of combining antibodies specific for LcrV and F1. The
next challenge will be to identify further targets for antibody
intervention and to generate antibodies that are suitable for
clinical use as a fast-acting pretreatment or postexposure ther-
apy for plague.
We thank Robert Bull, NMRC, Bethesda, Md., for MAb F1-04-
A-G1 and acknowledge the support of Debbie Rogers, Helen Flick-
Smith, Chris LeButt, and Mark Brown.
1. Anderson, G. W., Jr., P. L. Worsham, C. R. Bolt, G. P. Andrews, S. L.
Welkos, A. M. Friedlander, and J. P. Burans. 1997. Protection of mice from
fatal bubonic and pneumonic plague by passive immunization with mono-
clonal antibodies against the F1 protein of Yersinia pestis. Am. J. Trop. Med.
2. Andrews, G. P., D. G. Heath, G. W. Anderson, Jr., S. L. Welkos, and A. M.
Friedlander. 1996. Fraction 1 capsular antigen (F1) purification from Yer-
sinia pestis CO92 and from an Escherichia coli recombinant strain and effi-
cacy against lethal plague challenge. Infect. Immun. 64:2180–2187.
3. Casadevall, A. 1999. Passive antibody therapies: progress and continuing
challenges. Clin. Immunol. 93:5–15.
4. Cornelis, G. R. 1998. The Yersinia deadly kiss. J. Bacteriol. 180:5495–5504.
5. de Haard, H. J., N. van Neer, A. Reurs, S. E. Hufton, R. C. Roovers, P.
Henderikx, A. P. de Bruine, J. W. Arends, and H. R. Hoogenboom. 1999. A
large non-immunized human Fab fragment phage library that permits rapid
isolation and kinetic analysis of high affinity antibodies. J. Biol. Chem.
6. Du, Y., R. Rosqvist, and A˚. Forsberg. 2002. Role of fraction 1 antigen of
Yersinia pestis in inhibition of phagocytosis. Infect. Immun. 70:1453–1460.
7. Duplantier, J. M., J. B. Duchemin, M. Ratsitorahina, L. Rahalison, and S.
Chanteau. 2001. Emergence of plague in the Ikongo District of Madagascar,
1998. 2. Reservoir and fleas involved. Bull. Soc. Pathol. Exot. 94:119–122.
8. Fields, K. A., M. L. Nilles, C. Cowan, and S. C. Straley. 1999. Virulence role
of V antigen of Yersinia pestis at the bacterial surface. Infect. Immun. 67:
9. Frank, D. W., A. Vallis, J. P. Wiener-Kronish, A. Roy-Burman, E. G. Spack,
B. P. Mullaney, M. Megdoud, J. D. Marks, R. Fritz, and T. Sawa. 2002.
Generation and characterization of a protective monoclonal antibody to
Pseudomonas aeruginosa PcrV. J. Infect. Dis. 186:64–73.
10. Guiyoule, A., G. Gerbaud, C. Buchrieser, M. Galimand, L. Rahalison, S.
Chanteau, P. Courvalin, and E. Carniel. 2001. Transferable plasmid-medi-
ated resistance to streptomycin in a clinical isolate of Yersinia pestis. Emerg.
Infect. Dis. 7:43–48.
11. Guiyoule, A., B. Rasoamanana, C. Buchrieser, P. Michel, S. Chanteau, and
E. Carniel. 1997. Recent emergence of new variants of Yersinia pestis in
Madagascar. J. Clin. Microbiol. 35:2826–2833.
12. Heath, D. G., G. W. Anderson, J. M. Mauro, S. L. Welkos, G. P. Andrews, J.
Adamovicz, and A. M. Friedlander. 1998. Protection against experimental
bubonic and pneumonic plague by a recombinant capsular F1-V antigen
fusion protein vaccine. Vaccine 16:1131–1137.
13. Hill, J., S. E. C. Leary, K. F. Griffin, E. D. Williamson, and R. W. Titball.
1997. Regions of Yersinia pestis V antigen that contribute to protection
against plague identified by passive and active immunization. Infect. Immun.
