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J Virol, May 1998, p. 3547-3553, Vol. 72, No. 5
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Cross-Reactions between the Cytotoxic T-Lymphocyte Responses of
Human Immunodeficiency Virus-Infected African and European
Patients
Deniz
Durali,1
Jacques
Morvan,2
Franck
Letourneur,3
Doris
Schmitt,4
Nelly
Guegan,1
Marc
Dalod,1
Sentob
Saragosti,3
Didier
Sicard,5
Jean-Paul
Levy,3 and
Elisabeth
Gomard1,*
Laboratoire d'Immunologie des Pathologies
Infectieuses et Tumorales, Unité INSERM 445, Université
René Descartes,1
Institut Cochin
de Génétique Moléculaire,3 and
Département de Médecine
Interne,5 Hôpital Cochin, Paris, and
Transgène, Strasbourg,4 France,
and
Institut Pasteur, Bangui, Central African
Republic2
Received 15 September 1997/Accepted 12 January 1998
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ABSTRACT |
The great variability of protein sequences from human
immunodeficiency virus (HIV) type 1 (HIV-1) isolates represents a major obstacle to the development of an effective vaccine against this virus.
The surface protein (Env), which is the predominant target of
neutralizing antibodies, is particularly variable. Here we examine the
impact of variability among different HIV-1 subtypes (clades) on
cytotoxic T-lymphocyte (CTL) activities, the other major component of
the antiviral immune response. CTLs are produced not only against Env
but also against other structural proteins, as well as some regulatory
proteins. The genetic subtypes of HIV-1 were determined for Env and Gag
from several patients infected either in France or in Africa. The
cross-reactivities of the CTLs were tested with target cells expressing
selected proteins from HIV-1 isolates of clade A or B or from HIV type
2 isolates. All African patients were infected with viruses belonging
to clade A for Env and for Gag, except for one patient who was infected with a clade A Env-clade G Gag recombinant virus. All patients infected
in France were infected with clade B viruses. The CTL responses
obtained from all the African and all the French individuals tested
showed frequent cross-reactions with proteins of the heterologous clade. Epitopes conserved between the viruses of clades A and B
appeared especially frequent in Gag p24, Gag p18, integrase, and the
central region of Nef. Cross-reactivity also existed among Gag
epitopes of clades A, B, and G, as shown by the results for the
patient infected with the clade A Env-clade G Gag recombinant virus.
These results show that CTLs raised against viral antigens from
different clades are able to cross-react, emphasizing the possibility
of obtaining cross-immunizations for this part of the immune response
in vaccinated individuals.
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INTRODUCTION |
Genetic variability is one of the
most remarkable hallmarks of human immunodeficiency virus (HIV), and it
represents a major obstacle to the design of a vaccine against this
virus. Due to this characteristic, neutralizing antibodies which are
predominantly directed against the V3 loop of the envelope protein
(gp120) react with only a small number of virus isolates (2, 27,
34). Other antibodies, especially those directed against
conformational epitopes of the CD4 ligand of gp120 or transmembrane
protein gp41, can neutralize a wider range of HIV type 1 (HIV-1)
isolates (reviewed in reference 9). However, these
antibodies are rarely, if ever, induced by vaccination. Cytotoxic T
lymphocytes (CTLs) are thought to be another important component of the
antiviral immune response. Indeed, the capacity of HIV-specific CTLs to
efficiently limit viral replication is suggested by a large decrease in
HIV load following the initial appearance of CTLs during primary
infection (reviewed in reference 32) and by the
temporal association between high CTL activity and stable viral load or
CD4+ cell counts during asymptomatic stages (16, 28,
29). Furthermore, HIV-exposed but seronegative individuals, as
well as uninfected children born to HIV-1-infected mothers, have
exhibited anti-HIV CD8+ CTL reactivity as a unique sign of
virus exposure (6, 31). Thus, it is generally accepted that
vaccination must induce CTLs as well as neutralizing antibodies, so
that infected cells can be killed before they produce any virus.
There are many target epitopes of CTLs, depending on donor HLA
specificities; about 90 epitopes have been identified on the various structural and regulatory proteins of the virus (4, 13-15, 17, 18, 35, 36, 38, 41, 42; reviewed in reference 3). However, most experiments have involved
lymphocytes from European or American donors infected with viruses of
clade B. CTL activity has been reported for HIV type 2 (HIV-2)-infected patients (1, 12, 26, 31), but to our knowledge only one study has concerned African people infected with African HIV-1 isolates
(31). We studied lymphoid cells from the blood of clade A
virus-infected African patients and/or clade B virus-infected French
patients. Both were tested against autologous target cells infected
with recombinant viruses expressing various proteins from clade A or B
viruses or from HIV-2. The large degree of cross-reactivities observed
suggests that the variability of viral proteins will not be an obstacle
in obtaining cross-reacting CTL in vaccinated individuals.
