Bridging the Gap: Conference Record [Abstract book, International Conference on AIDS (12th: 1998: Geneva, Switzerland)]

30 Abstracts 11239-11242

12th World AIDS Conference

added in the remaining coding region. All animals received an intravenous
inoculation of 103 TCID (n = 20/isolate). After 85 weeks, 15 animals per isolate (n = 5/group) were challenged with SIVmac239, SlVsmPBj6.6, SIVsmE660, or
SHIV89.6PD.
Results: Ten of 20 SIVmac239Anef immunized animals and 18 of 20 SlVsmPBj6.6Anef
immunized animals controlled the virus by 20 weeks of immunization. The remaining animals were culture positive at most or all time points, with some
maintaining detectible circulating viral RNA. Three of five animals immunized
with SIVmac239Anef and challenge with SIVmac239 were protected from persistent
infection. All of the SIVmac239Anef immunized, SIVsmE660 or SHIV89.6PD challenged
animals developed infections with the challenge isolate. No acute pathologic
events were observed in the vaccinates following SIVsmE660 or SHIV89.6PD challenges. Plasma viral levels were 1-4 logio lower in infected, vaccinated animals
when compared to controls. The animals infected with SIVmac239Anef that were unable to control its replication were more susceptible to the challenge viruses and
disease progression. Animals immunized with SIVsmpBj6.6Anef were challenged
with SIVmspBj6.6, SIVmac239 or SHIV89.6PD. Vaccinates were uniformly protected
from infection with homologous SIVsmPBj6.6. Three of five animals were protected
from the SIVmac239 challenge and virus was isolated at only early time points in
the remaining two. Two of the five vaccinates were protected against SHIV89.6PD,
with intermittent isolation from the remaining vaccinates. Control animals were
persistently infected. No acute pathologic events were observed in the infected
vaccinates, with viral levels reduced 3 to 4 logio.
Conclusions: Attenuated SIV vaccines were shown to effectively protect
against homologous virus challenge. Protection against heterologous challenge
was less effective. Acute pathologic events were eliminated or reduced in all vaccinates. Vaccinates unable to contain the attenuated virus during the vaccination
period, were not protected from infection by the virulent challenge and progressed
to disease more rapidly then the controls.
547*/711239 Role of 3-chemokines in protective immunity
against intrarectal SIVsm challenge of macaques
Rigmor Thorstensson1, R. Ahmed1, C. Wilson1, P. Putkonen1, Y. Wang2,
T. Lehner2, G. Biberfeld'. 'Swedish Institute For Infectious Disease Control,
10521 Stockholm, Sweden; 2Guys Hospital, London, UK
Background: Simian immunodeficiency virus (SIV) uses chemokine receptor 5
(CCR 5) as the main coreceptor to enter CD4+ cells. The P-chemokines RANTES,
MIP-la and MIP-1 / are ligands for CCR 5. The aim of this study was to investigate
the CD8+ T-cell production of /-chemokines in macaques vaccinated with live
attenuated vaccines in relation to protection against infectious intrarectal (ir) SIV
challenge.
Methods: Six cynomolgus macaques (groupA) were inoculated with an attenuated clone of SIVmac, C8, and 4 macaques (group 13) were inoculated with the
chimeric virus SHIV-4. The animals were challenged ir with 10 MID50 of SIVsm
8-16 months later, when all monkeys were virus isolation negative but PCR-positive. The production of RANTES, MIP-la and MIP-1/ as well as the suppression
of viral replication was monitored in the supernatants of 3x106 PHA-stimulated
CD8+ T-cells purified from peripheral blood lymphocytes.
Results: Four of the vaccinated animals (three from group A and one from
group 13) were completely protected against the pathogenic SIVsm as determined by negative virus isolations and discriminative PCR. One monkey from
each group showed limited viral replication during the first month after challenge
but thereafter only the vaccine inoculum was detected. Four vaccinated animals
(two from each group) and all 10 control monkeys became readily infected. On the
day of challenge the 6 completely or partially protected monkeys showed higher
levels of RANTES (median 1580, range 1162-2169 pg/ml) and MIP-1 a (median 893 pg/ml, range 344-1480 pg/ml) than the infected animals (median 1000
pg RANTES/ml, range 354-1366 pg/ml and median 321 pg MIP-1 a/ml, range
215-635 pg/ml). Interestingly, already before vaccination the level of RANTES
(median 1742 pg/ml) and MIP-1 a (median 977 pg/ml) was high in the protected
monkeys in comparison with the infected animals (median 697 pg RANTES/ml
and 343 pg MIP-1 a/ml). Furthermore the supernatants from the resistant monkeys showed a high anti-viral suppressor activity (45-55%) while those from the
infected macaques gave lower inhibition (9-33%) of viral replication.
Conclusions: The monkeys vaccinated with live attenuated vaccines that resisted infectious SIV-challenge showed higher anti-viral suppressor activity and
P/-chemokine production than the infected animals at the time of challenge but
their chemokine production was high already before vaccination. This indicates
that /-chemokines play a role in protective immunity but also that genetic and/or
environmental factors influence their production.
S11240 DNA vaccine encoding an HIV epitope fused with HBV
surface antigen in rhesus macaques: Role of HIV specific
cytotoxic T lymphocytes
Sylvie Leborgne1, M.L. Michel2, A.M. Aubertin2, O. Dormont4, Y. Reviere1, R. Le
Grand4. 1 lnstitut Pasteur Unite V.I.C., Paris Cedex 15; 2lnstitut Pasteur Unite
R.E.G., Paris Cedex 15; 3Universite L. Pasteur LabodeVirologie, Strasbourg;

