Detecting Small Amounts of Virus in Early Infections

High-pressure preconcentration devices for increasing the potency of biofluid samples to be used with point-of-care assays for detection of pathogens, such as flu or coronavirus. Courtesy of Amy Drexelius

Diagnostic devices that are used at home or in doctors' offices are often not sensitive enough to detect small amounts of a virus that might be present in samples from asymptomatic patients, which can occur in early stage COVID-19. In Biomicrofluidics, scientists report a membrane-based invention that can concentrate the virus content of a sample of urine or saliva, allowing it to be detected.

To increase sample concentration, previous groups have used gel particles, coupled to a chemical dye, to trap and detect a virus, but this approach is restricted to specific viruses that can bind to the dye. In addition, the testing time can be more than 30 minutes and requires expensive equipment.

Other approaches have been tried, but all lack the ability to diagnose different viruses or other biosubstances of interest, such as human chorionic gonadotropin, a hormone present in the urine during pregnancy.

Researchers at the University of Cincinnati and Wright-Patterson Air Force Base tried two different devices, both based on similar membrane-filter systems.

The first device was a fully integrated concentration unit coupled with a component that could detect the virus in question. A vacuum was used to pull water through the membrane, leaving behind the virus in a more concentrated solution, and the sample was analyzed in the same device.

"The amount of time needed to complete the concentration process was very slow," said author Amy Drexelius. "On average, each device took about 30 minutes to complete the concentration process. We, therefore, concluded that the vacuum driven auto-staging device is not practically useful and turned to an alternate device utilizing a much higher positive pressure."

The second device was considered because the investigators realized that by applying high pressure, instead of high vacuum, they could increase the pressure differential between the sample and the surroundings. A nitrogen gas tank and regulator were attached to their second device, allowing the application of up to 100 pounds per square inch of pressure.

The group investigated real biofluids, saliva and urine, spiked with samples of protein from influenza A virus. Other samples contained HCG.

"The test results were extremely consistent with the second device, showing a concentration result of 33 times that of the original sample," said Drexelius. "Preconcentration of a 1-milliliter sample could be achieved in five minutes or even faster with higher applied pressures."

The novel coronavirus that causes COVID-19 was not tested, but the method should work for it, since the technology could successfully detect influenza A. Both are respiratory viruses likely to be present in saliva. The technique is, in addition, promising for pregnancy testing, where early results are also highly desirable.

The article, "Analysis of pressure-driven membrane preconcentration for point-of-care assays," is authored by Amy Drexelius, Anna Hoellrich, Andrew Jajack, Eliot Gomez, Michael Brothers, Saber Hussain, Steve S. Kim, and Jason Heikenfeld. The article will appear in Biomicrofluidics on Sept. 1, 2020 at

5 Comments on "Detecting Small Amounts of Virus in Early Infections"

  1. 979332 748155Great post man, keep the nice function, just shared this with my friendz 140488

  2. 813722 795305Hi there, just became aware of your weblog through Google, and located that its truly informative. Im gonna watch out for brussels. Ill be grateful if you continue this in future. Several people is going to be benefited from your writing. Cheers! 700752

  3. 341405 997911As I website owner I believe the articles here is actually great , thankyou for your efforts. 628579

  4. 606991 234956A genuinely fascinating read, I may nicely not agree totally, but you do make some quite legitimate factors. 542930

  5. 251311 713197Have read a couple of of the articles on your site now, and I genuinely like your style of blogging. I added it to my favorites weblog site list and will probably be checking back soon. 391980

Leave a comment

Your email address will not be published.