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Cell Biology Department, Albert Einstein College of Medicine, Bronx, NY 10461
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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> J
>> VH > JH > D. Further screening of a
peptide library with anti-P601E mAbs isolated peptides having a
motif almost identical to the peptide motif selected by 2H1. When these
results are compared to the crystal structure of a related peptide in
complex with 2H1, there is a clear correlation between the ability to
elicit V region components of 2H1 Ab and peptide association with the V
region, suggesting that the completeness of the fit in the binding site
is an important driving force for mimicry. As a consequence, improving
affinity of a mimetic for the Ab binding site seems to be the most
logical way to insure that all of the appropriate V region segments are
elicited and that useful mimotopes are created. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Based on the crystallographic study of different complexes between an anti-lysozyme Ab, lysozyme, and anti-idiotypic Abs (3), it has been suggested that mimicry is functional in reproducing the binding interactions between the Ag and the Ab, thus validating the idea of molecular image. Nevertheless, it is not clear whether such a model would be true for small molecules, especially when the contact surface is not large and flat as in the lysozyme case. Moreover, it is unclear whether a mimotope must be structurally similar to the original Ag and whether there is a systematic way to obtain the best mimotopes.
Recently, a number of laboratories have examined whether peptides can also serve as mimotopes. Since peptides are simpler molecules, it was anticipated that the cross-reactive immune response would be easier to characterize and to manipulate. Peptides provide the potential of focusing the immune response on epitopes that will mediate protection against infectious agents and avoiding epitopes that may not be useful or might even elicit blocking Abs (12) or Abs to self components. The reduction of protein structures to smaller antigenic parts, as well as production of sets of molecular variants capable of protecting against antigenic variations (mixotopes (2)), makes mimotopes a promising avenue for vaccine development.
In the present work, we analyze the immune response to a potential
peptide mimotope (P601E) of a complex polysaccharide that was isolated
by screening a phage display peptide library with an Ab1 Ab, and
compare it with the crystal structure of a related peptide in complex
with the same selecting Ab (4). Cryptococcal glucuronoxylomannan
(GXM)3 is the major antigenic
determinant of the capsule of Cryptococcus neoformans, an
encapsulated opportunistic fungus responsible for a high incidence of
life-threatening meningoencephalitis in immunocompromised patients (5, 6). This polysaccharide is largely responsible for the virulence of the
organism (reviewed in 7 and consists of a complex repetitive
structure (8) for which synthetic derivatives have not been reported.
mAbs to GXM, elicited either by a tetanus toxoid conjugate or during
the course of infection, are highly restricted in BALB/c mice to
VH7183 and VK5.1 (9, 10, 11). These mAbs differ
from each other in the sequences of complementarity-determining region
3 (CDR3) of VH and the presence of a limited number of
somatic mutations, and they exhibit varied properties in terms of
epitope recognition and ability to confer protection (9, 12). The
screening of 6-mer and 10-mer phage peptide libraries by 2H1, a highly
protective IgG1/ mAb, isolated numerous peptides represented by two
main motifs: motif 1, (E)TPXWM/LM/L, and motif 2, W/YXWM/LYE (13). All
of these peptides compete with GXM for binding to 2H1. Phage 
601
(SYSWMYE) was isolated from the hexapeptide library but is in fact
heptameric, due to a G to E mutation in the C-terminal linker that is
involved in the binding to 2H1 (13). This peptide belongs to motif 2
and is of low affinity (14). Motif 2 peptides are in general of lower
affinity than motif 1 peptides, but a few of them react with a large
set of protective anti-GXM Abs, suggesting that they define a
common protective epitope on GXM (9, 12). This study was conducted with
a synthetic equivalent P601E (DGASYSWMYEA) of the peptide insert of
601.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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P601E peptide (NH2-DGASYSWMYEA) was synthesized by the Laboratory for Macromolecular Analysis of the Albert Einstein College of Medicine; biotinylated P601E (biotin-SGSGDGASYSWMYEA) was prepared by Chiron Mimotopes Peptide Systems (San Diego, CA); the P315 control peptide (NH2-CKVMVHDPHSLA) is a gift of Dr. Stanley Nathenson (Albert Einstein College of Medicine, Bronx, NY). Unless otherwise indicated, immunologic reagents were from Southern Biotechnology (Birmingham, AL). Anti-m13 phage Abs were from 5-prime, 3-prime, Inc. (Boulder, CO). Streptavidin was from Sigma (St. Louis, MO).
