March 2022, ScientificAmerican.com 45urally occurring DNA, which is right-
handed—so they do not interfere with
the detection process. By adding a spe-
cific amount of the left-handed DNA
and tracking how much of it is copied,
Adams can use it as a benchmark to calibrate and confirm that the
PCR machine is running without worrying about many impurities.
Adams says that by reducing the need for purification with the left-
handed DNA—which costs about 11 cents per test—labs could save
significant labor and material costs.
Now that COVID has shown how important it is for testing to
be accessible, there is more enthusiasm for portable PCR devices.
Avleo Technologies has designed a handheld molecular testing
machine that gives results in 30 minutes. Another device, from
Visby Medical, was initially developed to look for sexually trans-
mitted infections such as chlamydia and gonorrhea (and received
fda clearance for those applications) and has since added testing
for SARS-CoV-2. Anavasi Diagnostics’ AscencioDx platform, orig-
inally developed to detect HIV and flu before the pandemic hit, is
being used in trials as a rapid molecular COVID test. In November
2021 the National Institutes of Health awarded $14.9 million to
Anavasi to support that initiative.
Diagnostics developers are continuing to tinker with PCR. Ger-
man engineering company Solarkiosk Solutions is developing a
version that runs on solar power, which it is piloting for COVID
testing in a remote part of Sumatra where many residents lack
access to electricity and diagnostics. Academic labs and start-ups
such as Mammoth Biosciences in San Francisco are combining tra-
ditional PCR methods with CRISPR gene-editing technology to
make the tests more efficient at detect-
ing specific pathogen genes.
At Uganda’s border crossings, Ssen-
gooba says that testing, at this moment,
anyway, is “very smooth.” But nearly
40 years after the idea of PCR was born, the technology is evolving
rapidly as a result of the pandemic, and Ssengooba is dreaming big.
He is eager to try the handheld disease diagnostics because tradi-
tional PCR—including the printer-size machines at the border—
still require hookups to the electricity grid and various sample-pro-
cessing rooms. A portable version, akin to the one in development
by Indian company Molbio, could bypass some of these require-
ments and open up fast-testing access to remote areas for the first
time. “This is something that is incredible,” he says.
Public health has always been stymied by the hours or days
between collecting a sample and delivering the results to the
patient; in the meantime, an infected person has left the clinic and
gone back to the routines of their life, unwittingly exposing others
and delaying treatments that are often more effective if started ear-
lier. COVID, and the stunning transmissibility of Omicron in par-
ticular, has laid bare the consequences of that gap—for individual
health, community transmission, overburdened hospitals, labor
shortages, and so much more. Ssengooba is hopeful that the
urgency for closing that gap will persist. When imagining a future
where portable PCR tests with on-site results are commonplace,
“all of these challenges,” he says, “are going to be left behind.”Roxanne Khamsi is a science journalist and radio contributor based in Montreal.
She has reported extensively on the COVID pandemic.UNASSUMING MACHINES: GeneXpert mod-
ules use PCR technology to test for all kinds of
infectious diseases, including COVID.