The Journal of Immunology, 1999, 162: 6963-6966.
Copyright © 1999 by The American Association of Immunologists
Cutting Edge: Silencing Virus-Specific Cytotoxic T Cell-Mediated Immune Recognition by Differential Splicing: A Novel Implication of RNA Processing for Antigen Presentation1
Norbert Kienzle2,
Tom B. Sculley,
Sonia Greco and
Rajiv Khanna
EBV Unit, Queensland Institute of Medical Research, and University of Queensland Joint Oncology Program, Brisbane, Australia
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Abstract
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Persistent viruses have developed potent strategies to overcome
host immune defenses. In particular, viral interference with Ag
presentation by HLA class I molecules can effectively impair the
hosts CTL function. Here we provide evidence for a novel aspect of
differential splicing on endogenous processing of a latent viral
transcript resulting in dominant protein isoforms from which the CTL
determinant has been deleted. Consequently, virus-infected cells
expressing these isoforms were poorly recognized by CTLs. Molecular
analysis revealed that this splicing significantly reduced expression
of the viral transcript encoding the relevant epitope to levels below
the threshold required for CTL recognition. The importance of splicing
was further reinforced by the observation of efficient CTL recognition
of target cells expressing a truncated viral transcript that abolished
differential splicing. Thus, differential splicing, which is a common
mechanism of gene regulation in many pathogens, may unexpectedly
interfere with immune recognition.
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Introduction
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The
success of persistent viruses lies in their capacity for evading the
host defense mechanisms by either mutating target Ags or interfering
with components of the host immune response. In particular, viral
interference with HLA-restricted CTL response is a potent immune
evasion strategy resulting in reduction or loss of CTL function (1). In
the case of persistent herpes virus infections, such as EBV, many of
the target epitopes for CTLs are included within some of the latent
viral Ags (2). However, it is tempting to speculate that general
regulatory mechanisms of gene expression may mask potential T cell
determinants within other viral Ags. Of particular interest is one of
the EBV-encoded BamHI A transcripts (referred to as
RK-BARF0) (3) which is ubiquitously expressed in all EBV-associated
malignancies such as Burkitts lymphoma
(BL)3 and
nasopharyngeal carcinoma (NPC) (4), making this Ag a potential target
for CTL control. Indeed, we have recently reported that RK-BARF0
encodes the HLA-A*0201-restricted CTL epitope LLWAARPRL, which
stimulates CTLs from healthy virus carriers, albeit at a low CTL
precursor frequency (5). Although these RK-BARF0-specific CTLs
effectively recognized target cells exogenously sensitized with the
LLWAARPRL synthetic peptide, EBV-infected B cells were not lysed in a
standard 51Cr release assay. This lack of
endogenous presentation of this epitope opens the possibility that EBV
utilizes a mechanism to mask expression of ubiquitously expressed viral
proteins that might threaten viral persistence.
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Materials and Methods
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Cell lines
Both the EBV-positive BL cell lines (MutuI c59 and MutuIII c62)
and lymphoblastoid cell lines (LCLs) (NK-Wil and SB-B95.8) transformed
with EBV strains QIMR-Wil (6) or B95.8 (7) are HLA-A2 positive. DG75 is
an EBV-negative, HLA-A2-positive BL cell line. The EBV-positive NPC
cell lines C15 (HLA-A2 negative) and C17 (HLA-A2 positive) were a gift
from P. Busson (Institute Gustave Roussy, Villejuif, France). B cell
lines were maintained in RPMI 1640 with 10% FCS (growth medium) and
are described elsewhere (8).
Generation of plasmids and transfected cells
Plasmid pE-BARF0 containing the BARF0 open reading frame (ORF)
in the expression vector EBO-pLPP was reported recently (5). The Flag
epitope-tagged cDNA sequence of RK-BARF0 (a gift from N. Raab-Traub,
University of North Carolina, Chapel Hill, NC) was also cloned into the
vector EBO-pLPP. Conditions for cell transfection have been reported
recently (5), and polyclonal cell cultures were maintained with 600 or
150 µg hygromycin B (Boehringer Mannheim, Indianapolis, IN) per ml of
growth medium for DG75 or LCL transfectants, respectively.