Immunization and hybridomas
Peptides P601E and P315 were conjugated to keyhole limpet hemocyanin (KLH) and BSA with glutaraldehyde as previously described (15). Five 6- wk-old BALB/c mice (National Cancer Institute, Bethesda, MD) were immunized i.p. with 100 µg of P601E conjugated to KLH in emulsion with CFA at day 0, and IFA at day 27 and 56. Bleedings were done at day -1 before immunization and 3 wk after each boost. Mice were boosted again 4 days before fusion of the splenocytes with NSO myeloma cells at a ratio of 4:1 (16). The hybridomas were generated in the Hybridoma Facility of the Albert Einstein Cancer Center. Hybridoma supernatants were screened by ELISA either on P601E/BSA conjugate-coated plates (mouse 3) or on biotinylated P601E peptide bound to streptavidin coated plates (mouse 4). To assay hybridomas in the latter fusion, plates were coated overnight at 4°C with 50 µl streptavidin, 1 µg/ml, followed, after blocking and washing steps, by 50 µl of 1 µg/ml biotinylated peptide for 2 h at 37°C.
ELISA and serum study
ELISAs for binding to cryptococcal polysaccharide (GXM-A, strain
NIH 371, a gift from Dr. A. Casadevall) or to peptides on phage are
described in detail elsewhere (14, 17). Briefly, detection of GXM
binding used a three-layer sandwich consisting of GXM adsorbed to the
well, Abs to be tested, and a mixture of anti- and anti-
light chain Abs conjugated to alkaline phosphatase at a dilution of
1:250 and 1:500, respectively. The background signal of prebleed
samples at each serum dilution was subtracted. Detection of peptide
binding was done by direct ELISA (14) using a four-layer sandwich
consisting of anti-m13 Ab, phage, Abs to be tested, and
anti-mouse light chain Abs conjugated to alkaline phosphatase.
Phage 33, which displays the linkers but contains no peptide
insert, was used as a negative control in all phage ELISAs. Sera were
serially diluted starting at 1:50, and mAbs were used at 2 µg/ml.
Rabbit polyclonal anti-2H1 Id Ab was prepared by G. Nussbaum (18).
Briefly, a New Zealand white rabbit was immunized with mAb 2H1 in CFA.
Rabbit antiserum was repeatedly adsorbed on murine IgG1/ coupled to
Sepharose 4B (Pharmacia Biotech, Uppsala, Sweden). Polyclonal antiserum
was further immunopurified by affinity chromatography using a chimeric
2H1 Ab containing human constant regions, kindly provided by Dr. Sherie
Morrison (University of California, Los Angeles, CA). Rabbit
anti-2H1 Id anti-serum was detected with a goat anti-rabbit
IgG Ab conjugated to alkaline phosphatase (Fisher Scientific,
Orangeburg, NY).
