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Managing Acute HIV Infection Nucleic Acid Amplification Testing January 26, 2009. Nick Curry, MD, MPH Infectious Diseases Prevention Section Texas Department of State Health Services. Setting the Stage.

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Managing acute hiv infection nucleic acid amplification testing january 26 2009
Managing Acute HIV InfectionNucleic Acid Amplification TestingJanuary 26, 2009

Nick Curry, MD, MPH

Infectious Diseases Prevention Section

Texas Department of State Health Services


Setting the stage
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 stage1
Setting the Stage

  • ~ 6,400 new cases of HIV reported in Texas in 2007.

  • 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
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
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
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
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
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
Clinical Sensitivity and Specificity of the APTIMA HIV-1 Assay in a High Risk Population

Gen-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
Intended Use Review, Center for Biologics Evaluation and Research (CBER), FDA

  • 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


Acute HIV Review, Center for Biologics Evaluation and Research (CBER), FDA

Established Infection

RNA NAAT

p24

4th gen EIA

2nd & 3rd gen EIA

Western Blot

Less Sensitive EIA

ARS*

CD4

HIV Abs

Viremia

Genital Shedding

2

7

14

3

4

5

24

*Acute Retroviral Syndrome

Days

Weeks

After Pilcher, 2008


Detection range of hiv tests
Detection Range of HIV Tests Review, Center for Biologics Evaluation and Research (CBER), FDA

Weeks After Infection


NAAT Testing of Pooled Sera to Identify Acute HIV Infection Review, Center for Biologics Evaluation and Research (CBER), FDA (seronegative, NAAT positive)

After Leone, from International Society for Sexually Transmitted Disease Research, 2007


May 5, 2005 Review, Center for Biologics Evaluation and Research (CBER), FDA


Pooling and hiv rna testing

A B C D E F G H I Review, Center for Biologics Evaluation and Research (CBER), FDA

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

Pooling and HIV RNA testing

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
North Carolina New NAAT Assay and Pooling Algorithm Review, Center for Biologics Evaluation and Research (CBER), FDA

  • 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
Who performs HIV RNA NAAT in Texas? Review, Center for Biologics Evaluation and Research (CBER), FDA

  • 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 NAAT Summary Review, Center for Biologics Evaluation and Research (CBER), FDA

  • 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.


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