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MATERIALS AND METHODS |
Subjects.
Heparinized blood samples were collected from 16 consenting HIV-1-seropositive individuals, 7 in Bangui (Central African
Republic) and 9 in France (1 was originally from Togo; patient W121).
They were first diagnosed as HIV positive between 1989 and 1995. All had circulating anti-HIV-1 antibodies but not anti-HIV-2 antibodies. Peripheral blood mononuclear cells (PBMC) were isolated by density gradient centrifugation and frozen. HLA-A, -B, and -C types were determined serologically by the Laboratory of Immunology and
Histocompatibility at Hospital Saint-Louis, Paris, France: B12
(HLA-A3/32, B41/
, C3/6); B15 (HLA-A3/31, B7/52, C6/); B16
(HLA-A23/24, B13/47, C2/); B18 (HLA-A2/31, B13/55, C2/6); B20
(HLA-A2/30, B7/13, C3/); B22 (HLA-A2/30, B27/44, C2/); B23
(HLA-A19.2/, B44/57, C6/); and W121 (HLA-A2/33, B50/70, C2/6).
Genetic subtyping of HIV-1 strains.
The genetic subtypes of
HIV-1 were determined by a heteroduplex mobility assay (8).
The C2V5 region of the env gene was amplified by nested PCR
with the ED5 and ED12 primers for the first round and the ES8 primers
for the second round. The gag gene was amplified by nested
PCR with the G00 and G01 primers for the first round and the G60 and
G25 primers for the nested PCR (33). The amplified fragment
was then purified with a PCR product purification kit (33)
and sequenced with a p24-specific internal primer by using dye
terminator chemistry (Perkin-Elmer) on an automated DNA sequencer
(Applied Biosystems 373A). DNA sequences were analyzed with the
multiple sequence analysis program CLUSTALW (37). Reference
strains for each subtype for the region analyzed were included in this
study. Tree topology based on 634 nucleotides was inferred by the
neighbor-joining method.
Vaccinia viruses.
The viruses used to infect target cells
were vaccinia viruses (Copenhagen strain) recombined with the complete
env, gag, pol, or nef gene
of HIV-1 (LAI strain) (resulting in viruses Env/LAI, Gag/LAI, Pol/LAI,
and Nef/LAI). Recombinant viruses encoding various proteins, such as
gp120, gp41, p24, p18, reverse transcriptase (RT), integrase, or
protease, were also used. They were produced as previously described
(20, 21). An initiation codon, a stop codon, and adequate
restriction sites were introduced during the construction of the Nef-1
(codons 1 to 72), Nef-2 (codons 73 to 147), and Nef-3 (codons 145 to
206) regions of Nef by local mutagenesis immediately before and after
the indicated positions. Other recombinant vaccinia viruses were also
constructed to express genes from isolates of subtype A of HIV-1 or of
HIV-2. Gag/CAR, Pol/CAR, and Nef/CAR vaccinia viruses expressed the
corresponding genes from HIV-1 92CAR3253 (obtained from a Central
African Republic patient). The corresponding DNA fragments were
amplified by PCR from DNA extracted from human PBMC infected with this
isolate (obtained from F. Barré-Sinoussi). Adequate restriction
sites were introduced during the amplification procedure. Pol/CAR
expressed the complete pol gene. The Gag protein produced by
Gag/CAR lacked 36 amino acids at the C terminus and ended with PPAEI.
The Nef protein produced by Nef/CAR lacked 3 amino acids at the C
terminus and ended with MKPEF. Env/OUG vaccinia virus expressed the
native envelope protein gene of HIV-1 92UG037 (from a Ugandan patient). Env/ROD, Gag/ROD, and Nef/ROD vaccinia viruses expressed the
corresponding genes from HIV-2 (ROD strain) (obtained from a West
African patient). These genes were excised from the genome of
HIV-2ROD and subjected to local mutagenesis to introduce
restriction sites before the ATG initiation codon and after the stop
codon. They were then introduced into the genome of the vaccinia virus.
The stop codon in the gp36 coding sequence was removed by local
mutagenesis to restore the reading frame of the native envelope protein
gene.