mRNA sequence determination
Total RNA from hybridoma cells (5–10 x 106) was extracted by using an Ultraspec RNA kit from Biotecx (Houston, TX). After reverse transcription with AMV reverse transcriptase and the primer MS24 (5'-GGGGCCAGTGGATAGAC) according to the manufacturer’s recommendations (Boehringer Mannheim, Indianapolis, IN), VH- and VL-encoding cDNAs were selectively amplified by PCR. A set of degenerate oligonucleotides from Dubel and coworkers (19) was used to prime the 5' region of the genes: primers Bi3, Bi3b, Bi3c, and Bi4 for VH; and Bi5, Bi7, and Bi8 for VL. Each PCR reaction contained 3 µl of cDNA synthesis reaction, 100 pmol of each primer, 200 µM of each dNTP, 1x PCR buffer, and 1 U of Taq DNA polymerase (Boehringer Mannheim) and was cycled 35 times for 1 min at 95°C, 1 min at 53°C, and 1 min at 72°C. Amplified V genes were ligated to the TA cloning vector (Invitrogen, San Diego, CA) and the ligation product was used directly to transform DH10B heat shock-competent bacteria (Life Technologies, Gaithersburg, MD). Colonies were screened by blue/white selection and for the presence of an insert of the correct size. Insert DNAs from positive clones were sequenced in both directions on an automatic DNA sequencer at the DNA Sequencing Facility of the Cancer Center of the Albert Einstein College of Medicine using SP6 and T7 promoter primers, 5'-CAAGCTATTTAGGTGACACTATAGA and 5'-TAATACGACTCACTATAGGG, respectively.
D element determination
D elements were attributed with the help of the Immunogenetics database (world wide web site: http://imgt.cnusc.fr:8104s/).
Peptide phage library screening
The L100 decapeptide library is derived from the fUSE5 vector
and contains 400 million decapeptides fused at the N-terminal sequence
of the pIII fd phage coat protein with overall sequence
ADGSGGX10GAPSG. The construction of this library was
previously reported, except that an error in the sequence has now been
corrected (13). For each mAb, 50 library equivalents were used for the
initial library screening. Only one cycle of selection was performed
for each mAb. In the initial step, 15 µg of mAb was reacted with 7.5
µg of biotinylated anti-mouse 
1 chain Ab (2b for mAbs 124
and 431) for 30 min at room temperature in biopanning buffer (Tris/HCl,
10 mM, pH 7.5; NaCl, 150 mM; BSA, 0.1% w/v; Tween 20, 0.1% v/v; and
NaN3, 0.02% w/v). Fifty microliters of streptavidin-coated
magnetic beads (Advanced Magnetics, Cambridge, MA) were added
and the incubation was continued for 30 min. Free biotin binding sites
were blocked with 5 µl of D-biotin, 100 mM (Sigma).
Subsequent procedures, including phage selection, preparation of
intermediate libraries, immunologic screening on plates, virion
preparation, and sequencing were identical to those described with mAb
2H1 (13).
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Results |
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P601E was first conjugated to BSA. The IgG1 2H1 mAb bound tightly
to the P601E/BSA conjugate but not to the control peptide P315/BSA
conjugate. The IgG1 mAb 2D10 that failed to bind to the phage 601
(13) showed no reactivity with either the P601E or the control P315/BSA
conjugate (data not shown). This pattern of reactivity attests to a
correct coupling of the peptide P601E, probably by its terminal free
amine, as expected with glutaraldehyde. The corresponding P601E/KLH
conjugate was shown to bind 2H1 and was used to immunize five mice i.p.
Mice were also immunized with either a control peptide conjugate,
P315/KLH (5 mice), or GXM conjugated to tetanus toxoid, GXM-TT (2.5
µg/mouse; 5 mice) (11). The binding of the sera from the mice
immunized to phage 601 by direct ELISA (14) is presented in Figure 1
. After immunization, all mouse sera
reacted strongly with phage 601 but not with the control phage,
33. In addition, the serum of mouse 4 reacted with a polyclonal
rabbit anti-idiotypic Ab to 2H1 (data not shown). However, no
reactivity with GXM was detected by ELISA with any of the
anti-peptide sera (Fig. 1). The sera from P315/KLH mice did not
react with GXM; sera from mice immunized with GXM-TT had an average OD
of 1.2 at the 1:50 dilution and an average titer of 1:12,800 defined by
the serum dilution giving a signal that was half of the maximum
absorbance.