4CRSSA, CEA Service de Neurovorologie, Fontenay Auxro Ses, France
Objectives: Evaluation of the role of HIV specific immune response induced by
a DNA based vector a HIV-1 V3 epitope fused with a carrier antigen.
Background: DNA immunization offers a novel mean to induce humoral and
cellular immunity in inbred or in outbred animals, by mimicking natural viral infection. A DNA hepatitis B virus (HBV) envelope-based vector encoding a HIV-1 V3

epitope was validated in mice. After immunization, Rhesus monkeys developed
HBV and HIV specific humoral and cellular responses (Virol., 240 1998).
Methods: For IM and ID immunization, a plasmid was constructed that contained the middle and the small HBV-envelope proteins (pCMV-S2.S) under the
transcriptional control of the human cytomegalovirus (CMV) immediate-early promoter. The same construct was used in which part of the amino-terminal domain
of the middle protein was substituted with the variable domain V3 of HIV-1 Lai
envelope (pCMV-V3.S). Two protein-primed Rhesus monkeys were immunized
with pCMV-V3.S, whereas two naive animals received as control the pCMV-S2.S
construct. HBV and HIV specific humoral and cellular responses were followed
during the vaccination protocol. Four vaccinated monkeys and two control animals were challenged with SHIVsbg (AIDS Res.Hum.Retrovir, 13 1997). Viral
and biological markers were followed after injections.
Results: In the naive primates pCMV-S2.S injection first induced an HBVspecific cytotoxic response followed by the appearance of potentially protective
anti-HBs antibodies. In protein-primed monkeys, B-cell memory was successfully
boosted by DNA injection and animals subsequently developed a multispecific
cellular response. In those primates, HIV envelope-specific CTLp frequencies
were consistent with those reported in HIV-infected humans and in SIV-infected
primates. After the SHIVsbg challenge all Rhesus monkeys were infected. However, one of the two pCmv-V3.S immunized animals with the stronger HIV-specific
cellular response displayed a significantly lower viral load.
Conclusion: DNA-based immunization could be used to boost efficiently and
broaden the immune response in individuals immunized with conventionnal vaccines. Futhermore, results obtained with a single HIV epitope-based vaccination
suggest that DNA multispecific vaccines could be rationally designed to induce a
persitant and putatively protective immunity.
11241 Adenovirus-SIV env priming and boosting with a
synthetic peptide polymer from the C4 region of SIV
envelope induces strong cellular immune responses in
Macaques
Jean Patterson, K.M. Alrich, F.A. Robey, M. Robert-Guroff. NIH NCI DBS BRL
Bldg. 37, Rm. 6B-18, Bethesda, MD 20817, USA
To improve the immunogenicity of HIV and SIV subunit proteins, we are developing novel alternatives, including an a-helical, polymeric peptide (peptomer)
derived from the CD4 binding region of HIV-1 or SIV envelope. Not only is this
site highly conserved among HIV and SIV strains, it also contains T helper, B,
and CTL epitopes for presentation to the immune system, making it an attractive
candidate for vaccine design. Immune responses resulting from SIV peptomer