Peptides.
Peptides corresponding to epitopes previously
identified in clade B viral sequences (23) were synthetized
by Neosystem (Strasbourg, France): Gag 77-85 (SLYNTVATL)
(39), Gag 263-272 (KRWIILGNK) (25), Nef 73-82 (QVPLRPMTYK) (19), and Nef 136-145 (PLTFGWCFKL) (15). They were supplied by the Agence Nationale de
Recherche sur le SIDA. Lyophilized peptides were dissolved in water (2 mg/ml) and stored at 20°C.
Generation of anti-HIV cell lines.
Polyclonal anti-HIV cell
lines were obtained by culturing PBMC (106/ml) with
autologous phytohemagglutin-activated lymphocytes (2 × 105/ml) as described previously (20). The cells
were incubated for 3 days in RPMI 1640 (GIBCO) supplemented with 2 mM
L-glutamine, 10 mM HEPES buffer, and 10% fetal calf serum.
They were then cultured at a concentration of 106/ml in
medium supplemented with 10 U of human recombinant interleukin 2 (Boehringer) per ml. Cytolytic activity was tested after 14 to 21 days
in culture.
Antipeptide cell lines were generated in some experiments by use of the
same culture medium as that described above and by coculturing
107 PBMC (4 × 106/ml) with a similar
number of autologous PBMC which had been treated with a pulse of 1 µg
of peptide for 90 min and irradiated. Continuous cell lines were
established by similar weekly stimulation as previously described
(7).
CRT.
The target cells used in the chromium release test
(CRT) were autologous lymphoblastoid cells obtained by transforming
PBMC with Epstein-Barr virus (EBV-LCL). They were infected with
recombinant vaccinia viruses by incubation with 5 PFU per cell for
18 h. Wild-type vaccinia virus (Vac/WT) was used as a control.
EBV-LCL were labeled by incubation with 100 µCi of
Na251CrO4 (Amersham) for 1 h
and washed twice. EBV-LCL incubated with 1 µg of peptide for 90 min and then extensively washed were used as target cells in some
experiments. The control consisted of target cells incubated with
medium alone.
The CRT was performed with microculture plates by incubating various
concentrations of effector cells and 5 × 103 target
cells in RPMI 1640 supplemented with 10% fetal calf serum for 4 h. The supernatants were then harvested, and the chromium released was
measured in a gamma counter. The spontaneous release was 10 to 25% of
the total Cr incorporated. The specific chromium release was calculated
as 100 × [(experimental spontaneous release)/(total Cr
incorporated spontaneous release)]. HIV-specific activity was
considered to be present when the specific chromium release was 10%
greater than that of the control Vac/WT for two different effector/target cell ratios. Lytic units (LU) were calculated for
108 effector cells as 108/(5,000 × E/T30%), where E/T30% is the effector/target
cell ratio that yields 30% specific lysis of 5,000 target cells. LU
for Vac/WT were always less than 3.
Nucleotide sequence accession numbers.
The nucleotide
sequences of the HIV-1 gag p24 region for patients B12, B15,
B16, B18, B20, B22, B24, and W121 were deposited in the EMBL Nucleotide
Sequence Database under accession no. Y16612 to Y16619, respectively.
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RESULTS |
Genetic subtyping of HIV-1 strains.
The samples from the
Caucasian patients all formed fast-migrating heteroduplexes with the
subtype B reference strain. The viruses originating from Bangui (B12,
B15, B16, B18, B20, B22, and B23) all clearly formed fast-migrating
heteroduplexes with the subtype A reference strain, as did the viral
isolate from the patient from Togo (W121). Many different genetic
subtypes have been found in the Central African Republic (24,
33a): A, E, D, C, H, G, and U (decreasing order of frequency); it
is possible that some of the isolates studied were indeed recombinant genomes (11, 30). However, as no subtype B was found in this country, it is unlikely that any of the Bangui isolates were A-B recombinants. We sequenced part of the Gag region for Bangui isolates and for the virus from Togo. Seven of the eight viruses were identified as belonging to clade A (Fig. 1). One
virus (B15) clustered with the subtype G isolates, showing that this
virus was an A-G recombinant.
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FIG. 1.
Phylogenetic analysis of gag nucleotide
sequences. The phylogenetic tree was generated by the neighbor-joining
method and drawn with Njplot. The numbers given at the branch points
are the 50% threshold majority consensus values for 100 bootstrap
replicates. The lengths of the horizontal branches are proportional to
the relative evolutionary distances; vertical distances are for clarity
only. The strains isolated from the African patients described in this
study, as well as the strain used to produce the recombinant vaccinia
viruses encoding the gag gene (92CAR3252), are shown in bold
type.