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The spleen cells of mouse 3 and 4 were fused to NSO myeloma cells.
Hybridoma supernatants from the mouse 3 fusion were screened against
P601E conjugated to BSA. Eleven mAbs were isolated. However, only two
of them, 3A10 and 4A11, were inhibited in their binding by free P601E
peptide (data not shown). Both of these Abs were 2H1 Id negative. The
other mAbs reacted with the control peptide P315/BSA conjugate,
suggesting that they recognized the glutaraldehyde linker. These latter
mAbs were not studied further. Mouse 4 was chosen as an example of a
response in which the anti-peptide Abs expressed the 2H1 Id. To
detect only anti-peptide mAbs, hydridoma supernatants from mouse 4
fusion were screened only for mAbs that bound biotinylated P601E on
streptavidin-coated plates. Twelve hybridomas making mAbs of 1,
2a, and 2b isotypes were obtained (only IgG was screened). All of
these mAbs reacted with 601, but not GXM, and most reacted with a
rabbit immunopurified anti-2H1 Id antiserum (Table I).
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(GenBank
accession numbers AF015195–AF015222). mAb 4A11 resembles 2H1 in using
the same germline genes, a member of the 7183 VH family for
the heavy chain and a V5.1 for the light chain (Table I
). mAb 18
VH is encoded by a member of the VH11 family
and its light chain by V45.1. The V region V45.1 is highly
homologous to the 2H1 light chain V5.1 from which it differs at the
amino acid level at only four positions (Fig. 2B), including
one in CDR1 and one in CDR3. All other mAbs showed a restricted gene
usage of a combination of V45.1 and members of the
VH36–60 gene family (Table I). Most of the 12
VH36–60 sequences, except mAbs 147, 409, and 546, are
strongly homologous to one of the known germline genes of the
VH36–60 gene family (GenBank accession number m73891
(21)). mAbs 147, 409, and 546 use J5, which distinguished them from
the other mAbs (Fig. 2A), share the same JH
element, and have the same junctional diversity in both light and heavy
chains, suggesting that they are the progeny of a single B cell. They
all differ from the other VH36–60 mAbs at a few positions
(nucleotide positions 88, 138, 147, 155, 156, 201, and 212; Fig. 2A). Although we cannot rule out the possibility that these
nucleotide changes are the result of shared somatic mutations, taken
together, they suggest that this particular B cell used a different
germline gene of the VH36–60 family that has not yet been
reported. The VH36–60 family contains at least five
germline genes (22), but nucleotide sequences have not been reported
for all of them.
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) and use different D elements (Table I). They are thus different from
anti-GXM Abs such as 2H1 that have a constant 11-amino acid-long
CDR3. Taken together, gene usage and heavy chain CDR3 sequence define,
for the 12 Abs generated from mouse 4, five subgroups of mAbs, each one
potentially deriving from a single parent B cell: mAbs 147, 409, and
546 already noted above; mAbs 544, 124, and 752; mAbs 234, 638, 316,
and 717; mAb 431; and finally, mAb 18, which is the only mAb from mouse
4 that uses a VH gene that is not from the
VH36–60 family (Fig. 2 and Table I).
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Since the anti-P601E mAbs did not bind GXM, we asked whether
they shared fine specificity characteristics with 2H1. A panel of 10
phage selected by 2H1, which we had used previously to define the fine
specificity of a large panel of anti-GXM Abs (13), was reacted with
each of the mAbs. The peptides displayed by these 10 phage represent
peptide motifs 1 and 2 described above as well as two other motifs that
bind 2H1 at lower affinities. By direct ELISA on phage (14), all mAbs
derived from VH36–60 and V45.1 reacted only with phage
601, which expressed the immunizing peptide (Table I). In contrast,
mAb 18 bound phage 601 and phage G3, both of which bear a motif 2
peptide W/YXWM/LYE. mAb 4A11, which uses the same VH and
VL gene families as 2H1, displayed a still wider spectrum
of reactivity including binding to phage A1, A3, and B4, all
of which display motif 1 (E)TPXWM/LM/L.
