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

18 Abstracts 11178-11182

12th World AIDS Conference

Conclusions: The generation of reference clones for the globally prevalent F
and G subtypes of HIV-1 will aid in work targeted for vaccine and treatment, as
well as basic science. The finding of many recombinant viruses among randomly
selected strains argues for frequent occurrence of co-infections, and emphasises
the need for sequencing full genomes in situations where viruses are used for
clinical research.
11178 Mapping conserved antigenic epitopes shared by HIV-1
virions of different genetic subtypes (clades) by a new
virus-binding assay
Phillip N. Nyanbi1, M.K. Gorny1, L. Bastiani1, C. Williams', S. Zolla-Pazner2.
1New York University Medical Center, VA. Hospital, 423 East 23rd Street, Rm
18124, New York, New York 10010; 2N. YU. & VA. Medical Centers, New York,
NY, USA
Objective: To determine the ability of monoclonal antibodies (mAbs) to bind to
intact HIV-1 virions of different clades in a newly developed virus-binding assay.
Materials and Methods: Fourteen human mAbs derived from HIV-1-infected
persons were used, including five to the V3 loop, three to the CD4 binding domain
(CD4bd), and two each to V2, C5 and gp41. Anti-HIV-1 pooled immunoglobulin
(HIVIG) from infected persons was used as a positive control. Culture supernatants from normal, PHA-stimulated peripheral blood mononuclear cells infected
with HIV-1 primary isolates were used as the source of virus. Nine isolates were
used, four from clade B and one each from clades A, D, F, G and H. The Abs
were coated onto microtiter wells followed by addition of virus. Bound virus was
detected after lysis by testing for p24 antigen with a non-commercial p24 ELISA.
Results: HIVIG bound all the isolates tested, irrespective of clades. Similarly,
the anti-C5 mAbs bound isolates of all the clades tested suggesting that the C5
region is well-exposed on the viral surface. The anti-V3 mAbs strongly bound
the four clade B viruses tested and bound viruses from the non-B clade tested
although binding was weaker and more sporadic than with clade B strains. Binding
by anti-V3 mAbs did not distinguish between CXCR4- and CCR5-tropic viruses,
suggesting that the V3 loops of these two categories of viruses are similarly
exposed on the surface of these virions. Only weak and sporadic binding of all
viruses was detected with anti-CD4bd, anti-V2, and anti-gp41 mAbs.
Conclusion: Using a new virus-binding assay, isolates of different clades were
shown to share conserved antigenic epitopes. Of the epitopes studied that are
exposed on the virus surface, C5 appears to be the most conserved among
clades. V3 is exposed on the surface of both CXCR4- and CCR5-tropic viruses
and some V3 epitopes are shared across clades. Several epitopes in the CD4bd,
V2 and gp41 are not exposed on the viral surface.
429* / 11179 Genetic recombination of HIV-1 strains identified in
China
Yiming Shaol, L. Su2, F. Zhao2, H. Xing2, Y.Z. Zhang3, H. Wolf4, L.L. Zhang5.
127 Nan Wei Avenue Beijing 100050; 2National AIDS Reference Lab (NARL)
Beijing; 3Xinjianmg Health Anti-Epidemic Station Urumchi; 5Sichuan Health
Anti-Epidemic Station, Chengdu, PR China; 4 University of Regensburg
Regensburg, Germany
Objective: To look for possible recombination of HIV-1 strains in China.
Design: Cloning and sequencing of multiple regions HIV-1 strains in areas
where more than two subtypes of HIV are circulating.
Methods: The blood samples were collected from the HIV infected individuals
in areas where epidemic of more than two subtypes of HIV1 were found. The
HIV env, tat, vpu and nef gene were amplified by nested PCR from PMCs and
directly sequenced and analyzed. The large fragments of the HIV strains were
cloned and analyzed by HMA method and sequencing of multiple regions was
performed in some of samples.
Results: The HMA and sequence analysis were performed to the 50 HIV1
strains collected in the subtypes B' and C epidemic areas of China. No evidence
of recombination after sequencing in env, nef and vpu regions were found. The
recombinant HIV-1 strains between the subtype B' and C were found in 12 of
the 50 (24%) samples when the first exon of tat gene was sequenced. The large
fragments (5-9 kb) from the recombinant strains were cloned. Systematic HMA
and sequence analysis were performed for further clarification of the recombinant viruses. The biological characterization of these strains were conducted in
comparision with their parental subtype B' and C strains.
Conclusion: The recombinant HIV1 strains between subtype B' and C were
first identified in Sichuan province of Southwest China. Later very similar recombinant HIV-1 strains were also found in Xinjiang Autonomous region, which
strongly indicates the correlation between these two HIV epidemic regions. Epidemiological investigation and Drug Control information proved the existence a
drug trafficking route linking the two provinces in thousands kilometers away.
|11180 No differences in Mexico between HIV-1 subtype B, sexual
preferences and routes of transmission

Eduardo Vasquez-Valls1, J.J. Sierra-G. De Quevedo1, F.C. Lopez-Marquez1,
M. Escoto-Delgadillo1, P.I. Campos-Lopez2. I1nstituto Mexican Del Seguro
Social, Guadalajara; 2Consejo Estatal Prevencion Del Sida, 2 Jalisco,
Guadalajara;, Mexico
Objective: To identify the association between the HIV-1 subtype B, sexual
preferences and routes of transmission.