Establishment of the RK-BARF0-specific CTL clone C1
CTL clones were generated from PBMC of donor NK (EBV/HLA-A*0201
positive) as described previously (9). Briefly, donor cells were
stimulated with
-irradiated autologous LCLs which were stably
transfected with plasmid pE-BARF0 expressing the BARF0 ORF. T cell
clones were grown in soft agar and expanded by cocultivation with the
stimulator cells, and CTL clone RK-BARF0 C1 was selected. The
specificity of this clone toward the HLA-A2-restricted peptide
LLWAARPRL was defined with a standard 51Cr
release assay with PHA blasts which were exogenously sensitized with
synthetic peptides and in a cold target inhibition assay. FACScan
analysis demonstrated that clone C1 was >98% CD3/CD8 positive. T cell
cultures were maintained in growth medium supplemented with recombinant
IL2 as described previously (9).
Cytotoxicity assay
Target cells, either untreated, plasmid transfected, or peptide
sensitized, were incubated with 51Cr for 90 min
followed by the addition of effector cells in a standard 5-h
51Cr release assay (9).
RT-PCR analysis and sequencing
A detailed description for the preparation, DNase I treatment,
and oligo(dT) primer-based reverse transcription of total cellular RNA
as well as for the PCR conditions used was outlined recently (5, 8).
The following PCR primers were used to amplify EBV sequences with 32 or
35 PCR cycles (the position within the EBV strain B95.8 (7) is given in
parentheses): BARF0-F, 5'-GCCCGAGGAGCTGTAGACC (160308); LLW-F,
5'-TGTCCAGCGCTCTGGTCG (160586); BARF2-R, 5'-CCACGGCAAC CCTTCCAC
(160812). The ß2-microglobulin primers
ß2-M5' (5'-CCCCCACTGAAAAAGATGAG) and
ß2-M3' (5'-TCACTCAATCCAAATGCGGC) as well as
the ß-actin primers 0016 (5'-CACAGAGCCTCGCCTTTG) and 0017
(5'-TGGATAGCAACGTACATG) were used in 23 PCR cycles. The PCR protocol
was as follows: 5 min denaturation at 95°C; cycles of 1 min at
95°C, 30 s at 60°C, 1 min at 72°C; followed by 5 min extension at
72°C. The PCR products were separated and visualized by
electrophoresis on a 2.5% agarose gel containing ethidium bromide. The
gel was photographed under UV light, and the film was analyzed on a
Computing Densitometer 300 B system (Molecular Dynamics, Sunnyvale,
CA). The isolated cDNA products were cloned with the pGEM-T vector
system (Promega, Madison, WI) and sequenced with the PRISM Reader
DyeDeoxy terminator cycle sequencing kit (Applied Biosystems, Foster
City, CA) and M13 primers.
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Results and Discussion
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Differential splicing silences the endogenous presentation of a
viral CTL epitope
CTL lines that recognized the HLA class I-restricted epitope
LLWAARPRL encoded in the RK-BARF0 gene did not kill EBV-positive BL
cells or LCLs that expressed RK-BARF0 (5). In this study, we explored
the possibility that increased expression of the RK-BARF0 protein in
EBV-infected B cells might restore RK-BARF0-specific CTL recognition.
Thus, the HLA-A2-positive LCL NK was stably transfected with the
plasmid pE-F-RKBARF0 (referred to as NK(E-F-RKBARF0)) which encodes the
full length RK-BARF0 sequence, N-terminally tagged with the Flag
epitope (Fig. 1
A).