To obtain additional information on the binding site of the mAbs
elicited by P601E and to determine whether or not they recognized P601E
in a similar way to 2H1, we screened our decapeptide library with mAbs
4A11, 3A10, 18, and 124, which represent each of the anti-P601E mAb
VH/V pairings that we observed (Table I). Since
selection conditions of high stringency would ultimately yield phage
bearing peptides very analogous to the eliciting peptide P601E, only
one round of selection was performed at very low stringency, in which
phage yields were identical for low and high binders (between 40 and
60%). We observed phage yields (percentage of phage rescued from the
original library) between 0.24 x 10-2% (mAb 124)
and 5.45 x 10-2% (mAb 18). When the immunologic
screening of colonies on plates was made more sensitive by adding an
excess of anti- Ab to increase the avidity of binding by the mAb
(14), >95% of the clones selected in a single cycle were positive for
each selecting mAb. In the absence of the anti--enhancing Ab,
only a few of the mAbs were positive, showing that phage with a wide
range of affinities had been selected (14). Five phage clones were
randomly chosen for each mAb and their peptide inserts sequenced; 14 of
20 clones gave readable sequence ladders. Alignment with the immunizing
peptide P601E was possible with 12 inserts (Table III). Of these, 7 did not give a positive
signal by ELISA on phage and were therefore of low affinity (data not
shown) (14). Recurrences between the amino acids in these new peptides
and P601E occurred most frequently in the central hexapeptide YSWMYE,
with the highest rate for tryptophan W7 (100%), methionine
M8 (83%), and tyrosine Y9 (42%); the glycine
G2 has a high recurrence of 42%, which probably
results from the presence of two glycines in the N-terminal linker
surrounding the peptide insert. The serine S6 is relatively
well represented (33%) and appears associated mainly with the usage of
a VH36–60 family member. Aromatic residues have a high
recurrence (83%) at positions Y5 and Y9. This
is also the case for the 2H1 motif 2, and at this level, homologies are
more striking. The positions corresponding to the triple aromatic amino
acid repeat have a high occurrence (on average 83%) of aromatic
residues, and the triple aromatic residue motif ArXArXAr by itself
appears in 75% of the inserts. The dipeptide WM is present in >90%
of the peptides that match P601E. This dipeptide is present in both the
2H1 peptide motif 1, (E)TPXWM/LM/L, and motif 2, W/YXWM/LYE. The
glutamate E10, which also belongs to the motif 2, has a
lower occurrence and is probably less involved in the binding of P601E
to the anti-P601E mAbs. Overall, anti-P601E mAbs have a
peptide-binding motif ArXWMY that is almost identical to 2H1 motif 2,
except for the presence of a C-terminal negatively charged amino acid.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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All anti-P601E mAbs used either the same 2H1 light chain, V5.1,
or the related V45.1, which differs by only four amino acids, an E
to H change in CDR1, an S to T change in CDR3, and two changes in
framework region 3 (Fig. 2B). Like the VL gene,
the light chain J elements were similar, since J1 is used by 2H1 and
also by five of seven B cell progenitors, which produced anti-P601E
Abs (Table I). On the other hand, the heavy chain sequences exhibit a
higher degree of diversity. Only one mAb (4A11) has a VH
belonging to the VH7183 family that is used by all of the
BALB/c anti-GXM Abs that we have studied (11). This Ab, therefore,
has an identical VH-V pair as 2H1. Most other mAbs use
members of the VH36–60 family, except one that uses a
member of the V11 family (mAb 18). The JH
elements show a preferential use of JH4 in association with
a member of the VH36–60 family and overall do not use
JH2, which is used by 2H1. The length of the CDR3 varies
from 8 to 13 amino acids, compared with the constant 11-amino acid-long
CDR3 of the anti-GXM mAbs of the 2H1 family (11). Moreover, the
dipeptide RD at the beginning of the heavy chain CDR3, which
characterizes all anti-GXM mAbs (11), is not found in any of the
anti-peptide Abs. Taken together, these data indicate that 2H1 and
anti-P601E mAbs elicited in BALB/c mice have a decreasing order of
homology of V > J >> VH > JH > D.
