Learning Objectives. New HIV Testing Algorithm from CDC. Overview of HIV infection and disease 3/15/2016

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1 New HIV Testing Algorithm from CDC ASCLS-Michigan March 31, 2016 Dr. Kathleen Hoag Learning Objectives Following attendance and review of material provided, attendees will be able to: 1. Describe the new testing algorithm for HIV recommended by the CDC. 2. Explain how update HIV testing can distinguish HIV-1 versus HIV-2 infection. 3. Provide an overview of HIV infection and disease progression start here Overview of HIV infection and disease Human Immunodeficiency Virus (HIV) exists as two separate viruses, HIV-1 and HIV-2 HIV-1 is the most common in the U.S., but HIV- 2 is clinically relevant HIV primarily infects CD4 + T cells, but also antigen-presenting cells such as macrophages and dendritic cells HIV infection is the cause of Acquired Immune Deficiency Syndrome, or AIDS Diagnoses of HIV Infection among Adults and Adolescents, by Sex, United States and 6 Dependent Areas Note. Data include persons with a diagnosis of HIV infection regardless of stage of disease at diagnosis. All displayed data have been statistically adjusted to account for reporting delays, but not for incomplete reporting. Diagnoses of HIV Infection among Adults and Adolescents, by Sex and Transmission Category, 2014 United States and 6 Dependent Areas Rates of Diagnoses of HIV Infection among Adults and Adolescents, 2014 United States and 6 Dependent Areas N = 44,609 Total Rate = 16.6 Note. Data include persons with a diagnosis of HIV infection regardless of stage of disease at diagnosis. All displayed data have been statistically adjusted to account for reporting delays and missing transmission category, but not for incomplete reporting. a Heterosexual contact with a person known to have, or to be at high risk for, HIV infection. b Includes hemophilia, blood transfusion, perinatal exposure, and risk factor not reported or not identified. Note. Data include persons with a diagnosis of HIV infection regardless of stage of disease at diagnosis. All displayed data have been statistically adjusted to account for reporting delays, but not for incomplete reporting. 1

3/15/2016 Rates of Children Aged <13 Years Living with Diagnosed HIV Infection, Year-end 2013 United States and 6

6 HIV Virus Structure Retrovirus with RNA genome (2 identical strands) that is copied into DNA by RT and integrated

Data include persons with a diagnosis of HIV infection regardless of stage of disease at diagnosis.

HIV Targeting of Immune Cells HIV gp120 protein forms knobs that protrude from the viral envelope and bind CD4 and a

initiate infection at mucosal sites of entry by binding to CCR5, and preferentially infect M and dendritic cells (as

2 3/15/2016 Rates of Children Aged <13 Years Living with Diagnosed HIV Infection, Year-end 2013 United States and 6 Dependent Areas N = 2,434 Total Rate = 4.6 HIV Virus Structure Retrovirus with RNA genome (2 identical strands) that is copied into DNA by RT and integrated into host genome RNA is surrounded by a nucleocapsid and an envelope Note. Data include persons with a diagnosis of HIV infection regardless of stage of disease at diagnosis. All displayed data have been statistically adjusted to account for reporting delays, but not for incomplete reporting. HIV Targeting of Immune Cells HIV gp120 protein forms knobs that protrude from the viral envelope and bind CD4 and a chemokine receptor Any cell expressing CD4 is a target of HIV HIV Lifecycle Macrophage-tropic HIV strains generally initiate infection at mucosal sites of entry by binding to CCR5, and preferentially infect M and dendritic cells (as well as CD4+ T cells) Lymphocyte-tropic HIV strains preferentially bind CXCR4 and infect CD4+ T lymphocytes (later in infection; hastens progression to AIDS) Immune Response to HIV Acute Infection Clinical Latency Precipitous Loss of CD4+ T cells in HIV Infection Leads to AIDS AIDS 2