Surprisingly, neither NK(E-F-RKBARF0) nor the vector control (NK(E))
transfectants were recognized by the RK-BARF0-specific CTL clone C1 in
a standard 51Cr release assay (Fig. 1
B). Similar results were also obtained using other
HLA-A2-positive LCLs and EBV-positive BL cell lines as targets and
polyclonal effector CTL lines specific for the LLWAARPRL epitope. This
lack of killing was not due to impaired HLA-A2 expression by the NK LCL
transfectants given that exogenous loading of LLWAARPRL peptide
onto these target cells induced CTL-mediated killing (Fig. 1
B). Moreover, FACScan analysis with the use of the
HLA-A2-specific mAb MA2.1 demonstrated high levels of HLA-A2 expression
on the NK cell transfectants (data not shown). To check expression of
the Flag-tagged RK-BARF0 protein in the cell transfectants, immunoblot
analysis was used incorporating an anti-Flag mAb (Fig. 1
C). The expected full length 32-kDa RK-BARF0 protein was
detected in the NK(E-F-RKBARF0) cells but not in the control cells
(NK(E)). However unexpectedly, the majority of Flag-tagged proteins
were truncated 16- to 20-kDa proteins.

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FIGURE 1. LCLs expressing RK-BARF0 are not killed by a RK-BARF0-specific CTL
clone. A, Schematic diagram of plasmid pE-F-RKBARF0
with the SV40 promotor ( ) driving transcription of the N-terminally
Flag-tagged RK-BARF0 cDNA. The Flag epitope (shown as a flag), the RK
exon ( ), the BARF0 ORF ( ), the in frame sequence ( ) located 5'
before BARF0, and the CTL epitope (thick black line) are illustrated.
B, 51Cr release assay using
RK-BARF0-specific CTL clone C1. The LCL NK stably transfected with
either plasmid pE-F-RKBARF0 (NK(E-F-RKBARF0)) or control vector
(NK(E)), respectively, as well as NK(E) and NK(E-F-RKBARF0) cells
exogenously coated with peptide LLWAARPRL (LLW) were used as targets at
different E:T ratios. C, Immunoblot analysis. Total cell
extracts of the LCL NK stably transfected with plasmid pE-F-RKBARF0
(lane 1) or a control vector (lane 2)
were separated by a 12% SDS-PAGE. Protein expression was analyzed by
immunoblot using an anti-FLAG Ab (8). Molecular size markers (kDa)
are shown on the right, and the positions of the full length protein
(F-RKBARF0) and the splice variants (F-S#13) are indicated by
arrows.
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One possible explanation for both the immunoblot result and the lack of
killing of RK-BARF0 transfectants may relate to posttranscriptional
processing of this transcript. To address this issue, RT-PCR was
performed with the use of RNA from the NK(E-F-RKBARF0) cell line and
BARF0-specific primers (BARF0-F and BARF2-R) (Fig. 2
B). This analysis revealed a
surprising splicing pattern of the RK-BARF0 mRNA. The major products
were splice cDNAs of 350 and 400/410 bp, whereas the full length 700-bp
cDNA (which includes the LLWAARPRL epitope) was virtually undetectable
(Fig. 2
A, lane 6). Sequencing of the RT-PCR
products demonstrated that the differently spliced transcripts encoded
three protein isoforms (150, 190, and 177 aa) the molecular masses of
which correlated well with the observed mass of the 16- to 20-kDa
truncated Flag proteins detected in Fig. 1
C. This
observation was reinforced by a similar splicing pattern in a panel of
EBV-positive BL (MutuI, MutuIII), LCL (NK, SB), and NPC (C15) cell
lines (Fig. 2
A). Cloning and sequencing of the isolated cDNA
products demonstrated three distinct splicing events which used a
common 5'-splice site and three different 3'-splice sites with virtual
perfect homology to the mammalian consensus splice sequences
(summarized in Fig. 2
B). These splice variants encoded two
truncated RK-BARF0 proteins (S#1, S#2) and a frame-shifted chimeric
protein product (S#3), all of which lacked the LLWAARPRL epitope
sequence. These data demonstrated that differential splicing
significantly reduced the full length transcript that included the CTL
epitope.

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FIGURE 2. Differential splicing removes the RK-BARF0 CTL epitope.