The Ab binding site of 2H1 is a hydrophobic pocket delimited by the
CDRs 2 and 3 of the heavy chain and 1 and 3 of the light chain (4).
When complexed with 2H1, the peptide PA1 (LQYTPSWMLV) of motif 1 adopts
a tightly coiled conformation composed of an inverse -turn and a
type II ß-turn. As a result, the lateral chains of the 2H1-selected
motif residues are grouped together in a tight cluster that is inserted
into the Ab cavity. The analogy between motifs 1 and 2 suggested that
this was a common binding feature for both motifs (4). Therefore, a
more precise way to explore the characteristics of the anti-P601E
mAb binding site was to test mAbs elicited by P601E for binding to
peptides selected by 2H1. Extensive cross-reactivity between
anti-P601E Abs and 2H1-selected phage appeared only for mAb 4A11,
which has a similar pairing V5.1/VH7183 as 2H1. Other
Abs only recognized 601, with the exception of mAb 18, which also
binds the G3 of the same motif. Screening of the peptide library
with the anti-P601E mAbs was more informative. The strong
similarity of the peptide motif selected by the anti-P601E mAb with
the 2H1 selected motif 2 suggests a similar mechanism for recognition
of P601E. During the screening of the hybridoma supernatant from mouse
3 fusion, we isolated numerous Abs that in fact were reacting with
different parts of the peptide, but that involved the
glutaraldehyde linker. With mouse 4 fusion, we restricted the screening
to the mAbs that were cross-reactive with a biotinylated version of
P601E. All of the isolated mAbs also recognized phage 601.
Therefore, although P601E may have many conformations in solution, the
immune system of BALB/c mice has chosen to recognize only one of them.
The anti-P601E peptide motif, in fact, differs from the 2H1 motif 2 by the absence of a negatively charged amino acid on the C-terminal end. The presence of this motif residue is associated with the presence of an arginine at the beginning of the D region of all anti-GXM mAbs (4), which is probably an important structural determinant for binding GXM. Examination of the crystal structure of the 2H1/PA1 complex reveals peculiar binding characteristics (4). In constrast to other known Ab structures in complex with a peptide, the fit of the P601E surface with the Ab binding site surface is imperfect. There is a tight fit between the peptide and the light chain, while there are several cavities between the peptide and the heavy chain, including CDR3. Although a C-terminal negatively charged amino acid is required for motif 2 peptide binding, that amino acid probably does not make strong contacts with the surface cavity of the Ab. Anti-P601E mAbs probably either do not recognize this residue or recognize it in a conformation that is different from the conformation seen in the 2H1 complex and thus differ from anti-GXM Abs in an important recognition determinant.
When we compare our results with the entire 2H1/peptide complex, there is a clear relationship between the ability to elicit V segments used in the original 2H1 mAb and the presence of a tight fit in the binding pocket. Since we do not have the structure of GXM in complex with 2H1, we cannot compare the binding interactions of the original Ag and the peptide mimetic with 2H1. Nevertheless, our observation suggests that, in the case of a pocket-like Ab, a peptide mimetic will have to fit tightly in the area of the Ab surface that is responsible for binding the Ag to be an effective mimotope that will elicit high titer Ab to the original Ag. This conclusion is similar to that reached by Fields et al. for a protein Ag such as the lysozyme for which the Ab binding site is large and relatively flat (see the introduction) (3). However, this may be even more important for nonpeptide Ags (20, 24). To elicit anti-GXM Abs, we may therefore have to identify peptides that fit tightly throughout the Ab binding site. By generating peptides of higher affinity, we should be able to improve the completeness of the fit and test our hypothesis. Accordingly, preliminary results obtained by immunization with the peptide PA1, which has a higher affinity than P601E (13), show the presence of some Abs that cross-react with GXM, encouraging us to seek peptides with still higher affinities.