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Reactivity of CTLs stimulated with endogenous virus.
Lymphoid
cells from the 16 patients were stimulated in vitro with autologous
phytohemagglutinin-activated blast cells, so that the restimulating
viral proteins were from endogenous viruses from the same patient. CTL
reactivities were tested against a panel of structural proteins (Env,
Gag, or Pol) from clade A or B viruses and against Nef (from clade A
and B viruses), as Nef is the most frequently recognized regulatory
protein (20). Reactivities with the Env, Gag, and Nef
proteins of HIV-2ROD were also tested. The reagent for
testing HIV-2 Pol was not available.
The results found with CTLs from clade A virus-infected patients are
summarized in Table
1, and an example is
shown in Fig.
2A. The CTLs from these
eight patients clearly reacted with several
clade A proteins; CTLs from
three of them reacted with all four
proteins tested, CTLs from three
reacted with three proteins,
and CTLs from two reacted with two
proteins. Pol epitopes were
recognized by CTLs from all donors, Gag
and Nef epitopes were
recognized by CTLs from most of them (seven
of eight), but Env-reacting
CTLs were found in only three of the eight
donors. Figure
2A shows
that B18-derived CTLs recognized equally well
the Gag epitopes
of CAR (clade A), LAI (clade B), and even ROD
(HIV-2) viruses.
Clear cross-reactivities were also found with Env,
Pol, and Nef;
in all cases, the levels of the responses were equivalent
for
CAR or LAI viruses. In contrast, cross-reactivities against ROD
(HIV-2) were found only for Gag. CTLs from the other seven African
patients also showed multiple cross-reactions with proteins of
clade B
viruses. The levels of their responses to Gag proteins
of the two
subtypes were similar. The reactivity with Pol was
stronger with the
homologous protein. Nevertheless, CTLs from
all but one donor reacted
with Pol/LAI. Finally, five of the seven
donors had CTLs that
recognized Nef/CAR and Nef/LAI in the same
response range. In contrast,
cross-reactivity with the Env protein
was weaker; only one of the three
donors (B18) whose CTLs reacted
with Env/CAR had CTLs that also reacted
with Env/LAI, but with
weaker activity. CTLs from clade A-infected
donors seldom cross-reacted
with HIV-2 proteins. No cross-reactivity
was found with Env or
Nef, and reactivities against Gag/ROD were
observed with CTLs
from only three donors among the eight whose CTLs
were capable
of recognizing Gag/CAR.
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FIG. 2.
CTL activities in patients carrying viruses B18
(infected with clade A HIV-1) (A) and CO3M (infected with clade B
HIV-1) (B). Effector cells were tested after in vitro restimulation
with autologous blast cells. Target cells were infected with
recombinant vaccinia viruses expressing the Env, Gag, Pol, or Nef
protein of clade A and B isolates.
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Similar experiments with lymphoid cells from clade B-infected European
patients yielded similar results (Table
2). CTLs from
all eight donors reacted
with several proteins from clade B viruses,
consistent with previous
work (
20). Figure
2B shows the strong
cross-reactivities of
CTLs from the donor carrying virus CO3M
with Env, Gag, and Nef proteins
of clades A and B. Altogether,
the CTLs of most clade B-infected
patients (seven of eight) reacted
with Nef/CAR (clade A), and the
response was in the same range
as that for Nef/LAI. Cross-reactivities
against Env/OUG (four
of eight), Gag/CAR (five of eight), and Pol/CAR
(six of eight)
were also found. Finally, no CTLs from any of the clade
B-infected
patients were found to react with target cells expressing
ROD
(HIV-2) Env, Gag, or Nef.
Cross-reactivities of CTLs with various Env, Gag, Pol, and Nef
subregions.
