A new rapid antigen test technology developed by scientists in Singapore that tests for the SARS-CoV-2 virus is able to produces results in minutes, without the need for additional equipment or specially-trained personnel.

Scientists dubbed the technology the Parallel Amplified Saliva rapid Point-of-Care Test—also known as PASPORT. Using a proprietary on-kit amplification technique, a person’s saliva can be self-administered or tested for the SARS-CoV-2 virus at the point-of-care with sensitivity higher than current rapid antigen tests and close to that of laboratory-based polymerase chain reaction (PCR) tests.

The invention was borne out of a research collaboration between Duke-NUS Medical School, Singapore General Hospital (SGH) and National Cancer Centre, Singapore (NCCS)—collectively member institutes of the SingHealth Duke-NUS Academic Medical Centre—and the National University of Singapore (NUS).

A test that can be done on-site will enable doctors to diagnose COVID-19 accurately and prescribe the drugs appropriately. Moreover, with its anticipated low cost and ease of use as compared to PCR tests, PASPORT could aid Singapore and countries around the world in making early diagnosis of COVID-19 to initiate appropriate case management.

“Like COVID-19 vaccines, the availability of oral anitiviral drugs will be another game changer in our fight against COVID-19. But these drugs will need to be given as early as possible after illness onset for maximal benefit. A test that can be self-administered or used on-site at the primary care setting may mitigate the need for cases to be managed at the hospitals,” says Ooi Eng Eong, PhD, MD, from the Duke-NUS EID Programme, who is one of the senior co-inventors.

The research was published online in the journal Microchimica Acta as a feature article in their series, ‘From Bench to Hand’.

“Testing is an indispensable tool in the management of COVID-19 cases. Although PCR has been the gold standard, it requires trained personnel and laboratory infrastructure,” says lead inventor Danny Jian Hang Tng, MD, Medical Officer at the Department of Infectious Diseases, SGH, and an adjunct Research Fellow at Duke-NUS’ Emerging Infectious Diseases (EID) Program.

Unlike tests that use nasal or throat swabs, saliva-based tests are convenient and are more easily self-administered. But, until now, saliva tests for detecting SARS-CoV-2 have not been considered reliable enough to roll out at large scale. This is because the concentration of viral particles in saliva drops steeply after an individual eats or drinks. As a result, saliva antigen tests are usually only reliable when they are performed first thing in the morning, after an overnight fast and before breakfast or brushing teeth. This makes testing of saliva samples at other times of the day less reliable.

The researchers remedied this by using a two-stage process. Like other rapid antigen tests, PASPORT uses nanoparticles to bind the virus. But it also adds a second type of nanoparticle that binds the first set of nanoparticles to amplify the signal. This makes testing using PASPORT more sensitive at finding and flagging the virus.

In a clinical study involving over 100 participants conducted at SGH, PASPORT’s sensitivity in detecting the virus was 97 percent and its specificity, 90.6 percent, compared to the gold standard PCR test.

Duke-NUS and SingHealth have filed intellectual property protection for the invention, and have entered into a license agreement with Digital Life Line Pte Ltd, a Singapore-based company. The inventors hope that through close collaboration with commercial partners, the product can be out in the market as soon as possible to serve healthcare needs in Singapore and beyond.

“Our invention ticks all the boxes for an ideal rapid test: ease of collection of saliva; highly accurate with very low false negative results, making it an invaluable screening tool; and can be done at any time of the day, making it possible to be used at point of care, with reliable authentication. With this, we hope that more people will do the test as a personal act of social responsibility before engaging, especially, in large-scale events or gatherings,” says Soo Khee Chee, MBBS, MD, FRACS, FAMS, FACS, Benjamin Sheares Professor in Academic Medicine at the SingHealth Duke-NUS Oncology Academic Clinical Program, a Senior Advisor to Duke-NUS, and a senior co-inventor.

The development of the PASPORT prototype was partially supported by the Estate of Tan Sri Khoo Teck Phuat, of the Khoo Foundation, Singapore.

Featured image: PASPORT, a new saliva-based COVID-19 ART test, is easy to self-administer, deliver results in minutes, and has sensitivity close to the gold standard PCR test. Photo: Duke-NUS Medical School