HIV Testing Technologies

Katrien Fransen (ITM) BREACH symposium Breack out session 28/29 September 2012

Topics • • • • •

3rd and 4th generation screening tests Window period (time delay for testing) New: specimen, SRT, home testing… Quality assurance programme of SRT Preliminary conclusions/recommendations

HIV antibody testing for HIV diagnosis Screening test (EIA) and confirmation test (western blot or LIA) + control - + ++

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FLOW CHART ARL HIV CONFIRMATIE STRATEGIE

monsters doorgestuurd voor confirmatie

EIA1 / EIA2 EIA1 EIA2 -

EIA1 + EIA2 +

Ag

LIA

Ag +

Ag -

LIA HIV1 + HIV2 -

EIA’s discordant

LIA HIV1 HIV2 +

LIA HIV +

LIA HIV Ind

LIA HIV1 HIV2 -

Ag

Ag

1 Mogelijk seroconversi e: 2de staal vragen

Negatief

HIV 1 positief

WB2

HIV 2 positief

Vervolg pagina 2

WB2 +

WB2 -

WB2 ind

Ag +

Ag -

Ag +

Ag -

HIV pos 10ml EDTA bloed voor differentiatie PCR

HIV 1 positief

Mogelijk kruisreactie : staal voor PCR vragen

Mogelijk seroconversi e: 2de staal vragen

Onbepaald resultaat: 2de staal vragen

Mogelijk seroconversi e: 2de staal vragen

Negatief

Vervolg pagina 1

LIA + Ag

LIA HIV ind Ag -

LIA HIV ind Ag +

LIA HIV Ag -

LIA HIV Ag +

LIA HIV1 + Ag -

LIA HIV1 + Ag +

LIA HIV2 + Ag -

LIA HIV2 + Ag +

Onbepaald resultaat 2de staal vragen

Mogelijke seroconversi e 2de staal vragen

Negatief

Mogelijke seroconversi e 2de staal vragen

HIV 1 positief

HIV 1 positief

HIV 2 positief

HIV 2 positief

LIA HIV + Ag -

LIA HIV + Ag +

WB2

1

Legende EIA1 = Enzygnost Anti-HIV 1/2 Plus EIA2 = Vironostika HIV Uni-Form II Ag/Ab LIA = INNO-LIA HIV I/II Score Ag = INNOTEST HIV Antigen mAb WB2 = NEW LAV BLOT II

Verklaringen EIA’s discordant = EIA1+ / EIA2 - of EIA1 - / EIA2 + LIA HIV Ind = LIA HIV1 ind of LIA HIV2 ind of LIA HIV1 /HIV2 ind

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Enzyme linked immunosorbent assays (ELISA)

1st generation Purified HIV lysates

sensitivity increase

2nd generation Recombinant proteins and/or synthetic peptides

3rd generation or sandwich ELISA’s Labelled antigen as conjugate 4th generation or DUO assays Detect Ag and Ab without differentiation 5th generation or DUO assays Detect Ag and Ab with differentiation

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Seroconversion panels • Commercial: subtype B, variable bleeding time points of each of the panel members Time between detection of RNA and Ag test: Time between detection of RNA and 4th generation test: Time between detection of RNA and 3rd generation test:

0-12 days 0-18 days 0-26 days

• Clinical trial ‘Prep’ panels: non-B subtypes, fixed time points (4 weeks). Unpublished data. Time between detection of RNA and Ag, 4th, 3rd generation test: 0-4 weeks or 28 days

Belgian guidelines (update 2011) • https://www.wiv-isp.be/epidemio/arl -Serological test 4-8 weeks after suspected contact, repeat after 3 months and for medicolegal reasons after 6 months (prof exposure). If primary infection is suspected, perform the test immidiately and inform the laboratory.

Pro for keeping the 3 months. - Not many studies, data to answer that question (prep studies) (recomm) - 20% of the periferal laboratories are still not using 4th generation test (recomm)

- Analytical sensitivity of the p24 Ag varies (11-160 pg/ml), no HIV 2 - Not all the patients are telling the thruth about risk and time of the risk Risk perception is not well known (recomm) - The laboratory is not allways informed about the recent risk and therefore an Ag test is not performed or asked (recomm) - Literature, on late seroconverters, second window period

Conclusion: a test performed 3 months later will cover the missed diagnosis. Nevertheless according to the preliminary data of the seroconverters (subtype B and non B), we can assume that most of the hiv infections (99%?) will be detected within the period of 4-6 weeks after risk exposure. (if no ARV was taken)

 Alternatives: Simple rapid tests - More than 100 different assays (WHO procurement list). Agglutination assays, Immunofiltration assays (flow through), Immunochromatographic assays (lateral flow through), Dipsticks. - Very few 4th generation tests (CE label): 1) DetermineTM HIV-1/2 Combo (Alere), 2) SD BiolineTM HIV Ag/Ab Combo test (Standard diagnostics) Attention: different sensitivities of the performance of the Ag (analytical, subtype and type specific). Is not well covered by the CE label, nor by the WHO panel. Additional evaluations/validations are needed. 11

 Alternatives: Oral fluid tests (no Ag) - SRT (CE, FDA): OraQuick Advance Rapid HIV-1/2 Cons: expensive (40$), 3rd generation, variable in quality ? (NY), IQC and EQC ? - ELISA: Genscreen, Vironostika, Enzygnost Oracol device to collect oral fluid, followed by an adapted protocol and cut-off calulation for screening.

Broaden the reach of testing programs: outreach testing, epidemiological and surveillance studies 12

 Alternatives: Home testing, self testing Pro Autonomy, less risks if status is known… Cons Expensive, no proved, consistant quality, obscure companies, no CE label, ethical issues, link with care (for counseling and treatment)? But… will be (is) used and we have to do more research on the usefulness of those tests especially in broadening the acces of people being tested. 13

EQC for SRT and OF tests • Serum/plasma: existing EQC programmes (HIV ab/ag) • Whole blood, capilary blood, oral fluid, saliva (urine): no existing EQC programmes. Organise an EQC using spiked serum in negative whole blood or negative oral fluid. Make a dilution series and use a week positive sample for lot control and/or internal control. Ask informed consent of the negative donors and mix several donors. A EQC can be prepared in the same way (blind).

Recommendation/conclusion -4th generation screening test mandatory,

-be aware of the existance of an Ag test -ARL guidelines 4-6 weeks, 3 months but develop a tool for self risk assesment -SRT and saliva test: reach vulnerable people, broadens access to HIV test. -self test, home test, home sampling: is used allready, expensive, questionable quality, best to have a link with an ARL for quality control and further testing and with an ARC for care for prevention and treatment. -> research