A, RT-PCR assay for RK-BARF0 expression in EBV-positive
cells. Total RNA was reverse transcribed from the LCLs NK (1), SB (2),
the BL cell lines MutuI (3) and MutuIII (4), the NPC cell line C15 (5),
and NK(E-F-RKBARF0) transfectants (6) in the presence (+) or absence
(-) of RT enzyme and oligo(dT) primers. The RT samples, the water
control (H2O), and the positive control DNA of plasmid
pE-F-RKBARF0 (DNA) were PCR amplified using primers BARF0-F and
BARF2-R. The 1-kbp DNA marker ladder (M) is shown, and the position of
the unspliced and spliced cDNA variants (S#13) is indicated by
arrowheads. Densitometric analysis revealed that only low amounts
(between 0.5 and 22% of the cDNA population) of full length transcript
was produced in the different cell lines. B, Schematic
diagram of the RK-BARF0 organization and splicing in EBV. The numbering
(in base pairs) refers to the EBV BamHI A sequence of
strain B95.8 (7), and start, stop, and splice sites are indicated. The
RK exon ( ), the BARF0 ORF ( ), the in frame sequence ( ) located
5' before BARF0, the CTL epitope (thick black line), and the position
and orientation of the primers used for RT-PCR are illustrated. The
splice pattern of the cDNA variants, the spliced out sequences (capital
letters), the coding sequences (small letters), and the splice points
() are shown. The splice sequences are given and compared with the
mammalian consensus splice signals (in bold). The reading frames of the
splice variants are indicated show restored or shifted frames.
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Abolition of differential splicing restores endogenous presentation
and recognition of a viral CTL epitope
A logical prediction of the data was that removal of the 5'-splice
site would abolish differential splicing of the RK-BARF0 transcript and
result in increased cDNA encoding the LLWAARPRL epitope. To test this
hypothesis, an EBV-negative, HLA-A2-positive BL cell line (DG75) was
stably transfected with plasmids pE-BARF0 (expressing the BARF0 ORF
without the 5'-splice site), pE-F-RKBARF0, or a control vector (Fig. 3
A). RT-PCR analysis of RNA
from these transfectants using primers BARF0-F and BARF-2R showed
strong differential splicing in the cell line containing plasmid
pE-F-RKBARF0 (Fig. 3
B, lane 3). In contrast,
RT-PCR analysis using a primer combination flanking the LLWAARPRL
epitope (LLW-F and BARF2-R) revealed a single 227-bp cDNA product in
BARF0-expressing cells (DG75(E-BARF0) and DG75(E-F-RKBARF0)) but not
from the control cells (Fig. 3
B). Densitometric analysis
(standardized to a 131- or 498-bp cDNA fragment of the housekeeping
gene ß2-microglobulin or ß-actin,
respectively) indicated that cells transfected with the
splice-deficient BARF0 construct expressed
4-fold more LLWAARPRL
epitope-encoding mRNA than cells expressing full length RK-BARF0.

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FIGURE 3. Removal of the 5' splice site abolishes differential splicing and
restores recognition of the RK-BARF0 CTL epitope. A,
Schematic diagram of the plasmids pE-BARF0 and pE-F-RKBARF0 with the
SV40 promotor ( ) driving transcription of the BARF0 ORF or
N-terminally Flag-tagged RK-BARF0. The Flag epitope (shown as a flag)
and the differential splice sites are illustrated. The numbering (in
base pairs) starts at the RK-BARF0 reading frame. For detailed plasmid
description, see legends of Figs. 1 A and
2A. B, RT-PCR. EBV-negative DG75 BL cell
lines were generated that stably expressed a control vector (DG75(E))
(1), plasmid pE-BARF0 (DG75(E-BARF0)) (2), or pE-F-RKBARF0
(DG75(E-F-RKBARF0)) (3). The total RNA of these cells was analyzed by
RT-PCR as outlined in Fig. 2 A. The four primer
combinations used for PCR amplification are indicated in bold (BARF0-F
+ BARF2-R, LLW-F + BARF2-R, ß2-microglobulin
(ß2-M), ß-actin), and the arrowheads show the positions
of the spliced (F-S#13) and unspliced cDNA products. Amplification of
the housekeeping ß2-microglobulin and ß-actin cDNAs
served as an internal controls for the densitometric analysis. Cloning
and sequencing of the cDNA products confirmed that the same splice
sites as seen in the EBV-infected cells (Fig. 2 B) were
used. C, 51Cr release assay using
RK-BARF0-specific CTL clone C1. EBV-negative DG75 BL cells
and EBV-positive NK LCLs stably transfected with either a
control vector (DG75(E), NK(E)) or plasmids pE-F-RKBARF0
(DG75(E-F-RKBARF0), NK(E-F-RKBARF0)), or pE-BARF0 (DG75(E-BARF0),
NK(E-BARF0)), respectively, were used as targets at different E:T
ratios.
