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

12th World AIDS Conference

Abstracts 11224-11228 27

Design: Equal infectious units of the HIV-1 subtype B strain LAI (IIIB) and
subtype E strain 90CR402 (E402) were mixed, and one chimpanzee each was inoculated IV (C-534) or cervically (C-470). After inoculation, virologic, immunologic
and hematologic parameters were evaluated periodically.
Methods: HIV-1 was isolated by coculture of chimpanzee PBMC with normal
human PBMC. The C2-V5 region of env in proviral DNA from PBMC or lymph
node cells was amplified by nested PCR using strain-specific and universal
primers; individual clones of the PCR products were classified as subtype B or
E by heteroduplex assay to determine relative proportions of the two strains.
Semi-quantitative PCR using serially diluted cellular DNA and quantification of
plasma RNA were used to assess viral burdens. Serum neutralization of infectivity
for PBMC of the two HIV-1 strains also was evaluated.
Results: After inoculation of HIV-1, both chimpanzees became infected, as
shown by virus isolation and seroconversion. Initially, only E402 was detected in
C-470's PBMC, and at 6 wks after infection, plasma RNA levels (700 copies/ml)
were characteristic of E402. In contrast, at 8 wks after infection, both E402 and
LAI (IIIB) proviruses were detected in C-534's PBMC, but plasma RNA levels
(20,000 copies/ml) were characteristic of the latter virus. By 40 wks after inoculation of C-470, LAI (IIIB) proviruses predominated in PBMC; and at 52 wks,
plasma RNA levels had increased to 32,000 copies/ml, indicative of LAI (IIIB).
C-470's neutralizing antibodies also mirrored the switch in the major virus; that is,
at 6 mos after infection, C-470's serum neutralized only E402, but at 12 months,
both E402 and LAI (IIIB) were neutralized.
Conclusion: Simultaneous mucosal or IV exposure of chimpanzees to two
distinct HIV-1 subtypes can result in infection with both viruses. Furthermore, the
most prevalent virus strain in PBMC and lymph nodes can change over time,
suggesting that there is a dynamic interaction between the viruses and/or immune
responses specific for the two strains.
11224 Early T cell dysfunctions during acute infection of
SIVmac251 infected Macaques
Laure Gigout, S. Lebel-Binay, B. Vaslin, R. Le Grand, D. Dormont. Service De
Neurovirologie, DSV/DRM/IPSC BP6, CEA, 92265 Fontenay AUX Roses Cedex,
France
Background: We aimed to characterize the early immune responses in blood
and lymph nodes after inoculation of cynomolgus macaques with a pathogenic
virus. We have thus investigated proliferative responses, cytokine expression and
T cell phenotyping.
Methods: Four cynomolgus macaques were inoculated i.v. with 4 AID50 of a
pathogenic isolate of SIVmac251. Peripheral blood mononuclear cells (PBMC)
and lymph node mononuclear cells (LNMC) were isolated during acute infection.
They were stimulated with optimal doses of ConA or of anti-CD3 mAbs and
the proliferative responses evaluated by incorporation of (3H) thymidine. They
were also phenotyped by double immuno-fluorescence labelling to define the
expression of activation markers (CD25, HLA-DR, CD71) and finally, RT-PCR
were performed to measure ex vivo lymphokine (IL-2, IL-4, IFN-y) and IL-10
mRNA profiles. Virological parameters were determined as well (plasmatic RNA,
p27 antigenemia, seric antibody titers and number of proviral DNA copies).
Results: All the animals exhibited a transient decrease in the proliferative
response at day 7 p.i. in PBMC and LNMC after anti-CD3 or ConA stimulation.
We also noted an increase of the percentage of CD4+CD25+ and CD4+CD71+
at day 7 p.i. in LNMC only. A transient decrease in IL-2 mRNA level was also
noted in LNMC at day 7 p.i. On the opposite, an increase in IFN-y and IL-4 mRNA
was observed in LNMC. In blood, IL-2 and IL-4 mRNA levels remain constant or
undetectable during all the follow-up, and IL-10 and IFN-y mRNA levels peaked
during the first month p.i. We are now exploring lymphokine mRNA profiles in
highly enriched TCD4+ and TCD8+ subpopulations.
Conclusions: These findings demonstrate divergent cytokine profiles between
blood and lymph nodes. Furthermore, they point out an early T-cell immune dysfunction in lymph nodes as attested by the decline in the proliferative responses
and the IL-2 mRNA level, concomitant with an increase in the percentage of
CD4+CD25+ cells.
| 11225} 3-Chemokine responses in bronchoalveolar lavages
during pathogenic and non-pathogenic SIV acute
infections
Philippe Caufour, R. Le Grand, A. Cheret, 0. Neildez, F. Matheux, B. Vaslin,
D. Dormont. CEA Service De Neurovirologie DSV/DRM, 92265 BPG Fontenay
AUX Roses Cedex, France
Objectives: We sought to analyse and characterize lymphocyte recruitment and
chemokine secretion in mononuclear cells obtained from bronchoalveolar lavage
(BALMCs) during the acute infection of macaques with an attenuated nef-deleted
SIV or a full pathogenic SIVmac 251.
Methods: Two groups of cynomolgus macaques were inoculated intravenously
respectively with a pathogenic isolate of SIVmac251 (seven animals) and with a
nef-deleted molecular clone derived from the BK28 clone (four animals). Spon
taneous chemokine production was assessed by ELISA in short term cultured
BALMC supernatants. The kinetics of hematological, virological and immunological changes were investigated simultaneously.
Results: The eleven animals became infected. The monkeys inoculated with
the nef-deleted SIV clone exhibited a significantly reduced virus load when compared to monkeys infected with pathogenic SIVmac 251 isolate. While a more
pronounced leukocyte recruitment was noticed in BALMC of the monkeys infected