3 HIV diagnosis in high risk adults and children >24 months old From 2004 to 2014, CDC recommended: Initial EIA serology test of sample (serum, plasma, or oral exudate) from high-risk individual If negative, report as negative If positive, repeat in duplicate on same serum sample If negative on both repeats, report as negative If 2 of 3 tests from same serum sample are positive, send for confirmatory testing Confirmatory testing = either HIV-1 Western Blot or HIV-1 IFA (viral nucleic acid testing for HIV-1 RNA later deemed acceptable) Limitations of 2004 HIV diagnosis recommendations 1. Relying on confirmatory testing by western blot or immunofluorescence assay can result in false-negative or indeterminant results in early HIV infection ART therapy now recommended in early diagnosis 2. The majority of HIV-2 infections were misclassified as HIV-1 by the 2004 testing algorithm Improvements to HIV testing over time Branson, B.M. et al., Laboratory testing for the diagnosis of HIV infection: updated recommendations. Centers for Disease Control and Prevention (U.S.); Association of Public Health Laboratories; June 27, 2014; Figure 1, p. 11 (stacks.cdc.gov/view/cdc/23447) Improvements in HIV diagnostic assay generations First generation detected only IgG antibody to HIV-1 in human cell lysate Second generation detected only IgG antibody to HIV-1 synthetic or recombinant protein antigens Third generation used synthetic or recombinant HIV-1 & HIV-2 protein antigens to detect IgM or IgG in patient sample Fourth generation also known as HIV combo assays are 3 rd generation PLUS monoclonal Ab to HIV-1 p24 antigen Current CDC adult HIV testing algorithm Quick reference guide for: Centers for Disease Control and Prevention and Association of Public Health Laboratories. Laboratory Testing for the Diagnosis of HIV Infection: Updated Recommendations. [stacks.cdc.gov/view/cdc/23447]. Published 6/27/2014. Current HIV EIA (4 th generation) Details The CDC-recommended HIV screening EIA should be a combination EIA that simultaneously detects: Patient antibody to HIV-1 Patient antibody to HIV-2 Presence of p24 antigen from HIV-1 A nonreactive test is reported as negative for HIV-1 antigen and HIV-1/HIV-2 antibodies 3

4 Current HIV Testing Details, continued Specimens with reactive results on the combination HIV immunoassay screening test must be confirmed by additional testing: HIV-1/HIV-2 antibody differentiation immunoassay If HIV-1 negative or indeterminate, perform HIV-1 nucleic acid testing (NAT) Interpretation of HIV algorithm testing results A reactive HIV-1 NAT result but nonreactive HIV-1 and HIV-2 antibody differentiation EIA indicates acute HIV-1 infection A reactive HIV-1 NAT result and indeterminate HIV-1/HIV-2 differentiation EIA indicates HIV-1 infection confirmed by NAT A negative HIV-1 NAT result and nonreactive OR indeterminate HIV-1/HIV-2 differentiation EIA indicates a false positive initial EIA As of October 2015, the following are FDA approved HIV screening combo assays Test Name Target analyte Assay format Abbott Architect HIV Ag/Ab Combo Assay (fully automated CLIA moderate assay) ADVIA Centaur HIV Ag/Ab Combo (CHIV) (fully automated CLIA moderate assay) BioPlex 2200 HIV Ag-Ab Bio-Rad GS HIV Combo Ag/Ab EIA (manual or semi-automated CLIA high complexity assay) HIV-1 p24 antigen and antibodies to HIV-1/2 Antibodies to HIV p24 Ag, HIV-1 including group O, and/or HIV-2 Simultaneously detects and reports: HIV Ag-Ab overall result with HIV-1 p24 Ag HIV-1 Ab (groups M & O) HIV-2 Ab HIV-1 p24 antigen and antibodies to HIV-1/2 Chemiluminescent microparticle immunoassay (CMIA) Chemiluminescent microparticle immunoassay (CMIA) Multiplex flow immunoassay Enzyme immunoassay micro-well format (EIA) As of October 2015, the following are FDA approved HIV supplementary assays Test Name Target analyte Assay format Geenius HIV 1/2 Supplemental System by Bio-Rad (CLIA moderate complexity) Multispot HIV-1/HIV-2 Rapid Test CLIA moderate complexity Aptima HIV-1 RNA Qualitative Assay (CLIA high complexity assay) Differentiates HIV-1 and HIV- 2 antibodies. Differentiates antibodies to HIV-1 and HIV-2, can be used as a screening test or as a supplemental test in a diagnostic algorithm HIV-1 Viral RNA Immunochromatographic. Assay results are read and interpreted by the Geenius Reader. ImmunoConcentration Transcription-mediated amplification of nucleic acid Advantages of 2014 CDC HIV Testing recommendations More accurate diagnosis of acute HIV-1 infection More accurate diagnosis of established HIV-1 and HIV-2 infection Fewer indeterminant test results Faster turn-around time for most tests employed Summary HIV diagnosis in adults and children >24 months utilizes 4 th generation assays Algorithm involves: initial screening EIA combo test (HIV-1/-2 IgM/IgG Ab + HIV-1 p24 Ag testing) If positive, followed by a confirmatory HIV-1/-2 differentiation EIA or possibly HIV-1 NAT 4

5 References 1. Quick Reference Guide Laboratory testing for the diagnosis of HIV infection: updated recommendations. Centers for Disease Control and Prevention; June 27, 2014; Parham, P The Immune System, 4 th Ed. Garland Science. ISBN: CDC: HIV Surveillance Epidemiology of HIV Infection (through 2014); 5

New HIV Tests and Algorithm: A change we can believe in

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