It is important for vaccine development to further
determine the precise targets of cross-reacting CTLs. To do this, we
used target cells infected with recombinant vaccinia viruses expressing Env gp120, Env gp41, Gag p24, Gag p18 (the recombinant for Gag p15 was
not available), RT, integrase, or protease. Three recombinants expressing the N-terminal (Nef-1), central (Nef-2), or C-terminal (Nef-3) regions of Nef were also tested. All were from the clade B LAI
isolate, the corresponding clade A reagents not being available. Previous experiments largely documented the capability of CTLs from
patients infected with clade B viruses to react against these different
proteins (reviewed in reference 40). This
characteristic was tested with CTLs from African patients (Table
3). Reactivity against Env was rare,
found in only one of the seven donors (B18), who produced CTLs specific
for both gp120 and gp41 of the LAI isolate. On the contrary, broad
cross-reactivities were detected with Pol and Gag, as p24 and p18 from
the LAI isolate were recognized by CTLs from four of the six clade
A-infected donors; RT was recognized by CTLs from two of the seven,
protease was recognized by CTLs from only one of the seven, and
remarkably enough integrase was recognized by CTLs from all seven of
the African donors (at least four of them had a strong response).
Finally, the reactivities detected against Nef in five of the seven
patients always revealed cross-reacting epitopes in the central
region of this protein.
Identification of conserved epitopes.
We
investigated the presence in African patients of CTLs
specific for peptides previously identified as epitopes in clade B
viruses. This was feasible, since all of these donors had at least one
class I molecule corresponding to a known epitope already studied
in European or American patients. When PBMC were still available,
antipeptide cell lines were produced, and CTL activity was tested
against target cells sensitized with the corresponding peptide or
infected with recombinant vaccinia virus. It is important to note
that this experimental approach allows the detection of CTLs from PBMC
of only infected (or vaccinated) individuals.
CTLs from patient B18 recognized epitopes Gag 77-85 (
39)
and Nef 136-145 (
15), which are known to be HLA-A2
restricted
(Fig.
3a and b). These CTLs also lysed target
cells infected with
recombinant vaccinia viruses carrying the
corresponding genes
from the LAI and CAR isolates but not the
HIV-2
ROD isolate. Similarly,
epitope Nef 73-82, which is restricted to HLA-A3 (
19), was recognized
by CTLs
from patient B12 (Fig.
3c). Finally, CTLs from patient
B22 reacted with
the well-known HLA-B27-restricted epitope Gag
263-272 (
25) (Fig.
3d) but not with the HLA-A2-restricted
epitope
Nef 136-145.
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FIG. 3.
Recognition of known epitopes by CTLs from African
patients. CTLs were produced by in vitro stimulation with synthetic
peptides. They were tested against target cells previously treated with
the corresponding peptide or infected with recombinant vaccinia virus
(Vac) (except for the B12 cell line, because effector cells were not
available). The HLA typing was as follows: for B12, HLA-A3/32, B41/,
C3/6; for B22, HLA-A2/30, B27/44, C2/; and for B18, HLA-A2/31,
B13/55, C2/6. The target cells were heterologous EBV-LCL sharing HLA-A3
with B12 CTLs, HLA-B27 with B22 CTLs, or HLA-A2 with B18 CTLs.
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| |
DISCUSSION |
Anti-HIV-1 CTL responses have been studied almost exclusively in
Europe and North America with lymphoid cells from people infected with
clade B viruses. They are directed against several proteins of the same
virus and often against several epitopes of the same protein. This
polymorphism of CTL responses is well documented for these viruses
(reviewed in reference 40). Our results show that
the same polymorphism exists for anti-clade A virus CTL responses
(Table 1). CTLs from all eight patients tested responded to several
structural proteins and also frequently to Nef, with at least three to
five different CTL activities in the same donor (Table 3). It is
interesting to note, however, that Env was recognized by the CTLs from
only three of the eight patients, suggesting a low prevalence of
broadly cross-reactive Env-specific CTLs among clade A virus-infected
individuals, consistent with results reported for clade B viruses
(5). Moreover, this study clearly demonstrates frequent
cross-reactivities in the CTL responses obtained after infection with
viruses belonging to two different clades. Several patients had almost
identical CTL reactions to Gag and Nef proteins from clade A and B
viruses, regardless of whether the original virus was of clade A or B. The homologous proteins sometimes elicited a stronger response, notably
with Pol targets, but even in this case cross-reactivity was evident.
Weaker cross-reactivities were detected against Env proteins. The CTLs
of African patients were selective for homologous clade A Env. CTLs
from only one donor showed a cross-reaction with Env/LAI. In the
reverse situation, CTLs from four of the eight European donors
cross-reacted with clade A Env. It is not surprising that Gag, Pol, and
Nef were better targets for cross-reaction than Env, since the
variability of Env is especially important and well known.
