HIV 4 th Generation Testing for the Diagnosis of HIV Infections

Transcription

1 HIV 4 th Generation Testing for the Diagnosis of HIV Infections John J. Rushton, PhD, MBA PAML Science, Technology and Innovation Director May 19, 2015 Welcome Your Host: Karen Riba Handout is available by highlighting the file in the File Transfer dialogue box and clicking on the download button. If the box is not visible click on File, Transfer and follow the steps above. For technical difficulties please kchandler@paml.com. For questions you have during the presentation use the Q & A panel in the lower right hand corner of your screen. Type your question in the box and click Send. Questions will be answered at the end of the presentation This presentation is not to be copied or distributed without the specific permission of PAML LLC Welcome P.A.C.E. credit may be obtained by submitting your completed evaluation form at the end of the webinar Evaluation is available in the File, Transfer box. PAML employees will be able to receive one hour of continuing education. This presentation is not to be copied or distributed without the specific permission of PAML LLC 1

2 John Rushton, PhD, MBA Speaker Image PAML Science, Technology and Innovation Director Dr. Rushton provides scientific advice, technical guidance, and leadership support to PAML, LLC, and PAML Ventures. This includes evaluating new testing, technologies and instrumentation as PAML expands its footprint and testing options. This presentation is not to be copied or distributed without the specific permission of PAML LLC Objectives Define the new CDC recommendations on HIV testing Recognize the differences between 3rd and 4 th generation HIV testing Describe confirmatory and differential testing for HIV Discuss the recommended testing algorithm Background HIV - Human Immunodeficiency Virus HIV positive does not mean a person has AIDS HIV attacks CD4 cells and the infection is generally considered to be permanent AIDS - Acquired Immunodeficiency Syndrome AIDS is marked Drop in CD4 cell levels Rare opportunistic infections 2

3 HIV History and Jump SIV Jumps to human Documented Death in Congo AIDS identified in Drug user and HAART gay male communities Maybe in HIV screening U.S. Enters U.S. Virus identified HIV4th gen screening Late 1800 s s Patient 1970s 1981, June In 1966? Number of New HIV Infections 2013 HIV Affects All Races and Ethnicities 3

4 HIV Infections by State New Diagnosis HIV Infections Why Get Tested CDC HIV Treatment Antiviral treatments have progressed Prior to 1990 s, most HIV infected individuals progressed to AIDS in a few years Today the early detection means therapy can begin before progression to AIDS Individuals can live a normal life span with Anti-Retroviral Therapy (ART) 4

5 Anti Retroviral Therapies Extending Life Where Does 4 th Generation Testing Fit? Early Detection Important in public health context Key to know status Early identification of patients can limit spread Positive individuals are reported to the state health agency for follow up and communication with sexual partners Earlier detection means earlier access to therapy Coupled with education programs most advantageous to stopping spread 5

6 Stages of HIV Infections Primary Infection Virus contracted Acute Infection Early stage of infection when virus replicates and immunity mounts Clinical Latency Body keeps virus in check ART maintains AIDS (Acquired Immunodeficiency Syndrome) Acute Infections (Acute Retrovirus Syndrome) 2-4 weeks of exposure symptoms appear similar to flu. Virus replicates in CD4 cells. Large amounts of virus produced. Individual is most infectious. Body mounts an immune response. Some individuals don t develop this phase. Viral infection can be controlled to a level by immune response and viral load will drop and CD4 levels may increase. May not test positive at this stage. Clinical Latency Generally asymptomatic Chronic infection Virus replication is at low levels and is controlled by body Can last for up to 10 years untreated Can be in this phase for decades with Antiretroviral therapy Can still transmit but at lower risk of transmission At end of this phase Viral levels rise and CD4 cell levels drop 6

7 AIDS (Acquired Immunodeficiency Syndrome) This is the final stage of an HIV infection Immune system badly damaged Become vulnerable to opportunistic infections Kaposi s sarcoma, Histoplasmosis CD4 levels fall below 200 cells per ml Normal levels are cells per ml Three years life expectancy at this point if untreated Years After Infection HIV Screening Protocols 7