Methods: Clinical histories and blood samples were obtained from 308 HIV
seropositives, 194 men and 114 women, they were clasiffied in order to their
sexual preference and route of HIV transmission. The sera were tested by enzyme
-linked immunosorbent assay (ELISA) with synthetic peptides 10 aminoacides
long, from the C2V3 region of the HIV-1 subtypes A, B, C, D and E. Nested
polymerase chain reaction (PCR) amplification was made as a comparative
test.
Results: Of all participants, 155 (50.32%) refered to have a homosexual preference; 115 (37.33%) were heterosexual and 38 (12.33%) were bisexual. Out of
which 274 (88.96%) were positive to subtype B, and 34 (11.03%) to another no B
subtype. Among B positives, 174 (63.50%) acquired the HIV by sexual contact;
57 (20.80%) by blood transfussion and 43 (15.69%) by perinatal route. Of the no
B cases, 24 (70.58%) acquired the HIV-1 by sexual route; 9 (26.47%) by blood
transfussion and one (2.94%) trough vertical transmission (p = NS). V3 serology
and nested PCR amplification correlation was 90.1% for subtype B.
Conclusion: In this sample, we do not find any association between the B sutype and the sexual preference or route of transmission between the seropositves
in the west of Mexico.
11181 1 The global spread of subtypes and intersubtype
recombinant HIV-1
Francine E. McCutchan1, D.L. Birx2. 1Henry M. Jackson Foundation, 1600 East
Gude Drive, Rockville, MD 20850; 2Division of Retrovirology, Walter Reed Army
Institute of Research, Rockville, MD, USA
Background: The identification of globally prevalent HIV-1 strains is an important
element of HIV-1 diagnosis, therapy and prevention. The pandemic is composed
of multiple subtypes and a variety of inter-subtype recombinant forms that are not
easily distinguished by partial genome sequencing. An increasing proportion of
international HIV-1 strains are now characterized by full-genome sequencing, and
the resultant database has prompted revisions of subtype classification and new
awareness of several inter-subtype recombinant forms that are undergoing epidemic spread. Frequent compilation and review of a rapidly expanding database
of HIV-1 sequences will be required to fully integrate new findings and to focus
research on HIV-1 subtypes and recombinants of global importance.
Methods: Virtually full-length HIV-1 genomes are amplified using polymerase
chain reaction from primary virus cultures on peripheral blood mononuclear cells
and are sequenced using fluorescent dye terminators and automated DNA sequencers. Data analysis is with maximum likelihood or maximum parsimony with
bootscanning for identification and mapping of recombinants.
Results: Some HIV-1 "subtypes" identified by partial genome sequencing are
actually recombinants and some recombinants are more globally prevalent than
subtypes. In some recently completed regional studies in Africa, even partial
genome sequencing was sufficient to establish that inter-subtype recombinant
strains outnumber subtypes. The identification of multiple recombinant strains,
each recovered from more than one individual, suggests that the spread of
recombinants is a major facet of the HIV-1 epidemic in some locations.
Conclusion: The contribution of inter-subtype recombination to HIV-1 diversity
is currently underestimated, particularly in parts of sub-Saharan Africa. The epidemic spread of several intersubtype recombinant HIV-1 should be considered,
along with the subtypes, in planning for diagnosis, treatment, and prevention.
Characterization of globally prevalent strains by full-length genome sequencing
should be continued and expanded.
S11182 Distribution of HIV-1 subtypes among HIV-1 positive
tuberculosis (TB) patients in the interior of C6te d'lvoire
John Nkengasong', L. Abouya1, M. Kalou1, D. Coulibaly2, C. Pau3,
M.Y. Borget1, E. Boateng', M. Sassan-Morokro1, R. Respess3, R. Coulibaly2,
S.Z. Wiktor3, A.E. Greenburg3, M. Rayfield3. 101 BP 1712 Abidjan 01, Project
Retro-CI, Abidjan; 2National AIDS/STD/TB Control Program, Adibjan, Cote d'
Ivoire; 3Centers for Disease Control Prevention, Atlanta, USA
Objective: To describe the distribution of genetic subtypes of HIV-1 strains in
different regions of C6te d'lvoire.
Methods: Plasma and peripheral blood mononuclear cells (PBMC) were obtained from HIV-1-seropositive TB patients in all the TB outpatient clinics in
the interior of Cbte d'lvoire including Abengourou (n = 27), Bouake (n = 49),
Daloa (n = 24), Korhogo (n = 31), Gagnoa (n = 12), and Man (n = 29). Plasma
samples were tested by a V3-loop peptide enzyme immunoassay (PEIA) that
uses consensus synthetic V3-loop peptides derived from subtype A strains from
Abidjan, and other HIV-1 subtypes (B, C, D, E, F, G) within group M viruses, and
one HIV-1 group O peptide. PBMC were tested by a restriction fragment length
polymorphism (RFLP) assay that involves a sequential endonuclease digestion of
a 297-base pair PCR fragment using Alul, Bcll, and Scal to segregate the HIV-1
viral strains into distinct subtypes. DNA sequencing of the protease or env genes
was performed on all samples discordant in the two assays as well as a random
sample of the concordant samples.
Results: Of the 171 specimens, three were PCR-negative and 168 PCR-pos
itive. Of the PCR-positive samples 147 (88%) were classified as subtype A by
RFLP and 21 were untypeable. Of the 147 RFLP subtype A samples, 137 (93%)
were subtyped A by PEIA, three, two, and five were classified as subtype C, D,
and F by PEIA, respectively. All 21 untypeable samples were subtype A by both
PEIA and by protease sequencing. Sequencing of the env gene classified the 10
PEIA non-subtype A samples as three As, two Ds and five Gs. Sequencing of
a subset of 10 concordant samples confirmed them all as subtype A. Therefore,