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

112 Abstracts 13133-13137

12th World AIDS Conference

C (34%) and E (10%) were found mainly in IDUs, also in STD patients and
blood donors. In addition, homosexuals in big cities were found to be infected by
subtype B HIV-1 and persons returned from African by subtype A and D 1. The
relationship between HIV strains in different risk groups were determined. The
lasting time of HIV epidemic in different regions were estimated according to the
"molecular clock" of HIV variation.
Discussions: The epidemic of HIV in China was initiated in the southwest
border region by subtype B strains from Myanmar followed by subtype E strain
from nearby countries and subtype C strains from India. The subtype B' were
further spread to the Central and Eastern China through IDUs and blood donors,
subtype C strains transmitted along the drug trafficking road to China's far west
region. While the subtype E strains were still limited to the border and coastal
regions.
13133 Genetic characterization of incident HIV-1 subtype B and
E strains from injecting drug users (IDUs) in Bangkok,
Thailand
Shambavi Subbarao1, S. Vanichseni2, T.D. Mastro3, D. Kitayaporn4,
S. Raktham2, N.L. Young3, L. Srisuwanvilai2, C.C. Luo5, C. Hartz5. 1Retrovirus
Disease Branch NSG 9 CDC, 1600 Clifton Road, Atlanta, GA 30333; 2Bangkok
Metropolitan Administration, Bangkok; 3US CDC & HIV/AIDS Collaboration,
Nonthaburi; 4HIV/AIDS Collaboration, Nonthaburi; 5Centers for Disease Control
& Prevention, Atlanta, GA, USA
Background: The initial 1988 epidemic among IDUs in Bangkok was largely due
to envelope (env) subtype B' (Thai B) strains, but subtype E has increased in
prevalence in recent years. Since 1995, HIV-1 seroconverting IDUs have been
identified in a prospective cohort study to determine the feasibility of conducting
an HIV vaccine efficacy trial in this setting. Genetic characterization of these
strains is required for the design of candidate HIV-1 vaccines.
Method: HIV-negative IDUs (n = 1,208) were evaluated by HIV EIA testing
every 4 months. Following an HIV-positive test, blood was obtained at time 0 and
months 1, 4, 8, 12, etc. Samples from each seroconvertor during 1995-97 were
characterized for HIV-1 subtype from env region DNA amplified either from lysed
PBMCs or reverse-transcribed RNA from plasma. Viral subtypes were determined
by phylogenetic analysis of 345 bases in the C2-V4 region of gp-120.
Results: Through December 1997, 101 IDUs became HIV-1 infected. Of 78
samples analyzed to date, 63 (81%) were subtype E strains and 15 (19%) were
subtype B. All subtype B strains clustered with B' (Thai B) strains. The mean intrasubtype nucleotide divergence for subtype E was 6.96% (range, 0.30-13.65) and
for subtype B was 15.33% (range, 3.64-29.25). The mean divergence between
the two subtypes was 28.90% (range 19.27-45.92). The GPGQ motif at the crown
of the V3 loop was present in 58 (92%) of 63 subtype E strains; other motifs were
GPGR (2), GPGK (2), and GPGE (1). The V3 crown displayed greater variation
among subtype B strains: GPGR (6 of 15), GQGR (4), GPGQ (3), and GLGR (2).
Conclusions: HIV-1 subtype E accounted for a majority of new infections
among Bangkok IDUs in 1995-97; all subtype B strains were B' (Thai B). Subtype
E strains displayed limited genetic diversity in the env region; while subtype B'
HIV-1 vaccine evaluated in this population would be challenged by two HIV-1
subtypes.
13134 Surveillance trends of HIV-1 subtypes B' and E
throughout Thailand, 1992-1997
Thongpoon Chaowanachan1, N.L. Young1, K. Limpakarnjanarat1,
K. Ungchusak2, P. Wasinrapee1, C.-P. Pau3, N. Kaewpunt1, 0. Suksripanich1,
T.D. Mastro2. HIV/AIDS Collaboration (PO Box 139) Nonthaburi 11000; 2CDC
and HIV/AIDS Collaboration, Nontahburi; 3Ministry of Public Health, Nonthaburi,
Thailand; 4Centers for Disease Control, Atlanta, GA, USA
Objective: To describe geographic and temporal trends of HIV-1 subtypes B'
(Thai B) and E among persons with heterosexual risk and injecting drug users
(IDUs).
Design: Multiple cross-sectional surveys.
Methods: Unlinked HIV-positive serum specimens were collected from persons with heterosexual risk (STD patients, antenatal clinic patients, female sex
workers) and IDUs during the 1992, 1993, 1995 and 1997 sentinel surveillance
surveys conducted in 12 provinces in the 4 regions of Thailand (north, northeast,
central and south). All blood samples were screened by EIA for HIV-1 at the
provincial sites. HIV-positive samples were sent to the HIV/AIDS Collaboration for
a supplemental EIA and HIV-1 subtype determination by V3-loop peptide enzyme
immunoassay (PEIA).
Results: Of 1202 HIV-positive specimens, 1142 (95%) were subtyped as B'
or E, and 60 specimens (5%) were nontypeable and excluded from the analysis
(42 were non-reactive and 18 were dually reactive). Among 800 heterosexuals,
767 (96%) had subtype E and 33 (4%) had B'. Among 342 IDUs, 198 (58%) had
E and 144 (42%) had B'. IDUs from the north and northeast of Thailand had
predominately subtype E (81%) with no significant trends over time. From 1992
to 1997, the proportion of IDUs with subtype E increased from 25% to 61% (P =

0.001) in the central region and from 15% to 41% (P = 0.004) in the south.
Conclusion: HIV-1 subtype E accounts for more than 95% of sexually acquired
infections in Thailand and a growing proportion of infections among IDUs. This
shift from B' to E among IDUs may be due to a combination of epidemiologic and
virologic factors. Prospective studies of IDUs in Thailand should help to clarify
this molecular epidemiologic trend.