8 History HIV Screening Tests HIV 1 st generation Viral lysates for detection of IgG antibodies to HIV1 HIV 2 nd Generation Synthetic Antigen to detects IgG antibodies to HIV1 HIV 3 rd Generation HIV antibodies detected Western blot for HIV1 HIV 4 th Generation Combo assay for p24 and HIV antibodies Multispot differential analysis of HIV1 and HIV2 Recommended CDC 4 th Generation Testing HIV 3 rd vs. 4 th Generation Testing 3 rd Generation IgG and IGM detected May miss acute infection Must sero convert Confirmation Western blot for confirmation Only detects HIV1 4 th Generation IgG, IgM and HIV p24 Earlier detection window Do not need to sero convert Confirmation Multispot confirmation Differentiate HIV1 and HIV2 8

9 Rapid HIV Screening Pros Done in clinic Sensitivity and specificity is very good (95%) Oral HIV tests may not correlate as well with Western blot May need a serum based assay with discrepant results Good when patient likely not to come back Cons Requires trained staff Requires monitoring quality Expiration risk Inappropriate storage risk Need to coordinate confirmatory testing Need a procedure for public health reporting Western Blotting Confirmation Positive: At least TWO of the major bands: (gp 160, gp 120), gp 41, or p24 must be present. Indeterminate: One or more bands are present, but the blot does not meet the positive requirements. Presence of gp160 or gp120 without the other bands Negative: no bands present Intensity can be at play here Subjectivity because must be as intense as LPC Not automatable Western Blot Subjectivity At least TWO of the major bands: gp 160, gp 120, gp 41, or p24 must be present. Bands must be at least as intense as the LPC gp 120 band (i.e., a relative score of +) to be considered as positive. The bands at gp 41 and gp 120 must be broad and diffuse. The presence of gp 160 and/or gp 120 gp qualifies as one major band when determining if at least two of the major bands are present. Take care not to confuse the gp 41 band with the sharp narrow band at p40. 9

10 Multispot HIV Differentiation Clear results Rapid TAT three days HIV1 and HIV2 tested Simple methodology No extra specimen required Multispot vs. Western Blot Clear result Fast 3 day TAT Improved sensitivity Early detection in acute phase of infection Measures IgG and IgM antibodies Differentiates HIV1 from HIV2 Result can be subjective 7-10 day TAT Lower sensitivity Delayed detection Only detects IgG Miss acute phase infections Can only detect HIV1 Performance Summary 10

11 Additional Support Testing Confirmatory HIV Nucleic Acid Amplification Testing (HIVUS) PCR based assay Detects copies per ml of plasma Not meant for primary screening Requirement of second sample collection Concern for carry over on immunoassay equipment HIV Genotyping (HIVGT3) Used for therapy selection Monitor sustained virologic response Monitor evolution of HIV infection HIV carries many mutant forms Drug regimens can select for different genotypes Monitor therapy success Monitor therapy compliance 11

12 HIV Testing Summary HIV4GM EIA screening Combo assay for earlier detection compared to 3 rd generation testing HIVDF Multispot offers superior sensitivity and TAT to Western blot HIVUS Confirmatory testing for indeterminate results HIVGT3 Genotyping assay for treatment decisions Thank You for Attending P.A.C.E. credit may be obtained by submitting your completed evaluation form. You will find the form by clicking on File, Transfer and downloading the evaluation PAML employees will be able to receive one hour of continuing education credit by submitting your attendance through CE Manager. This presentation is not to be copied or distributed without the specific permission of PAML LLC Thank You for Attending We will be leaving the webinar open for 15 minutes to allow you to download the handouts This webinar has been recorded and will be available by Tuesday, May 26 th, at PAML s next webinar is scheduled for September 8 th, 12:30 p.m. 1:30 p.m. (PT) Please send ideas for future webinar topics This presentation is not to be copied or distributed without the specific permission of PAML LLC 12