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To test whether these mRNA levels corresponded to an increase in
endogenous presentation, these DG75 transfectants were analyzed for
CTL-mediated killing using the RK-BARF0-specific CTL clone C1 (Fig. 3
C). Only the DG75(E-BARF0) transfectants expressing the
splice-deficient BARF0 transcript were susceptible to lysis, whereas
cells transfected with pE-F-RKBARF0 or the vector control were not
recognized. Similarly, only the EBV-positive NK LCL stably expressing
the splice-deficient BARF0 transcript (NK(E-BARF0)), but not the
transfectants NK(E-F-RKBARF0) and NK(E), were killed by the
RK-BARF0-specific CTL clone (Fig. 3
C).
The immunoblot analysis of the DG75(E-F-RKBARF0) and NK(E-F-RKBARF0)
transfectants using an anti-Flag mAb revealed that the majority of
the Flag-tagged proteins were 1620 kDa in mass which correlated with
the predicted molecular mass of the spliced cDNA variants lacking the
LLWAARPRL epitope. In contrast, the full length RK-BARF0 (32kDa)
protein was
9 fold lower expressed as indicated by densitometric
analysis (Fig. 1
C and data not shown). Although the level of
full length RK-BARF0 was below the threshold of T cell recognition, it
was apparently sufficient to induce and maintain a specific CTL
response in seropositive but not seronegative individuals (5).
Expression of endogenous RK-BARF0 protein in the EBV-positive NK LCL
transfectants was difficult to monitor as the polyclonal rabbit
anti-RKBARF0 serum previously reported (10) showed
cross-reactivity with cellular B cell proteins which were of a mass
similar to that of the 32-kDa RK-BARF0 protein (our manuscript in
preparation). Taken together, these results clearly demonstrated that
differential splicing directly influences endogenous presentation of
this viral CTL epitope in both transfected and EBV-infected target
cells and that deletion of the unique 5'-splice site restores CTL
killing.
In EBV-positive BL and NPC cells, there are different splice variants
of the BamHI A transcript that share the BARF0 ORF at their
3'-terminal ends, giving rise to many different predicted protein
products (3, 4). Our data in Fig. 2
showed that the BARF0 ORF was
differently spliced in LCLs, BL, and NPC cells established with five
virus isolates, indicating an evolutionary conservation of this
splicing pattern. Thus, it seems that EBV takes advantage of a common
cellular mechanism of gene regulation, differential splicing, which
excises immunogenic fragments from the BamHI A protein
products, thereby silencing T cell determinants. Recent reports from
melanoma research have demonstrated that malignant cells, but not their
normal counterparts, can express functional CTL epitopes (that are
normally hidden within introns) which render them susceptible to
melanoma-specific CTLs (11, 12).Although in this case differential
splicing created new CTL epitopes, our data demonstrate a contrary
function that results in silencing of a functional CTL epitope. Thus,
differential splicing, as seen in many viruses and parasites, may not
only have a role in regulating gene expression and generating protein
isoforms but also contribute to immune evasion of pathogens and
malignancies. Given the universal usage of differential splicing in
eukaryotes, it is also likely that this process could be extended to
the discrimination of self and nonself Ag and contribute to
autoimmunity.
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Acknowledgments
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We thank the members of the EBV Unit at Queensland Institute of
Medical Research, particularly for technical help provided by M.
Buck, S. Cross, and L. Morrison; the critical manuscript
reading of D. Moss; and P. Busson and N. Raab-Traub for
providing cells and plasmids.
