Post on 27-Mar-2015
Managing Acute HIV Infection
Nucleic Acid Amplification TestingJanuary 26, 2009
Nick Curry, MD, MPH
Infectious Diseases Prevention Section
Texas Department of State Health Services
Setting the Stage
• In Texas, >25% of those initially diagnosed as HIV-infected, receive a diagnosis of AIDS within one month of the HIV diagnosis.
• Several studies have demonstrated that fifty percent or more of HIV transmission is due to acutely infected sources.
• Period of acute infection associated with high viral load.
Setting the Stage• ~ 4,600 new cases of HIV reported in
Texas in 2006.
• Black females are nineteen times more likely to be diagnosed with HIV when compared to white females today.
• Black males are five times more likely to be diagnosed with HIV when compared to white males.
Definition of Acute HIV Infection
• Time period following infection with HIV during which HIV can be detected in blood but antibodies to HIV are not detected
OR
• Window period when routine HIV antibody tests (EIAs) are negative but HIV can be detected in blood
What is the Rationale for Detecting Acute Infection?
• Interruption of HIV Transmission From Highly Infectious Individuals using NAAT and rapid DIS response
• Improved HIV Infection Diagnosis• Earlier and Appropriate Clinical
Management of Acutely Infected Persons• Enhanced HIV Surveillance• Improved Assessment of Epidemiologic
Trends
What is a nucleic acid amplification test?
• It is a test for the presence of HIV, not antibodies to HIV.
• It detects HIV infection before any antibody test can do so.
• It identifies the presence of HIV RNA, the nucleic acid which caries the HIV genetic information.
• It amplifies the HIV RNA for enhanced detection.• It is highly sensitive and specific.• It requires plasma (or serum) specimens.• It is approved as a diagnostic test, and can thus
replace the Western Blot for confirmation.
Clinical Genetic Amplification for HIV
• Nucleic Acid Amplified Test (NAAT) Examples– Only one FDA approved diagnostic test – Transcription Mediated Amplification (TMA) -
APTIMA® HIV-1 RNA Qualitative Assay by GenProbe (2006)
• Specificity and sensitivity 100% in high-risk populations @ 100 copies/ml
• Earliest possible detection of infection• Detects all major groups of HIV-1• Turnaround 3-7 days
Diagnostic Nucleic Acid Amplification for HIV
• Transcription Mediated Amplification (TMA) – Uses RNA Polymerase and Reverse Transcriptase; can amplify RNA or DNA targets; isothermal
Clinical Sensitivity and Specificity of the
APTIMA HIV-1 Assay in a High Risk Population
Gen-ProbeGen-Probe
Jay Epstein, M.D., Director, Office of Blood Research and Review, Center for
Biologics Evaluation and Research (CBER), FDA
• "This test also can detect infection with HIV-1 earlier than HIV antibody tests when used to detect primary HIV-1 infection.“
• “This test has important implications for medical diagnostic use because it could be a potential alternative to the traditional Western blot test now used for confirmation of HIV-1 infection when screening tests for HIV-1 antibodies are positive.”
Intended Use
• It is intended for use as an aid in the diagnosis of HIV-1 infection, including acute or primary infection. Presence of HIV-1 RNA in plasma of patients without antibodies to HIV-1 is indicative of acute or primary HIV-1 infections
• May also be used as an additional test, when it is reactive, to confirm HIV-1 infection in an individual whose specimen is repeatedly reactive for HIV-1 antibodies
Gen-Probe
2
Acute HIV Acute HIV
3 4 57 14 24
Established InfectionEstablished Infection
RNA NAATp244th gen EIA2nd & 3rd gen EIAWestern BlotLess Sensitive EIA
CD4HIV Abs
Viremia
Genital Shedding
ARS*
Days Weeks
*Acute Retroviral Syndrome
After Pilcher, 2008
Detection Range of HIV Tests
ACUTESYMPTOMS
HIV-1 RNA NAAT (2006)
HIV EIA 1ST (1985) & 2ND (1997-98) Generation
HIV EIA 3RD (~2002-2003) Generation
Western Blot (1985)
1 2 3 4 5 6 7Weeks After Infection
NAAT Testing of Pooled Sera to Identify Acute HIV Infection
(seronegative, NAAT positive)Pooled HIV RNA Testing: Yields
15%NYC 3 STD ClinicsNew York City
10%6/1553 (0.39%)STD clinicWashington DC
5%4/2128 (0.19%)STD clinics, community testing and drug treatment
Atlanta
00/15000STD clinicsMaryland (not Baltimore)
7.1%1/1698 (0.06%)Men tested in 3 STD ClinicsLos Angeles
10.5%11/2722 (0.40%)SF STD Clinic PatientsSan Francisco
13.5%21/5995 (0.35%)Men who have sex with men tested through PHSKC
Public-Health Seattle & King County
4%23/109,250 (0.02%)All persons tested for HIV via North Carolina DOH
North Carolina
Increase in Testing Yield
Prevalence HIV RNA+/EIA-
PopulationProgram
After Leone, from International Society for Sexually Transmitted Disease Research, 2007
May 5, 2005
Pooling and HIV RNA testing
A B C D E F G H I
1 2 3 4 5 6 7 8 9 10
A B C D E F G H I
A B C D E F G H I A B C D E F G H I
90 individual HIV antibody negative or WB indeterminate specimens
9 intermediate pools (10 specimens)
1 master pool (90 specimens)
North Carolina New NAAT Assay and Pooling Algorithm
• GenProbe APTIMA HIV-1 RNA NAAT assay
• Hamilton STARlet robotic pipetting instrument
• Reduced pool size (80 samples/pool)
• Increased sensitivity for HIV-1 NAAT
Myra Brinson - North Carolina Laboratory of Public Health, 2008
Who performs HIV RNA NAAT in Texas?
• Various private reference labs^• Dallas County Department of Health and
Human Services*• Houston Department of Health and Human
Services*• DSHS Laboratory**• Blood banks and organ donation centers@
^Perform both screening and diagnostic assays*Will begin diagnostic assays in 2009**Will request funding to begin diagnostic assay in 2009.@Perform screening assays
HIV-1 NAAT Summary• HIV-1 RNA NAAT can contribute to eliminating the
chain of HIV transmission.• HIV-1 RNA NAAT provides an option for early clinical
management of cases.• HIV-1 RNA NAAT will identify at least 2-3 acute
infections for every 10,000 specimens tested in high prevalence geographic areas.
• HIV-1 RNA NAAT expected to become a standard for HIV diagnosis within the next 2-3 years.
• HIV-1 RNA NAAT can replace the Western Blot as the confirmatory assay.