US researchers develop PEDV antibody test

Veterinary researchers at Iowa State University have developed a new test to detect antibodies against Porcine Epidemic Diarrhoea Virus (PEDV), a costly disease in pigs confirmed in the United States for the first time this year.

Previously, the virus could be detected only in acute cases while it was still reproducing and infecting a host pig. In such cases, the virus could be identified through the use of a test known as a polymerase chain reaction assay. But those tests could give a false negative if the pig had stopped shedding the disease or if shedding had become intermittent.

The new test, called an immunofluorescence antibody or indirect fluorescent antibody assay and conducted using blood samples from pigs, will allow vets and producers to know if a pig has ever had the disease in the past, and whether it’s shedding the virus or not.

It’s the first test available to the US veterinary community that can detect PEDV antibodies.

“The new test gives practitioners and their clients a historical perspective,” said Dr John Johnson, a clinician in veterinary diagnostic and production animal medicine. “It’ll help them to understand if a particular animal has been exposed to the virus before. This tool, coupled with polymerase chain reaction results, will provide additional crucial information as veterinarians and their clientele assess the risk of moving a group of animals into a PEDV-negative population.”

Dr Kyoung-Jin Yoon, a professor of veterinary diagnostic and production animal medicine, led the effort in developing the new test. He said the screening works by detecting the presence of PEDV antibodies in a blood sample. If the antibodies are present, then the pig in question has been exposed to the virus before.

The screening, available through the Iowa State University Veterinary Diagnostic Laboratory, costs $5.50 (£3.50) per sample and can be requested by local vets.

“In order for this test to function, we must first have an isolated virus on hand,” Dr Yoon added. “For a long time, it’s been difficult to isolate the virus in a cell culture, so there are a lot of tricks and manipulation we have to do to make this virus propagate in cell culture.”

The test will be especially helpful to pork producers who are looking for replacement breeding stock, Dr Johnson said. By performing the test, producers can know if an animal has been exposed to the virus in the past before they bring it onto their farms.

The Iowa State University Veterinary Diagnostic Laboratory identified the first US cases of PEDV in early May. Since then, the diagnostic laboratory has helped to confirm cases of the disease in 17 states, including Iowa.

Diagnosticians and clinicians in the ISU Department of Veterinary Diagnostic and Production Animal Medicine and the Iowa Pork Industry Center are now working closely with producers and veterinarians to implement best practices to diagnose the disease in other herds and to minimize its impact and prevent its spread to uninfected herds.

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