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

24 Abstracts 11209-11213

12th World AIDS Conference

by a HIV 5' LTR, a portion of the HIV gag gene and the HIV RRE is expressed
in a cell line constitutively producing Tat. HIV p24 can only be detected when a
functional Rev is provided from a co-transfected plasmid. By inserting HERV-K
gag sequences instead of HIV gag, we confirmed that HERV-K gag expression
is under the control of a Rev/RRE like function. In this study, we have exchanged
the HIV RRE sequences by HERV-K sequences and tested for their ability to
replace the HIV Rev/RRE function in co-transfection experiments with Rev and
cORF expressing plasmids.
Results: We have identified an element with RRE function spanning parts of
the 3' U3 and the R region that is able to regulate Gag and Env expression from
subgenomic and full length expression vectors in a cORF dependent manner.
The element is designed RcRE.
Conclusion: We found that the protein expression of HERV-K is regulated in a
manner that has been described only for lentiviruses and human T-cell leukemia
viruses up to now. The localization is identical with that of the RxRE of HTLV I.
Therefore this regulation system seems to have evolved in virus that are thirty
million years older than HIV and HTLV.
11209 Increasing incidence of HTLV-II infection in Spain
Maite Gutierrez1, A. Machuca2, U. Soriano2, C. Tuset3, F. Merino4, L. Ortiz3.
HTLV Spanish Study Group; 1Service Microbiology, ISC-III, Calle Sinesio
Delgado 10 28029-Madrid; 2lnstituto Salud Carlos III, Madrid; 3Universidad Pais
Vasco, Bilbao; 4Hospital Clinico, Valencia, Spain
Objectives: To describe the main characteristics of subjects with HTLV-II infection
reported in Spain up to 31 December 1997, examining case report forms from
the HTLV National Registry database.
Material and Methods: The HTLV Spanish Study Group was founded in 1991,
and includes participants from 18 diagnostic centers distributed for all the Spanish geography. An annual meeting is organized since 1991, which provides the
opportunity to report and discuss the recent identified cases. Serological (EIA,
LIAs and DBL Western blot) and/or genetic (PCR) methods are used to confirm
HTLV-II infection.
Results: 192 cases of HTLV-II infection have been reported and confirmed to
date, being men 163 (85%). Thirty additional cases are still in the process to
be confirmed, and are not discussed in this report. Age ranged between 20 and
72-year old. No pediatric cases have been found. Only 12 (6%) were immigrants,
and one of them was co-infected with HIV-2. The remaining were Spanish native individuals, often with a past history of intravenous drug addition practices,
although 5 subjects had acquired HTLV-II through heterosexual contact, and
another through blood transfusion. In a national survey of HTLV infection among
pregnant women, 5 (0.07%) cases were identified, and all of them were typed
as HTLV-II, were former IDUs, and 4 being co-infected with HIV-1. No cases
of HTLV-II infection have been identified among blood donors in Spain. Clinical
symptoms potentially associated with HTLV-II were recognized in one individual
who developed a proximal myopathy. HIV-1 co-infection was found in 155 (80.7%)
subjects. From the total population, 10 (5.3%) already have died; all in association
with AIDS complications. The incidence of HTLV-II has risen in IDUs to 2% in the
last few years; and IDUs in jail seem to have the highest prevalence, suggesting
that virus spreading is occurring through needle-sharing.
Conclusion: HTLV-II infection seem to be spreading among Spanish IDUs in
the last few years, often in people already infected with HIV-1. HTLV-II instead of
HTLV-I is infecting HTLV seropositive pregnant women.
S11210 SIVcpz-ant causes non-escalating immune activation and
uses multiple co-receptors in chimpanzees
Luc Kestens1, Pascale Ondoa1, K. Vereecken', A. McKnight2, M.T. Dittmar3,
D. Davis1, J.L. Heeney4, G. Van Der Groen1. 1Department of Microbiology,
Institute of Tropical Medicine, Nationalestraat 155, B-2000 Antwerp, Belgium;
2Chester Beatty Laboratories London, UK; 3Heinrich-Pette-lnstitut Hamburg,
Germany; 4 Biomedical Primate Research center Rijswijck, The Netherlands
Objective: To follow-up the systemic immune activation in SIVcpz-ant infected
chimpanzees in relation to co-receptor usage.
Design: Prospective controlled study.
Methods: Systemic immune activation has been studied longitudinally in a
naturally infected (Ch-No) and an experimentally infected (Ch-Ni) chimpanzee
for 10 and 2 years respectively. Five non-infected chimpanzees served as controls. HLA-DR and CD38 expression were measured on CD8+ T cells in freshly
obtained whole blood. Co-receptor use of sequential cell-associated isolates
was studied using transfected U87 cell lines expressing human CD4 and the
chemokine receptors CCR1, CCR2b, CCR3, CCR5 and CXCR4. Recombinant
RANTES, MIPla and SDFla were used to assess their blocking capacity on in
vitro virus replication.
Results: Both SIVcpz-ant-infected chimpanzees showed no clinical signs of
infection and had normal CD4 T cell counts and normal proliferative responses to
mitogens and recall antigens. Compared to uninfected controls, Ch-No and Ch-Ni
have chronically increased HLA-DR and CD38 expression on CD8+ T cells but

markedly less than observed in HIV-infected humans. All sequential Ch-No virus
isolates displayed a dominant CCR5 co-receptor usage which was confirmed
by in vitro suppression of virus replication by RANTES, MIPla and MIP1l. In
Ch-No a progressive decrease of HLA-DR expression on CD8+ T cells over time
was inversely correlated with an increased tendency of SIVcpz-ant to broaden its
co-receptors usage. All SIVcpz-ant isolates of Ch-Ni displayed a less dominant
CCR5 usage than the isolates of Ch-No.

