Presentation on theme: "Managing Acute HIV Infection Nucleic Acid Amplification Testing January 26, 2009 Nick Curry, MD, MPH Infectious Diseases Prevention Section Texas Department."— Presentation transcript:
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 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 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 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-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 Established Infection RNA NAAT p24 4 th gen EIA 2 nd & 3 rd gen EIA Western Blot Less Sensitive EIA CD4 HIV Abs Viremia Genital Shedding ARS* DaysWeeks *Acute Retroviral Syndrome After Pilcher, 2008
Detection Range of HIV Tests ACUTE SYMPTOMS HIV-1 RNA NAAT (2006) HIV EIA 1 ST (1985) & 2 ND ( ) Generation HIV EIA 3 RD (~ ) Generation Western Blot (1985) Weeks After Infection
NAAT Testing of Pooled Sera to Identify Acute HIV Infection (seronegative, NAAT positive) After Leone, from International Society for Sexually Transmitted Disease Research, 2007
May 5, 2005
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 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 ^Perform both screening and diagnostic assays *Will begin diagnostic assays in 2009 **Will request funding to begin diagnostic assay in 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.