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p24 antigen rapid test for diagnosis of acute pediatric HIV infection
Zaheer A Parpia1, Robert Elghanian, Arman Nabatiyan
1Department of Biomedical Engineering, Center for Innovation in Global Health Technologies, Northwestern University, Evanston, IL, USA.
Insights
A new, low-cost dipstick assay for detecting HIV p24 antigen in infants offers rapid, visual results. This point-of-care test is ideal for resource-limited settings, improving early diagnosis and treatment access.
Area of Science:
- Medical Diagnostics
- Public Health
- Biotechnology
Background:
- Limited-resource settings face challenges in diagnosing HIV in infants due to a lack of accessible, affordable point-of-care tests.
- Delayed diagnosis impedes timely initiation of antiretroviral therapy (ART) for HIV-infected infants.
Purpose of the Study:
- To develop a low-cost, visually read dipstick assay for detecting HIV p24 antigen in infants.
- To enable rapid and accurate HIV diagnosis in resource-poor settings.
Main Methods:
- Development of a heat shock methodology to optimize immune complex disruption in infant plasma.
- Analytical validation using recombinant p24 antigen and whole HIV-1 virus.
- Evaluation in archived and fresh infant samples from South Africa.
Main Results:
- The assay achieved analytical sensitivity of 50 pg/mL (p24 antigen) and detected as low as 42.5k RNA copies/mL plasma.
- In archived samples, sensitivity was 90% and specificity 100%.
- In field evaluations with fresh samples, sensitivity reached 95% and specificity 99%.
Conclusions:
- The dipstick p24 antigen assay is a simple, rapid (under 40 minutes), and cost-effective tool for infant HIV diagnosis.
- Minimal plasma volume (25 μL) is required, making it suitable for resource-limited environments.
- This assay can significantly improve early HIV detection and ART initiation in vulnerable populations.
Abstract:
Currently, the majority of HIV-infected infants are found within limited-resource settings, where inadequate screening for HIV due to the lack of access to simple and affordable point-of-care tests impedes implementation of antiretroviral therapy. Here we report development of a low-cost dipstick p24 antigen assay using a visual readout format that can facilitate the diagnosis of HIV for infants in resource-poor conditions. A heat shock methodology was developed to optimize disruption of immune complexes present in the plasma of infected infants. The analytical sensitivity of the assay using recombinant p24 antigen is 50 pg/mL (2 pM) with whole virus detection as low as 42.5k RNA copies per milliliter plasma. In a blinded study comprising 51 archived infant samples from the Women and Infants Transmission Study, our assay demonstrated an overall sensitivity and specificity of 90% and 100%, respectively. In field evaluations of 389 fresh samples from South African infants, a sensitivity of 95% and specificity of 99% was achieved. The assay is simple to perform, requires minimal plasma volume (25 μL), and yields a result in less than 40 minutes making it ideal for implementation in resource-limited settings.
