Test Designed to Detect Equine Disease Shows Promise for COVID-19
Smartphone technology constantly improves, with each new phone touting coveted camera enhancements such as number of megapixels, fast autofocus, and better low-light performance. Those same companies can now add “infectious disease detection” to their lists of camera features. Researchers have discovered a way to use a phone’s camera to detect viruses that cause respiratory diseases such as equine influenza and COVID-19 in humans.

“As we have recently witnessed, upper-respiratory diseases can rip through communities quickly, leaving a wake of death, illness, economic losses, and major disruptions to daily life,” said Brian Cunningham, an electrical and computer engineering professor at the University of Illinois at Urbana-Champaign.

One of the major contributors to the rapid spread of upper-respiratory infectious diseases such as COVID-19 in people is the lack of widely available testing that provides quick and accurate results. As such, communities can’t make informed recommendations pertaining to targeted quarantines to best control the spread of disease.

Similar disease outbreaks occur in horses—recall the 2011 equine herpesvirus-1 (EHV-1) outbreak involving 240-plus horse premises in 19 states and two Canadian provinces.

“The key to infectious disease surveillance and control regardless of the affected species is early stage diagnosis,” Cunningham said. “The problem for many infectious diseases is that it takes time to send the test to the lab and have it processed, taking into consideration weekend/holiday hours and backlog of samples.”

Further, many upper-respiratory diseases can present with similar clinical signs, and some patients can be co-infected with more than one pathogen (e.g., equine influenza and EHV-1). Having to test for more than one disease to achieve a definitive diagnosis also delays appropriate control strategies.

“Given the downside of conventional testing protocols for infectious respiratory conditions, novel means of testing for one or more infectious diseases simultaneously that provide rapid, inexpensive, portable, point-of-care results would be advantageous,” Cunningham said.

Cunningham’s research focuses on the development of novel devices and instrumentation for life sciences. In collaboration with equine veterinarian David Nash, DVM; molecular biologist David Hirshberg, PhD, of the University of Washington; and bioengineer Rashid Bashir, PhD, at the University of Illinois, his group developed a novel testing technique for an array of respiratory pathogens affecting horses. Pathogens included Streptococcus equi subspecies equi and zooepidemicus, EHV-1 and -4, and equine influenza.

The test detects viral RNA (genetic material similar to DNA) obtained directly from nasal swabs. The RNA on those swabs is converted to DNA and then amplified in liquid compartments inside a silicon chip. This chemical reaction is called “loop-mediated isothermal amplification” and can generate billions of copies of the original viral nucleic acid sequence in just 30 minutes. During amplification fluorescent markers bind to target sections of DNA copies that smartphone cameras can subsequently detect as green light.

Other compartments within the same silicon chip can perform separate tests that distinguish between different viruses. This means it can test for multiple pathogens simultaneously. Appropriate use of positive and negative controls reduces the likelihood of false positive and negative results.

In sum, veterinarians can use the test to identify several infectious respiratory-disease-causing viruses in about 30 minutes while still at the patient’s side using a smartphone and a chip roughly the size of the phones’ SIM cards.

While the test brings great news for the equine industry, Cunningham noted that “our efforts are motivated by the urgent need to develop rapid point-of-care testing for highly contagious human respiratory viruses such as COVID-19.”

If the test takes off, it would immediately fill a cavernous void in controlling infectious disease spread in horses, humans, or any animal species, he said.

The article, “Smartphone-based multiplex 30-minute nucleic acid test of live virus from nasal swab extract” was published in the May 2020 edition of the journal Lab on a Chip.