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Investigating the new test that detects African swine fever in 20 minutes

The Pig Site speaks to the Vice President of Sales & Business Development at Silver Lake Research Corporation, the company that makes and manufactures the only low-cost rapid African swine fever test in the world with accuracy rates greater than 95 percent.

6 March 2020, at 9:00am

Silver Lake Research Corporation makes and manufactures PenCheckTM, the only low-cost rapid African swine fever test in the world with accuracy rates greater than 95 percent. The research group is in the business of developing monoclonal antibodies to detect a variety of environmental, veterinary or clinical targets. What they have done with PenCheckTM is develop a set of monoclonal antibodies to detect a very specific viral protein that is expressed by the ASF virus currently spreading through pig populations in Asia and Europe.

This week, The Pig Site speaks to Erik Serrao, Vice President of Sales & Business Development at Silver Lake Research Corporation, who tells us more about the development of this new rapid test, and why it’s invention will be critical to preventing the spread of this highly contagious virus.

“Once we developed the specific ASF antibody in the lab, we very quickly engineered a rapid dip-stick style test that can detect this viral protein and in effect, detect this virus in whole blood of pigs within 20 minutes,” explains Serrao.

“We have a variety of products that have the same structure – a simple, inexpensive dip-stick test – which all use monoclonal antibodies, which means they are all extremely specific and sensitive to their targets.”

The sensitivity of this test is essential to its success at identifying the ASF virus as quickly as possible.

The pig only begins to show moderate to severe clinical signs after around four days – approximately halfway into the viral cycle so by the time the pig is visually detected to be showing clinical signs of ASF, it has probably already infected every other pig around. It is therefore easy to understand how this virus can spread and kill an entire herd very quickly.

“The ideal diagnostic method needs to be quick in order to identify and remove infected pigs from the herd and quarantine them as quickly as possible,” says Serrao.

The PenCheckTM test requires no specialist training to use and produces results in 20 minutes, making it a significantly faster way to identify infected and non-infected animals.

blood sample

Serrao says that the test is so fast and simple, he can describe the entire procedure in under 30 seconds.

  1. Withdraw a small amount of blood – a common procedure carried out by producers – from the ear or tail.
  2. Pipette this small amount of blood into the provided test tube and add a small volume of water. Serrao stipulates that the water used for testing these blood samples should be distilled, or bottled, or at least safe drinking water.
  3. Insert the test strip into the mixture.
  4. Read the result in 20 mins.

The current gold standard for detecting African swine fever that is used in the field right now is quantitative PCR. Using PCR requires training and liquid reagents, and it can take up to ten hours to get results. Conducting PCR is also expensive, and it can’t generally be used to test a lot of samples at the same time.

“PenCheckTM is projected to be around five times cheaper than quantitative PCR and produces an accurate result in 20 minutes rather than 6-10 hours,” says Serrao.

“It is also amenable to multi-plexing – testing multiple samples at once – so you can test an entire herd in very little time.”

The product is in the early stages of being marketed across affected regions of Asia and Europe, and Silver Lake Research is actively seeking distribution partners to navigate regulatory and other licensing requirements in all affected Asian and European countries. Serrao says that there are other tests flooding the market that are not so accurate so people are rightfully very cautious about using a new method. This said, he’d like to emphasise the data that Dr Juergen Richt at Kansas State University has put together.

Dr Richt, DVM, PhD, conducted an independent clinical validation study to determine the accuracy of PenCheckTM. The sensitivity of PenCheckTM test was 95.5 percent, with a specificity of 99.3 percent. In the sensitivity tests, PenCheckTM correctly identified 21 out of 22 pigs with moderate to severe symptoms of African swine fever. In the specificity tests, PenCheckTM was found to be very dependable. In 144 pigs with no prior symptoms, PenCheckTM correctly determined 143 pigs did not carry the virus.

“The test is highly accurate,” concludes Serrao.

“There are no other rapid tests in the world to detect ASFv with this level of validated field accuracy.

“I can confidently say it’s the most sensitive and specific rapid ASF screening test in the world.”