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Footnotes
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1 This work was supported by grants from the National Health and Medical Research Council, the Queensland Cancer Fund, and the University of Queensland, Australia. R.K. is supported by an R. D. Wright Fellowship from the National Health and Medical Research Council. 
2 Address correspondence and reprint requests to Dr. Norbert Kienzle, Queensland Institute of Medical Research, Post Office, Royal Brisbane Hospital Qld 4029, Australia. E-mail address: 
3 Abbreviations used in this paper: BL, Burkitts lymphoma; NPC, nasopharyngeal carcinoma; LCL, lymphoblastoid cell line; ORF, open reading frame. 
Received for publication February 17, 1999.
Accepted for publication April 19, 1999.
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References
|
|---|
-
Powis, S. H.. 1998. Lessons from an age-old war. Nat. Med. 4:887.[Medline]
-
Rickinson, A. B., D. J. Moss. 1997. Human cytotoxic T lymphocyte responses to Epstein-Barr virus infection. Annu. Rev. Immunol. 15:405.[Medline]
-
Sadler, R. H., N. Raab-Traub. 1995. Structural analyses of the Epstein-Barr virus BamHI A transcripts. J. Virol. 69:1132.[Abstract]
-
Hitt, M. M., M. J. Allday, T. Hara, L. Karran, M. D. Jones, P. Busson, T. Tursz, I. Ernberg, B. E. Griffin. 1989. EBV gene expression in an NPC-related tumour. EMBO J. 8:2639.[Medline]
-
Kienzle, N., T. B. Sculley, L. Poulsen, M. Buck, S. Cross, N. Raab-Traub, R. Khanna. 1998. Identification of a cytotoxic T-lymphocyte response to the novel BARF0 protein of Epstein-Barr virus: a critical role for antigen expression. J. Virol. 72:6614.[Abstract/Free Full Text]
-
Pope, J. H.. 1968. Establishment of cell lines from Australian leukaemic patients: presence of a herpes-like virus. Aust. J. Exp. Biol. Med. Sci. 46:643.[Medline]
-
Baer, R., A. T. Bankier, M. D. Biggin, P. L. Deininger, P. J. Farrell, T. J. Gibson, G. Hatfull, G. S. Hudson, S. C. Satchwell, C. Seguin, P. S. Tuffnell, B. G. Barrell. 1984. DNA sequence and expression of the B95-8 Epstein-Barr virus genome. Nature 310:207.[Medline]
-
Kienzle, N., D. B. Young, D. Liaskou, M. Buck, S. Greco, T. B. Sculley. 1999. Intron retention may regulate expression of Epstein-Barr virus nuclear antigen 3 family genes. J. Virol. 73:1195.[Abstract/Free Full Text]
-
Moss, D. J., I. S. Misko, S. R. Burrows, K. Burman, R. McCarthy, T. B. Sculley. 1988. Cytotoxic T-cell clones discriminate between A- and B-type Epstein-Barr virus transformants. Nature 331:719.[Medline]
-
Fries, K. L., T. B. Sculley, J. Webster-Cyriaque, P. Rajadurai, R. H. Sadler, N. Raab-Traub. 1997. Identification of a novel protein encoded by the BamHI A region of the Epstein-Barr virus. J. Virol. 71:2765.[Abstract]
-
Guilloux, Y., S. Lucas, V. G. Brichard, A. Van Pel, C. Viret, E. De Plaen, F. Brasseur, B. Lethe, F. Jotereau, T. Boon. 1996. A peptide recognized by human cytolytic T lymphocytes on HLA-A2 melanomas is encoded by an intron sequence of the N- acetylglucosaminyltransferase V gene. J. Exp. Med. 183:1173.[Abstract/Free Full Text]
-
Lupetti, R., P. Pisarra, A. Verrecchia, C. Farina, G. Nicolini, A. Anichini, C. Bordignon, M. Sensi, G. Parmiani, C. Traversari. 1998. Translation of a retained intron in tyrosinase-related protein (TRP) 2 mRNA generates a new cytotoxic T lymphocyte (CTL)-defined and shared human melanoma antigen not expressed in normal cells of the melanocytic lineage. J. Exp. Med. 188:1005.[Abstract/Free Full Text]
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