The Evolution of STI Testing: A Catalyst for Modern Diagnostic Technologies
HIV ASSAY DIAGNOSTIC TESTING EVOLUTION
ASSAY PROGRESSION
HIV-1 lysate Patient IgG Ab conjugate Signal
Ag conjugate Patient IgM
p24
HIV-2 lysate
HIV peptide
1985
1987
1991
1997
2015
YEAR
1ST GENERATION
2ND
3RD
4TH
5TH
ANTIGEN SOURCE
Virus-Infected Cell Lysate
Lysate & Recombinant
Recombinant & Synthetic Peptides
Recombinant & Synthetic Peptides
Recombinant & Synthetic Peptides
95-98%
>99%
>99.5%
99.5%
99.5%
SPECIFICITY
SENSITIVITY
99%
>99.5%
>99.5%
>99.8%
100%
NEGATIVE WINDOW
8-10WEEKS
4-6WEEKS
2-3WEEKS
2WEEKS
2WEEKS
DETECTED Ab & Ag
IgG & IgM Anti-HIV-1, HIV-2, Group O; also detects HIV-1 p24 Ag Separate HIV-1, HIV-2 Ab & Ag results
IgG & IgM Anti-HIV-1, HIV- 2, Group O; also detects HIV-1 p24 Ag Single result; does not differentiate Ab vs. Ag positivity HIV-1.2 differentiation assay, then qualitative HIV-1 RNA PCR if negative
IgG Anti-HIV-1
IgG Anti-HIV-1 & IgG Anti-HIV-2
IgG & IgM Anti-HIV-1, HIV-2, Group O
RESULTS
Single result
Single result
Single result
CONFIRMING TESTS
HIV-1 WB (Western blot) or IFA (immuno- fluorescence)
HIV-1 WB/IFA, HIV-2 ELISA & WB if HIV-1 confirm is negative
HIV-1 WB/IFA, HIV-2 ELISA & WB if HIV-1 confirm is negative
Not determined at the time of this writing
Figure 3. HIV Assay Diagnostic Testing Evolution Adapted from: Alexander, T. S. (2016). Human Immunodeficiency Virus Diagnostic Testing: 30 Years of Evolution. Clin Vaccine Immunol , 23 (4), 249-253. https://doi.org/10.1128/CVI.00053-16
beyond the clinic and making it one of the most patient-centered approaches to date. The OraQuick® In-Home HIV Test, approved by the US FDA in 2012, uses oral fluid to detect HIV antibodies, allowing individuals to test themselves privately without venipuncture. The INSTI® HIV Self Test, approved in 2025, further advanced this model by delivering highly accurate results in 60 seconds or less from a fingerstick blood sample.
Overall, self-testing assays are simple, fast and accessible—integrating streamlined workflows, intuitive digital instructions and, in some cases, telehealth connectivity for post-test counseling or confirmatory follow-up. This evolution represents a paradigm shift in HIV diagnostics, enhancing privacy, accessibility and testing frequency, particularly among populations deterred by stigma, cost or geographic barriers. 9
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