with pathogenic SIVmac 251 isolate, no difference in SIV detection in BALMC
was observed between these groups. An increased production of MIP-la was
observed in the two groups of monkeys. However, a more important production
of this chemokine was detected in short term cultured BALMC supernatants of
monkeys infected with the attenuated virus. An increased production of RANTES
was detected in all nef-deleted virus infected monkeys and in only one animal
infected with the pathogenic virus.
Conclusions: The increased production of pchemokines occurring in BALMCs
of monkeys during the primary infection with SIV, more pronounced in monkeys
infected with attenuated virus, suggests a preserved or a more efficient antiviral
immune response in these monkeys. These results improve our understanding of
immune events that occur during live attenuated retroviral primary infection.
S11226 Lessons learned from comparing pathogenic and
non-pathogenic immunodeficiency virus-host systems
Reinhard Uurth, B. Beer, M. Baier, S. Holzammer, S. Norley.
Paul-Ehrlich-lnstitut; Paul-Ehrlich-STR.51-59; 63225 Langen, Germany
Despite years of intense study the precise reasons for the demise of the immune system characteristic of HIV infection of humans and SIVmac infection
of monkeys remains unknown. The viruses SIVagm and SIVsm, both of which
have been shown to cause immunodeficiency in heterologous species, do not
induce disease in their respective natural hosts, African green monkeys and sooty
mangabeys. This indicates that the natural hosts are themselves not susceptible
to the immunosuppressive effect of the viruses. Knowing the reasons for this
apparent resistance to disease, which has presumably developed over millennia
of coexistence, could shed light on pathogenesis mechanisms in HIV infection
and offer new opportunities for therapy and prophylaxis.
An analysis of the SIVagm/AGM system has so far failed to reveal any obvious
protective mechanisms. The immune response is quantitatively and qualitatively
similar to that observed during HIV-1 infection of humans. The in vivo mutation
rate corresponds to that of HIV and the peripheral virus load is in the same range
seen with HIV-1 and SIVmac during the asymptomatic phase. In contrast to the
situation n humans, the virus load in the lymph nodes of AGMsis no higher than
in the PBMC. Furthermore, there is no evidence of virus trapping at the surface of
the lymph node follicular dendritic cells and the lymph node architecture remains
intact. In contrast to the results obtained with attenuated SIVmac in neonatal
macaques, new-born AGMs were found to be no more susceptible to disease
following SIVagm infection than adults. Finally, although the AGMs possess an
unusually high percentage of CD8+ T-cells in circulation, their role in protection
from disease progression remains unclear.
Conclusions: Together, the data indicate that AGMs do not possess a mechanism for actively controlling the replication of SIVagm. However, it is likely that
the ability to maintain lymph node architecture in the face of continuous viral
replication plays a pivotal role in protection from disease.
11 227 Apoptosis of lymphocytes and Fas Ag expression in early
phase of SIVmac infection
Hiroshi Ichimura1, T.I. lida2, T.K. Kuwata2, M.U. Ui2, T.S. Shimada2,
J.I. Imanashi2, M.H. Hayami2. 152-2 Azeka Tsu-cho Kamigamo Kita-ku, Kyoto;
2Kyoto Prefectural University of Medicine, Japan
Objecives: To investigate the role of apoptosis in AIDS development, we have
longitudinally analyzed apoptosis of lymphocytes in SIVmac-infected macaques.
Here we report the changes in apoptosis induction and Fas, antigen expression
in lymphocytes in the SIVmac-infected macaques during the first 4 weeks post
infection (p.i.).
Methods and Results: At one week p.i., a transient decrease of the number of
peripheral CD4+ and CD8+ lymphocytes was observed. Flowcytometric analysis
showed that the rate of in vitro apoptosis of peripheral blood mononuclear cells
became higher on day 13 p.i. (more than 20%) than that before infection (around
10%) and was maintained in a higher level compared to that before infection.
TdT assay in lymph node sections showed that the number of apoptotic cells in
lymph nodes was from 5- to 20-fold higher on days 13 and 28 p.i. than those on
day 5 p.i. and before infection. The Fas antigen expression on peripheral CD4+
and CD8+ cells increased on day 8 p.i. and was maintained in a higher level
compared to that before infection.
Conclusion: Induction of apoptosis of lymphocytes in SIVmac-infected
macaques occurs at 2 weeks p.i., following the increase in Fas antigen expression
on lymphocytes. It is, therefore, suggested that the induction of apoptosis is not
closely involved in the transient decrease of CD4+ lymphocytes in early phase of
SIVmac infection.
S11228 1 A new pathogenic SHIV-cynomolgus monkey model for
evaluation of HIV vaccine candidates
Katsuaki Shinohara1, K. Sakai2, E. Takahashi3, T. Nakasone2, Y. Ami3,

S. Ando4, K. Someya2, N. Yoshimo2, Y. Sasaki5, Y. Suzaki3, L. Yichen6,
S. Yamazaki2, M. Honda2. 14-7-1 Gakuen, Musashimurayama-Shi Tokyo; 2AIDS
Research Center, NIID Tokyo; 3Div. Biosafety Control and Research, NIID Tokyo;
4 Toyama Perfectual Health Institute Toyama; 5Dept. Safety Research and
Biology, NIID Tokyo, Japan; 6 Virus Research Institute Inc. Cambridge, USA
There is no established pathogenic SHIV model in cynomolgus monkeys. We
developed a SHIV-cynomolgus monkey model using a new chimeric SHIV-C2/1