It must be emphasized that the classical methods used to test CTLs
allow demonstration only of responses directed to conserved epitopes, as patients are stimulated with epitopes of their own viruses, which are variable, while the tests are carried out with target cells infected with a single recombinant vaccinia virus. The
target cells for clade B viruses generally express viral proteins from
HIV-1LAI, so only epitopes conserved between LAI and
the infecting virus can be revealed in the reaction. Similarly, the recently produced panel of recombinants expressing different clade A
proteins was produced with a single clade A virus, so only epitopes conserved among clade A virus-infected donors can be detected. The same
epitopes are probably responsible for most of the cross-reactivity between the two clades, as few differences were detected in
cross-reactions involving Gag, Pol, or Nef. The target epitopes map
to Gag p18 and p24 and the central region of Nef, as has already been
shown for clade B viruses (3). Our results suggest a
particular importance for integrase epitopes with constant
cross-reactivities between clade A and B viruses (Table 3). Reactions
directed against integrase are poorly documented. However, we
previously identified this enzyme as a good CTL target for clade B
viruses (21). Cross-reactivities with HIV-2 are only
occasional. We found that anti-clade A virus CTLs sometimes
cross-reacted with HIV-2 Gag protein, as previously reported (12,
26, 31), whereas they did not cross-react with other proteins. On
the other hand, CTLs from patients infected with clade B viruses did
not cross-react with HIV-2 proteins.
It is very probable that only some of the epitopes recognized on
homologous proteins are responsible for cross-reactivity. However, our
results suggest that obstacles to vaccination because of the induction
of broadly cross-reactive neutralizing antibodies seem not to affect
CTL responses so extensively. This idea is not surprising because the
target proteins of CTLs are less variable than the V3 loop and because
the African patients tested shared with northern populations at least
one HLA specificity capable of presenting previously identified
epitopes, although we did not select for this. Further studies are
required to investigate cross-reactivities with viruses of other
clades, including C, D, E, and G, and even viruses of type 0. It is
likely that strong cross-reactivities will be found, as one of the
donors bore a virus (B15) belonging to clade G (for the Gag proteins)
but reacting with clade A and B Gag proteins, including p24 and p18.
Viruses of clade E also carry a clade A gag gene
(11), so cross-reactions probably will be identified at
least against Gag.
Results obtained with synthetic epitopes showed that African
patients have CTL precursors which react with previously identified epitopes in Gag and Nef proteins of clade B isolates. Similar experiments performed with European patients allowed us to discover such cross-reactivities at the epitope level (data not shown). For
example, CTLs specific for the Nef 84-92 epitope (7)
were able to recognize target cells infected with Vac/CAR. This result is not surprising, since the peptide sequence is conserved between LAI
and CAR isolates. A similar finding was obtained for the RT 325-333 epitope (41), suggesting that the mutation Ser (LAI isolate) 
Ala (CAR isolate) at position 8 did not affect the epitope. Similarly, mutations observed in CAR isolates at the level
of the Nef 73-82, Gag 77-85, and Gag 263-272 epitopes did not
induce escape of recognition by CTLs from African patients (Fig. 3).
These results are consistent with previous reports of conserved
epitopes shown with CTLs from patients infected with clade B
isolates (reviewed in reference 22) or from
uninfected vaccinated volunteers (10). They show that
cross-reactivity can be due to conservation of epitope sequences as
well as to cross-recognition of epitopes which differ in amino acid
sequences. However, further studies are necessary to identify the
precise epitopes involved in cross-reactions. This identification
may be of value in developing a vaccination system based on peptides or
lipopeptides, although the level of CTL response required for possible
in vivo protection is not known.
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ACKNOWLEDGMENTS |
This work was supported by grants from the Agence Nationale de
Recherche sur le Sida (ANRS) and Ensemble Contre le SIDA, Sidaction, Paris, France. Deniz Durali was supported by a fellowship from ANRS.
We thank Jean-Gérard Guillet for support; Françoise
Barré-Sinoussi and Marie-Paule Kiény for providing the
HIV-1 92CAR3253 isolate and the recombinant vaccinia viruses; and
Jean-Christophe Deschemin, Julienne Ipero, Josiane Leal, and Karine
Dott for excellent technical assistance. We also acknowledge the
generous participation of the patients involved in these studies. The
English text was edited by Julie Knight.
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FOOTNOTES |
*
Corresponding author. Mailing address: INSERM U445,
ICGM, Hôpital Cochin, 27 rue du Faubourg Saint-Jacques, 75674 Paris Cedex 14, France. Phone: (33) 1 46 33 02 92. Fax: (33) 1 44 07 14 25. E-mail: u445-guillet{at}cochin.inserm.fr.
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Top
Abstract
Introduction