In conclusion, the study of the immune response to a peptide mimetic of a nonpeptidic Ag shows that, despite a low affinity for the parent Ab, the response to that peptide uses light chain variable region genes very similar to those used for the parental Ag. Since this low affinity peptide interacts with a limited part of the binding pocket that includes the light chain CDRs, we hypothesize that extending the area of close contact by identifying peptides with increased affinity for the Ab could provide mimotopes that will elicit anti-GXM Abs. Such peptide mimotopes could focus the immune response on epitopes that mediate protection.
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Matthew D. Scharff, Albert Einstein College of Medicine, Cell Biology Department, 1300 Morris Park Avenue, Bronx, NY 10461.
3 Abbreviations used in this paper: GXM, glucuronoxylomannan; Ar, aromatic amino acid; CDR, complementarity-determining region; KLH, keyhole limpet hemocyanin; , phage.
Received for publication November 12, 1997. Accepted for publication April 14, 1998.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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D. O. Beenhouwer, R. J. May, P. Valadon, and M. D. Scharff High Affinity Mimotope of the Polysaccharide Capsule of Cryptococcus neoformans Identified from an Evolutionary Phage Peptide Library J. Immunol., December 15, 2002; 169(12): 6992 - 6999. [Abstract] [Full Text] [PDF]
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K.-Y. Lee, H. G. Kim, M. R. Hwang, J. I. Chae, J. M. Yang, Y. C. Lee, Y. K. Choo, Y. I. Lee, S.-S. Lee, and S.-I. Do The Hexapeptide Inhibitor of Galbeta 1,3GalNAc-specific alpha 2,3-Sialyltransferase as a Generic Inhibitor of Sialyltransferases J. Biol. Chem., December 13, 2002; 277(51): 49341 - 49351. [Abstract] [Full Text] [PDF]
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 T. Jouault, C. Fradin, F. Dzierszinski, M. Borg-Von-Zepelin, S. Tomavo, R. Corman, P.-A. Trinel, J.-P. Kerckaert, and D. Poulain Peptides that mimic Candida albicans-derived {beta}-1,2-linked mannosides Glycobiology, August 1, 2001; 11(8): 693 - 701. [Abstract] [Full Text] [PDF]
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A. Nakouzi, P. Valadon, J. Nosanchuk, N. Green, and A. Casadevall Molecular Basis for Immunoglobulin M Specificity to Epitopes in Cryptococcus neoformans Polysaccharide That Elicit Protective and Nonprotective Antibodies Infect. Immun., May 1, 2001; 69(5): 3398 - 3409. [Abstract] [Full Text] [PDF]
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R. Fleuridor, A. Lees, and L.-a. Pirofski A Cryptococcal Capsular Polysaccharide Mimotope Prolongs the Survival of Mice with Cryptococcus neoformans Infection J. Immunol., January 15, 2001; 166(2): 1087 - 1096. [Abstract] [Full Text] [PDF]
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S. L. Harris, M. K. Park, M. H. Nahm, and B. Diamond Peptide Mimic of Phosphorylcholine, a Dominant Epitope Found on Streptococcus pneumoniae Infect. Immun., October 1, 2000; 68(10): 5778 - 5784. [Abstract] [Full Text] [PDF]
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P. Luo, G. Canziani, G. Cunto-Amesty, and T. Kieber-Emmons A Molecular Basis for Functional Peptide Mimicry of a Carbohydrate Antigen J. Biol. Chem., May 19, 2000; 275(21): 16146 - 16154. [Abstract] [Full Text] [PDF]
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