14. Hueck, C. J. 1998. Type III protein secretion systems in bacterial pathogens
of animals and plants. Microbiol. Mol. Biol. Rev. 62:379–433.
15. Keller, M. A., and E. R. Stiehm. 2000. Passive immunity in prevention and
treatment of infectious diseases. Clin. Microbiol. Rev. 13:602–614.
16. Knappik, A., L. M. Ge, A. Honegger, P. Pack, M. Fischer, G. Wellnhofer, A.
Hoess, J. Wolle, A. Pluckthun, and B. Virnekas. 2000. Fully synthetic human
combinatorial antibody libraries (HuCAL) based on modular consensus
frameworks and CDRs randomized with trinucleotides. J. Mol. Biol. 296:
17. Leary, S. E. C., E. D. Williamson, K. F. Griffin, P. Russell, S. M. Eley, and
R. W. Titball. 1995. Active immunization with recombinant V antigen from
Yersinia pestis protects mice against plague. Infect. Immun. 63:2854–2858.
FIG. 2. MAb 7.3 and F1-04-AG-1 display synergy when adminis-
tered postinfection. Mice were challenged s.c. with 91 MLD of Y. pestis
and treated 48 h after plague challenge with MAb 7.3 (35 ?g) or
F1-04-A-G1 (100 ?g) individually or together. Deaths were recorded
over a 14-day period.
VOL. 71, 2003NOTES2237
18. Mayers, C. N., J. L. Holley, and T. Brooks. 2001. Antitoxin therapy for
botulinum intoxication. Rev. Med. Microbiol. 12:29–37.
19. Migliani, R., M. Ratsitorahina, L. Rahalison, I. Rakotoarivony, J. B. Duch-
emin, J. M. Duplantier, J. Rakotonomenjanahary, and S. Chanteau. 2001.
Emergence of plague in the Ikongo District of Madagascar in 1998. 1. Epi-
demiological aspects in the human population. Bull. Soc. Pathol. Exot. 94:
20. Motin, V. L., S. M. Kutas, and R. R. Brubaker. 1997. Suppression of mouse
skin allograft rejection by protein A yersiniae V antigen fusion peptide.
21. Motin, V. L., R. Nakajima, G. B. Smirnov, and R. R. Brubaker. 1994. Passive
immunity to yersiniae mediated by anti-recombinant V antigen and protein
A-V antigen fusion peptide. Infect. Immun. 62:4192–4201.
22. Nakajima, R., V. L. Motin, and R. R. Brubaker. 1995. Suppression of cyto-
kines in mice by protein A-V antigen fusion peptide and restoration of
synthesis by active immunization. Infect. Immun. 63:3021–3029.
23. Neuberger, M., and M. Bruggemann. 1997. Monoclonal antibodies—mice
perform a human repertoire. Nature 386:25–26.
24. Nissim, A., H. R. Hoogenboom, I. M. Tomlinson, G. Flynn, C. Midgley, D.
Lane, and G. Winter. 1994. Antibody fragments from a ‘single pot’ phage
display library as immunochemical reagents. EMBO J. 13:692–698.
25. Perry, R. D., and J. D. Fetherston. 1997. Yersinia pestis—etiologic agent of
plague. Clin. Microbiol. Rev. 10:35–66.
26. Pettersson, J., A. Holmstrom, J. Hill, S. Leary, E. Frithz-Lindsten, A. von
Euler-Matell, E. Carlsson, R. Titball, A. Forsberg, and H. Wolf-Watz. 1999.
The V-antigen of Yersinia is surface exposed before target cell contact and
involved in virulence protein translocation. Mol. Microbiol. 32:961–976.
27. Ratsitorahina, M., S. Chanteau, L. Rahalison, L. Ratsifasoamanana, and P.
Boisier. 2000. Epidemiological and diagnostic aspects of the outbreak of
pneumonic plague in Madagascar. Lancet 355:111–113.
28. Rosqvist, R., A˚. Forsberg, and H. Wolf-Watz. 1991. Intracellular targeting of
the Yersinia YopE cytotoxin in mammalian cells induces actin microfilament
disruption. Infect. Immun. 59:4562–4569.