Conclusion: SIVcpz infection is associated with a non-escalating systemic
immune activation. All SIVcpz isolates use the CCR5 co-receptor. Longitudinally,
they cycle between sole use of CCR5 and heterogeneous use of all co-receptors
studied.
112111 Study of the phenotype of primary HIV-1 isolates and their
susceptibility to neutralization by polyclonal sera
Phillipe Nyambi', E. Beirnaert2, C. Dayaraj3, J. Kengasong2, S. Zolla-Pazner3,
G. Van Der Groen2. 1 VA Medical Center, 423 East 23rd St., Room 18124N, New
York NY 1001-5050; 3New York University Medical Center New York, USA;
2Department of Microbiology, Institute of Tropical Medicine Antwerp, Belgium
Objective: To study the correlation between syncytium induction in MT2 cells and
coreceptor usage of primary HIV-1 isolates, and to determine their susceptibility
to neutralization by homologous and heterologous polyclonal sera.
Materials and Methods: Sixteen HIV-1 isolates, 13 from group M (subtypes
A-H) and three from group O, with 12 homologous and 2 heterologous sera
were studied. The syncytium inducing properties of the viruses were investigated
in MT2 cell lines. Coreceptor usage (CCR5 and CXCR4) was determined on
GHOST cells (HOS cells with CD4, CCR5 or CXCR4 and GFP as the indicator
gene). Neutralization was performed with 3 day PHA-stimulated PBMCs. Serum
as well as isolate neutralization clusters were defined by spectral map analysis
(Nyambi et al, J Virol 1996; 70: 6235-43).
Results: The syncytium inducing abilities of the viruses correlated well with
coreceptor usage. Ten of 16 NSI isolates were CCR5-tropic (R5 type). Of the six
SI isolates, four were dual-tropic (using both CXCR4 and CCR5, X4R5 type), and
two were CXCR4-tropic (R4 type). The isolate neutralization clusters contained
either primary HIV-1 isolates of the R5 (cluster I and IV), R5 and X4R5 (cluster
II), X4 and X4R5 (cluster III) type of viruses. The total of the average neutralizing
capacity of sera from individuals infected with X4 and X4R5 was -1.8 for R5 and
+2.0 for X4 and X4R5 type of viruses, regardless the HIV-1 subtype they belong
to.
Conclusion: The syncytium inducing properties (NSI, SI on MT2 cells) correlated well with coreceptor usage on GHOST cells. NSI isolates were exclussively
R5, while SI isolates were either X4 or X4R5. Generalist potent sera neutralized
HIV-1 isolates irrespective of their coreceptor usage. Specialist potent sera of
individuals infected with X4 and X4R5 type of primary HIV-1 isolates neutralized
specialist X4 and X4R5 type better than R5 type of viruses, and vice versa.
|11212 Requirement of each glycan in the gp120 for maintaining
the infectivity of simian immunodeficiency virus (SIV)
Yoshiyuki Nagai1, Shinji Ohgimoto', T Shioda', K. Mori2, E.E. Nkayama1,
H. Hu1. 'Dept. of Viral Infection Inst. of Med. Sci. Univ of Tokyo Minato-ku,
Tokyo; 2National Inst. of Infectious diseases, Tsukuba, Japan
Objectives: To know the role of each N-linked oligosaccharide in infectivity of
SIVmac239.
Methods: Twenty-three mutant SIVmac239 constructs each lacking one of the
23 N-linked oligosaccharide chains in the gp120 envelope protein were generated
according to the standard in vitro mutagenesis method. Mutant viruses were recovered by transfection of each construct to SW480 cells followed by cocultivation
with MT4 cells.
Results: Compared with the wild-type parental virus for replication capability
in MT4 cells, the 23 mutants were either equally replicating, severely impaired
or faster replicating. The respective three different types of mutations did not
distribute randomly but clustered to particular regions in the primary amino acid
sequence of the gpl20. The faster replicating mutants exhibited a higher fusogenic
activity.
Conclusion: For maintaining SIV infectivity, each N-linked glycan of gp120 is
either dispensable, essential or down-regulating, depending on its location.
11213 Implication of the C terminal domain of SVmac251 nef
protein in the viral pathogenesis
Bernard La Font1, Y. Riviere2, L. Gloeckler1, C. Beyer1, B. Hurtrel3, A. Kirn1,
A.M. Aubertin1. ' Unite Inserm 74 - Institut de Virologie 3 Rue Koemberle,
Strasbough; 2lnstitut Pasteur Unite Vic, Paris; 3lnstitute Pastuer Oncologie
Virale, Paris, France
The inoculation of rhesus macaques with Simian immunodeficency Viruses (SIV)
results in a persistent infection leading to an AIDS like disease. However several molecularly cloned SIV were reported to be highly attenuated. Among them
SIVmacBK28 derived from the pathogenic SIVmac251 isolate can be used to
identify virulence determinants. Given that i) the net gene is important for the
maintenance of a high viral load in macaques, ii) the SIVmacBK28 nef ORF
possesses one nucleotide deletion compared to the nef gene of a pathogenic
clone SIVmac239 (this results in a frameshift and the formation of a truncated
Nef protein missing the 31 C terminal amino acids present in Nef SIVmac239),

we analysed the evolution of the BK28 nef gene in vivo.
Macaques were infected with SIVmacBK28-41, a virus with a BK28 genome
in which the premature stop codon present in the transmembrane (TM) glycoprotein gene was mutated to restore a full length gp41 TM, and the infection
was monitored by measuring the number of infected PBMC. At different time
points, the nef gene was amplified by PCR from PBMC or lymphoid organs cells
and sequenced. Different situations were observed during the follow up of 12