Performance of the HIV Blot 2.2, INNO-LIA HIV I/II and Geenius HIV 1/2 Confirmatory Assay for use in HIV confirmation

Penyampai:

Umar Amali Bin Abd Kadir

TML, PDN

Performance of the HIV Blot 2.2, INNO-LIA HIV I/II and Geenius HIV 1/2 Confirmatory Assay for use in HIV confirmation

Published: June 2018

Background

2014

The Centers for Disease Control and Prevention (CDC) in the United States (US) updated its recommendations for HIV confirmation - such that after an initial fourth-generation HIV Ag/Ab screening test, the use of HIV western blot was replaced by a HIV-1/HIV-2 antibody differentiation assay as the supplemental test for HIV confirmation.

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Background

2015

• HIV prevalence in the population tested is greater than 5%, a diagnosis of HIV-positive should be issued to individuals with 2 sequential reactive tests. Population tested is less than 5%, a diagnosis of HIV-positive should be issued to individuals with 3 sequential reactive tests.
• United Kingdom (UK) published by Public Health England (PHE) also recommended 2 separate reactive fourth-generation HIV Ag/Ab screening tests for HIV screening, followed by a HIV-1/HIV-2 antibody differentiation immunoassay.
• Australia, the Public Health Laboratory Network recommends that repeatedly reactive HIV antibody or antigen/antibody cases should be confirmed using a supplemental assay, inherently a western blot or a line probe immunoassay, with use of a nucleic acid or antigen test as necessary.
• In the revised recommendations from the US and UK, a HIV-1/HIV-2 differentiation assay has been included to allow diagnosis of HIV-2 infection as the virus has an intrinsic resistance to non-nucleoside reverse transcriptase inhibitors as well as to some protease inhibitors.

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Background

2016

Singapore has a low prevalence of HIV, with an exceedingly low prevalence of HIV-2. The latest national statistic shows that in 2016, 103.7 per million resident population were diagnosed with HIV infection. We use the triple test algorithm, as recommended by WHO and similar to Australia, which also has a low HIV-2 prevalence, the western blot is employed as one of the confirmatory tests. Specifically, we use the HIV Blot 2.2 Western Blot.

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Purpose of Study

In consideration of the recent recommendations for HIV-1/HIV-2 differentiation, a study was carried out to compare the performance of the:

• HIV Blot 2.2 Western Blot assay (MP-WB) to the
• INNO-LIA HIV I/II Score (INNO)
• and the Bio-Rad Geenius HIV 1/2 Confirmatory Assay (Geenius)

Material and Methods

1. The test panel consisted of 489 specimens.
2. Ethics review waiver (reason for waiver: research involves analysis of samples without identifiers) was given by the SingHealth Centralised Institutional Review Board.

Results

Results

Discussion

1. MP-WB was able to detect more early cases as indeterminate as mention in this article, however INNO and Geenius, were able to resolve those indeterminate cases.
2. Geenius may have an advantage over INNO because of its simpler and shorter test procedure.
3. The overall test sensitivity for early-stage infections was low for all 3 antibody-based assays, and nucleic acid or p24 antigen testing would probably be useful for diagnosis of such cases.

HIV in PDN

1. For over ten years, line immunoassay (INNOLIA HIV 1/2 Score) by Fujirebio was employed as a confirmatory testing for HIV antibody in Pusat Darah Negara.
2. World Health Organization (WHO) developed a Guidelines (Consolidated Guidelines on HIV Testing Services) in 2019 that recommends western blotting (WB) and LIA should not be used in HIV testing algorithms since it takes longer to provide the final HIV status to the client.
3. In 2022, Makmal Rujukan Kebangsaan (MRK) Pusat Darah Negara did evaluation on Bio-Rad Geenius HIV 1/2 Supplementary Assay as confirmatory test to replace INNOLIA HIV I/II score assay.

HIV in PDN

INNOLIA

• 16 hours incubation.
• Sample are pipetted by lab personnel into individual through in tray.
• Results are manually read by operator and verifiers, in comparison with digitally read scanned image.

Geenius

• Within 1 hour.
• Closed device for each sample (individual cassette).
• Results are digitally captured and image stored for easy traceability.

HIV in PDN

INNOLIA

Geenius

HIV in PDN

Total of 48 samples, representative of positive, negative and indeterminate INNOLIA HIV ½ Score results were used.

HIV in PDN

Conclusion

1. Geenius test is a safe and reliable alternative to other confirmation HIV test.
2. Geenius is simple and time-saving compared to INNO.
3. The detection of acute HIV infection is not the main issue in our lab since we are having NAT testing that perform concurrently with Serology screening.
4. Geenius decreased the number of final indeterminate HIV results.

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