29. Rosqvist, R., K. E. Magnusson, and H. Wolf-Watz. 1994. Target-cell contact
triggers expression and polarized transfer of Yersinia YopE cytotoxin into
mammalian cells. EMBO J. 13:964–972.
30. Russell, P., S. M. Eley, S. E. Hibbs, R. J. Manchee, A. J. Stagg, and R. W.
Titball. 1995. A comparison of plague vaccine, Usp and Ev76 vaccine-in-
duced protection against Yersinia pestis in a murine model. Vaccine 13:1551–
31. Sawa, T., T. L. Yahr, M. Ohara, K. Kurahashi, M. A. Gropper, J. P. Wiener-
Kronish, and D. W. Frank. 1999. Active and passive immunization with the
Pseudomonas V antigen protects against type III intoxication and lung injury.
Nat. Med. 5:392–398.
32. Shime, N., T. Sawa, J. Fujimoto, K. Faure, L. R. Allmond, T. Karaca, B. L.
Swanson, E. G. Spack, and J. P. Wiener-Kronish. 2001. Therapeutic admin-
istration of anti-PcrV F(ab?)(2) in sepsis associated with Pseudomonas
aeruginosa. J. Immunol. 167:5880–5886.
33. Shivaji, S., N. V. Bhanu, and R. K. Aggarwal. 2000. Identification of Yersinia
pestis as the causative organism of plague in India as determined by 16S
rDNA sequencing and RAPD-based genomic fingerprinting. FEMS Micro-
biol. Lett. 189:247–252.
34. Sing, A., A. Roggenkamp, A. M. Geiger, and J. Heesemann. 2002. Yersinia
enterocolitica evasion of the host innate immune response by V antigen-
induced IL-10 production of macrophages is abrogated in IL-10-deficient
mice. J. Immunol. 168:1315–1321.
35. Taylor, G., J. Furze, P. R. Tempest, P. Bremner, F. J. Carr, and W. J. Harris.
1991. Humanized monoclonal-antibody to respiratory syncytial virus. Lancet
36. Titball, R. W., A. M. Howells, P. C. F. Oyston, and E. D. Williamson. 1997.
Expression of the Yersinia pestis capsular antigen (F1 antigen) on the surface
of an aroA mutant of Salmonella typhimurium induces high levels of protec-
tion against plague. Infect. Immun. 65:1926–1930.
37. Weeks, S., J. Hill, A. Friedlander, and S. Welkos. 2002. Anti-V antigen
antibody protects macrophages from Yersinia pestis-induced cell death and
promotes phagocytosis. Microb. Pathog. 32:227–237.
38. Welkos, S., A. Friedlander, D. McDowell, J. Weeks, and S. Tobery. 1998. V
antigen of Yersinia pestis inhibits neutrophil chemotaxis. Microb. Pathog.
39. Williamson, E. D. 2001. Plague vaccine research and development. J. Appl.
40. Williamson, E. D., S. M. Eley, K. F. Griffin, M. Green, P. Russell, S. E. C.
Leary, P. C. F. Oyston, T. Easterbrook, K. M. Reddin, A. Robinson, and
R. W. Titball. 1995. A new improved subunit vaccine for plague—the basis
of protection. FEMS Immunol. Med. Microbiol. 12:223–230.
41. Williamson, E. D., S. M. Eley, A. J. Stagg, M. Green, P. Russell, and R. W.
Titball. 2000. A single dose subunit vaccine protects against pneumonic
plague. Vaccine 19:566–571.
42. Williamson, E. D., S. M. Eley, A. J. Stagg, M. Green, P. Russell, and R. W.
Titball. 1997. A subunit vaccine elicits IgG in serum, spleen cell cultures and
bronchial washings and protects immunized animals against pneumonic
plague. Vaccine 15:1079–1084.
43. Williamson, E. D., P. M. Vesey, K. J. Gillhespy, S. M. Eley, M. Green, and
R. W. Titball. 1999. An IgG1 titre to the F1 and V antigens correlates with
protection against plague in the mouse model. Clin. Exp. Immunol. 116:107–
44. Winter, G., and W. J. Harris. 1993. Humanized antibodies. Trends Pharma-
col. Sci. 14:139–143.
Editor: D. L. Burns