Major Sutchana Tabprasit Armed Forces Research Institute of Medical Sciences (AFRIMS),

ARMED FORCES RESEARCH INSTITUTE OF MEDICAL SCIENCES

XVIII International AIDS Conference, July 18-23 2010, Vienna Austria

Recent Trends in estimated HIV-1

Incidence among Royal Thai Army (RTA)

conscripts from 2005-2009 in Thailand

Major Sutchana TabprasitArmed Forces Research Institute of Medical Sciences (AFRIMS),

Royal Thai Army (RTA), Bangkok, Thailand



Primary HIV-1 Infection

• Acute infection

• Rapid viral replication

• 80-90% develop an acute syndrome

characterized by flu-like symptoms

• Broad HIV-1 specific immune response



Recent HIV-1 Infection (Incidence)

• Difference of HIV-1 antibody in various aspects

- Titer

- Proportion

- Isotype (avidity)



Adults and children estimated to be living with HIV, 2008

UNAIDS. 2009 Report on the global AIDS epidemic



Estimated number of adults and children newly infected with HIV, 2008

UNAIDS. 2009 Report on the global AIDS epidemic



Pre-seroconversion •HIV-1 RNA / DNA

•p24 Antigen

Methods for Detection Early HIV Infection (1)



Post-seroconversion •Less sensitive EIAs

• IgG-capture BED-EIA

• Avidity assays

• Anti-p24 IgG3 Antibodies

Methods for Detection Early HIV Infection (2)



Advantages of HIV-1 Incidence

• To monitor the effectiveness of the national

prevention and control programs• To determine active area of HIV transmission• To design the possibility to conduct HIV

vaccine trail



-To estimate the HIV-1 incidence

among the Royal Thai Army (RTA)

conscripts

Objective



Thailand



Recruitment of young Thai males occurs in April each year

60,000Males/year



HIV-1 SEROPREVALENCE OF YOUNG MEN ENTERING THE ROYAL THAI ARMY 1991-20094.5

0

0.5

1

1.5

2

2.5

3

3.5

4

1991199219931994199519961997199819992000200120022003200420052006200720082009

Year

HIV

-1

Sero

pre

vale

nce 2.9

3.53.7

3.02.4

2.11.9

1.61.3

1.20.70.70.

60.50.

50.5 0.50.50.5



The dot density of seroprevalence

among recruits in the Royal Thai Army

(RTA), 2005-2009.

Positive = 1,316 dots

Prevalence = 1,316/268,504 (0.5%)

1 dot = 1 prevalent

case



HIV Seropositive Detection From 2005-2009

R NRELISA I

Positive NIndeterminateWB/

ELISA II and III

BED-EIA

1,316

268,504

149



IgG- Capture HIV-EIA



Principles of IgG- Capture HIV-EIA

96-well plate is coated with goat anti-human

IgG



1. add specimen

IgG antibodies from plasma/serum

2. add Biotinylated HIV-1 BED peptide (gp41)

3. add Streptavidin–HRP Conjugate 4. add substrate




Read at wavelength 450 nm

with reference wavelength

630-650 nm

Spectrophotom

eter

Plat

e




Assay Validation : Run Control

R2

OD-N = OD/ Median OD of Calibrator



The Algorithm of IgG Capture HIV-EIA Confirmed HIV-seropositive

specimensTest in single

If ODn > 1.2 Long-term Seroconversion

If ODn ≤ 1.2Repeat test in triplicate

(Confirmatory)

If Median ODn > 0.8 Long-term Seroconversion

If Median ODn ≤ 0.8 Recent Seroconversion



Results

Figure 1: HIV incidences at time of entry into the RTA 2005-2009

Perc

en

t p

er

year

2005 2006 2007 2008 2009

0.14

0.19

0.20

0.26

0.25

Year



Table 1: HIV-1 incidence among the RTA Conscripts From 2005-2009 by demographic factors

Demographic FactorsNumber of Conscripts

Number of HIV-1 positive (Seroprevalen

ce)

Number of BED-CEIA positive

Incidence(95%

confidence interval)

Age

18 – 20 26,676 87 (0.33) 27 0.19(0.12 – 0.27)

21 190,360 828 (0.43) 2030.20 (0.17 –

0.22)

22 – 30 40,266 335 (0.83) 700.33 (0.25 –

0.40)

Education

0 – 6 68,131 471 (0.69) 960.25 (0.20 –

0.30)

7 – 9 88,096 379 (0.42) 790.15 (0.12 –

0.19)

>9 102,274 406 (0.38) 1270.25 (0.21 –

0.29)

Marital Status

Single 209,670 1,057 (0.50) 2600.24 (0.21 –

0.27)

Married 47,525 198 (0.42) 420.13 (0.09 –

0.17)



Summary

Increasing trend of HIV incidence in the recent

years alerts the active program for HIV prevention

and control programs in Thailand

HIV incidence was higher in recruited subjects with

older age. (22-30 years)

IgG capture BED is a promising predictor to

estimate HIV incidence in the future.



Acknowledgement

• Conscripts of the Royal Thai Army

• Armed Forces Research Institute of Medical

Sciences (AFRIMS)

• Army Institute of Pathology, King Mongkut

Medical Center

• Bureau of Epidemiology, Department of

Disease Control of Ministry of Public Health

(MOPH)

• Thailand MOPH - U.S. Centers for Disease

Control and Prevention (CDC) Collaboration



Thank you so much



www.nrl.gov.au



Early HIV Infection

Adapted from Parekh BS, McDougal JS. Indian J Med Res 2005;121(4):510-518.



Methods for Estimating HIV Incidence

www.nrl.gov.au



155 days

Level

Time since infection

Difference between BED-CEIA and HIV screening test



BED Branch Peptide Antigen



Prevalence Formula

Number of HIV-1 infection

Number of total in the survey100P =



Adjustment of Incidence Formula

R -ɛP

(R/2) + N(w/365) - ɛN - ɛP/2)

W=155 days

R=Total testing recent in the BED-CEIA

N=Total testing HIV negative

P=Total testing HIV positive

ɛ=False recent rate in those with ling term

(>2weeks) infection

100I =



Plate Plan For Sample



Acceptable ODn Ranges of

Controls and Calibrator

Acceptable Median OD Ranges of

Controls and Calibrator



Highly active antiretroviral therapy (HAART)

Combination chemotherapy for HIV infection

consisting of reverse transcriptase inhibitors

and a viral protease inhibitor.

Produce marked increase in peripheral blood

CD4+ T cells and decreases in HIV plasma RNA

copy number.

Reduce plasma virus titers to below

detectable levels for more than 1 year and

slow the progression of HIV disease.



Specificity Adjustment (Hargrove et al)

Major Sutchana Tabprasit Armed Forces Research Institute of Medical Sciences (AFRIMS),

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