boosting following adenovirus (Ad) immunization, already shown effective at priming humoral, cellular and mucosal immune responses in non human primates,
were assessed in 9 rhesus macaques. Six were immunized twice with Ad-SIV
env recombinant. Three were subsequently boosted twice with SIV peptomer
and three with native SIV gp120, all in Ribi's adjuvant. Three control animals
received vector or adjuvant alone. Two of three animals from both peptomer and
native gp120 groups showed significant CTL responses after Ad immunization.
After boosting twice, CTL activity was enhanced for these macaques, indicating
a strong MHC class I restricted CD8+ response induced by both the recombinant
Ad and boosting immunogens. T cell proliferative responses were also measured.
Stimulation indices (Sl's) in response to SIV envelope antigens ranged from 4-13
for 4 of 6 macaques immunized with Ad-SIV env. Boosting with peptomer stimulated or dramatically enhanced responses for all 3 macaques, with peak Sl's
of 14-25. In contrast, native gp120 animals exhibited Sl's of 6 or less. Sl's of
controls were less than 2. While high titered SIV-specific neutralizing antibodies
were detected for the native gp120 group, none were elicited after two peptomer
boosts. A third boost of peptomer conjugated to alumina particles will be administrated. Such particles have generated strong neutralizing titers in rabbits after
one immunization. A novel SIV envelope peptomer elicits strong cellular immune
responses in macaques. By itself, peptomer presents CD4 binding site sequences
in native conformation, and when conjugated to alumina particles induces strong
humoral immunity in animal models. The protective efficacy of this approach will
subsequently be evaluated by intrarectal challenge with SIVmac251. This novel
synthetic peptide could prove to be an important component of an AIDS vaccine.
S11242 | Kinetics and persistence of CTL response in macaques
and mice injected with alvac-HIV (vCP205)
Catherine Caillet, S. Desforges, E. Trannoy. Pasteur Merieux Connaught 1541
Av. Marcel Merieux Marcyl'etoile 69280, France
Objectives: the aim of this study was to analyze both kinetics and persistence
of CTL response in macaques and mice immunized with alvac-HIV (vCP205)
expressing gpl20-MN LAI, gag-LAI and pro-LAI antigens.
Methods: two groups of 4 cynomolgus macaques were inoculated 3 times
with alvac-HIV (vCP205) administered either by the intramuscular route (group
1) or by the intravenous route (group 4). An additional group of 4 macaques
(group 3) received 5 intramuscular injections of alvac-HIV (vCP205) at months

MO, M1, M2, M4 and M8. Control groups of 2 macaques received the alvac vector
(cpPP) expressing no antigens (group2, im route and group 5, iv route). PBL were
collected before each injection and then monthly during 9 months. Specific CTL
were amplified in vitro by two consecutive stimulations with or without IL2. Their
specific activities were analyzed using autologous Herpes papio transformed B
cell lines infected with recombinant vaccinia viruses expressing different HIV
antigens (gpl20-MN LAI, gag-LAI, pro-LAI). A similar protocol was performed in