A Single-Molecule Digital Immunoassay Identifies HIV in Blood

A single-molecule digital immunoassay can be used to identify acute Human immunodeficiency virus (HIV) infection in blood as early as the most sensitive and costly nucleic acid testing (NAT) techniques.

Dubbed Simoa, the single-molecule digital immunoassay for HIV detection achieved results with 3,000 times greater analytical sensitivity than conventional immunoassays. Simoa's sensitivity is comparable to the more costly gold standard of nucleic acid testing (NAT). Using Simoa technology individual molecules of p24 capsid protein (a component of HIV virus particles) are counted in blood, indicating the presence of HIV virus.

Quanterix (Lexington, MA, USA) developed the Simoa platform, which uses single molecule measurements to access previously undetectable proteins. With this sensitivity and full automation, Simoa offers benefits to both research and clinical testing applications.

The study was published online in the Journal of Virological Methods, in October 2012. "In the first days and weeks following HIV infection, a patient is particularly contagious as the virus multiplies rapidly before the onset of an immune response," explained David Wilson, PhD, vice president of product development at Quanterix and the paper's lead author. "The earliest detection possible during this acute phase is critical for controlling the spread of the disease, as well as ensuring blood donated by recently infected individuals does not enter the blood supply. Until now, NAT was the most sensitive method for early acute HIV detection, but its use is cost prohibitive for routine HIV screening, particularly in lower resource settings. Our data indicate that acute HIV infection can be detected with a simple, low-cost Simoa digital immunoassay as early as NAT methods."

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