S13135 Disease progression and mortality among HIV-infected
female sex workers in northern Thailand
Khanchit Limpakarnjanarat', P.H. Kilmarx', S. Korattana', J. Kaewkangwal1,
N.L. Young1, R. Srismith2, S. Saisorn2, T.D. Mastro1. 'HIV/AIDS Collaboration
DMS 6 Bldg Tivanon RD; Nonthaburi 11000; 2Chiang Rai Regional Hospital
Chiang Rai, Thailand
Background: HIV infection began to spread rapidly among female sex workers
in northern Thailand in the late 1980s. However, there are very limited data on
disease progression and mortality rates from Asia.
Methods: Female sex workers in Chiang Rai province were enrolled in a
cohort study from 1991 through 1994 and evaluated prospectively. Mortality was
ascertained by reports from co-workers and family members, and by reviewing
hospital records, public health office death certificates, and housing registration
records. Among women who were HIV-infected at enrollment, HIV infection was
presumed to have occurred one year after the initiation of sex work, or in 1989 at
the earliest.
Results: Of the 500 women enrolled, 160 (32%) were HIV-1 seropositive at enrollment and 32 (6%) seroconverted during follow-up. Nearly all infections (96%)
were with subtype E. Through 1997, 42 HIV-infected women died; of whom 39
were seropositive at enrollment and 3 were seroconvertors. The mortality was
25% after 7.5 years from presumed date of infection. Mean age at death was
27.2 years (range 18-50 years). Among 21 seroconvertors, CD4 lymphocyte
count declined a median of 4.3 cells/g/L per month; among 70 women who were
seropositive enrollment and alive, the median rate of decline was 3.3 per month;
and among 23 women who were HIV-infected at enrollment and died, the median
rate of decline was 9.3 per month. The mortality rate three years after first CD4
lymphocyte enumeration was 69% (9/13) among women whose first CD4 count
was <200, 17% (13/78) among those whose first CD4 count was 200-500, and
7% (3/46) among those whose first CD4 count was >500.
Conclusion: Rates of HIV infection and of HIV-associated mortality were high
in these sex workers, and substantial medical care and social support resources
are needed for these young women and their families. These rates of CD4 lymphocyte decline and mortality are similar to those seen in earlier studies of other
populations, risk groups, and HIV subtypes, and will be helpful for determining
prognosis in this population.
13136 The role of same-sex behavior in the HIV epidemic
among northern Thai men
Chris Beyrer1, P. Kunawararak2, C. Natpratan2, D.D. Celantano1, D. Hoover1,
C. Khamboonruang3, K.E. Nelson1. 1Johns Hopkins University, 615 North Wolfe
St Baltimore Maryland 21205, USA; 2Ministry of Public Health Chiangmai CM;
3Chiangmai University Chiangmai CM, Thailand
Objectives: Heterosexual exposure is a major risk factor for HIV infection among
Thai men. Same-sex behavior may be as well. We investigated the epidemiologic
roles male same-sex behavior may play in Thailand.
Methods: Two populations have been studied to assess risks and rates for
HIV infection, among northern Thai men-who-have-sex-with-men (MSM): military
conscripts and male sex workers. Multivariate regression models were used to
estimate the independent impact of covariates on the net risk of HIV-1 infection
among 1991-1995 conscripts.
Results: In a study of 2047 military recruits 134, 6.7%, reported one or more
male sex partners; 130/134, 97%, reported female sex partners. MSM were more
likely to have had any STD (OR 2.72), gonorrhea, syphilis, and NGU. Those
reporting >1 male partner were more likely to be HIV infected (OR 2.81). In 1995
conscripts, those reporting same sex behavior were significantly more likely to be
HIV infected (OR 2.78, 95% Cl 1.14, 6.50) when controlling for STDs, sex with
women, and CSW use. In 1991 sex with CSWs explained 90.9% of HIV infections,
sex with girlfriends 9.1%. In 1993, CSW sex explained 97.6% of infections. In
1995, CSW sex explained 72.8% of infections; and sex with other men 12.6%,
though only 6.7% of conscripts admitted these behaviors. Among 1,172 male sex
workers followed from 1989 to 1996 in northern Thailand, the HIV prevalence
was 20.1%, and HIV incidence was 11.9/100 PY. Risk factors for HIV infection
included inconsistent condom use and shorter work histories. Most of these men
reported sex with women (57%) and 13.5% were married.
Conclusions: These data suggest that Thai MSM are at greater risk for HIV
infection than are men who report only sex with women, and that the majority of
Thai MSM have sex with both men and women, making them a potential "bridge
population" as well as a target for preventive interventions.
S13137 The molecular epidemiology of HIV-1 infection in the
Philippines, 1985-1997
Mario Luis Santiago1 2, E.G. Santiago4, J.C. Hafalla3, M.A. Manalo4,
L. Orantia5, M.E. Borromeo6, K.H. Meyer2. 11516 10th Avenue South, #309,
Birmingham, AL 35205; 21ntl Health Institute, Brown University Providence, RI,
USA; 3Molecular Biology Lab, Res Inst Tromped, Alabang; 4HIV/AIDS Core

Team, Dept of Health, Manila; 5Homeward Haven, Ospital ng Maynila, Manila;
6National HIV/STD Control Program, Manila, Philippines
Background: Despite initial projections of rapid epidemic spread of HIV-1 in the
Philippines, epidemiologic surveillance from 1985-1997 reveal a stable low-transmission pattern characterized by a low HIV-prevalence (886 cases as of March
1997) and incidence (11.6 additional cases per year).