In 2013, a sample from a pig in Indiana tested positive for porcine epidemic diarrhea virus, the first discovery of the virus in North America. Today, it has spread to 32 states — including Virginia — and resulted in at least 10 million piglet deaths, according to the latest figures from the U.S. Department of Agriculture.
A researcher at the Virginia-Maryland College of Veterinary Medicine at Virginia Tech is hoping to create a more effective vaccine against this newly emergent but economically devastating virus plaguing the U.S. pork industry. Adam Rogers, a postdoctoral associate in the Department of Biomedical Sciences and Pathobiology, has received a two-year, $150,000 grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture to take the first steps toward a new vaccine.
“The process starts in the laboratory here using molecular techniques to make genetic changes to the virus and test it in small-scale tissue cultures in the laboratory. If we find a mutation or mutations that will make the virus non-pathogenic, then we will move onto an animal test,” said Rogers, who earned a Ph.D. in microbiology and virology at the University of Nebraska before coming to Virginia Tech in 2013. “We are starting with the emergent American strain of the virus so that we will end up designing a vaccine specifically targeted to control the disease here.”
Rogers’ mentor X.J. Meng, University Distinguished Professor of Molecular Virology, explained that even though the researchers were using the emergent U.S. virus strain, a new vaccine based on the U.S. strain would “most likely work in Asia as well because the virus strains in Asia and the United States are very similar.” In 2013, Meng led a team of researchers to identify the origin and possible evolution of the virus when it had only been known to exist in the United States for just a few months. They determined that the virus, which belongs to the coronavirus family, likely originated from China.
The virus infects the cell lining of the pig’s small intestine and leads to acute vomiting, anorexia, and diarrhea with high mortality rates in pigs less than seven to 10 days old. Although it has affected the pork supply and pork prices, researchers have found no evidence that the virus can spread to humans or pose a food safety threat. “In other words, the pork is safe,” Meng said.
Added Rogers, “Although it is new to North America, scientists have known about it since the 1970s when it was first identified in Europe. It has since spread to Asia and has been a significant disease of swine there for quite a long time. In 2013, the virus emerged for the first time in the United States and it has killed at least 8 million piglets in America since then. This past year, it started to slow down, but it is still a major disease.”
Rogers said pork producers have learned more about the virus since its identification in the United States and are now better at spotting symptoms and isolating infected piglets from the rest of the herd. They have also improved biosecurity measures to help prevent the virus from spreading from farm to farm. “However, an effective vaccine will be much better at keeping the virus under control,” Rogers said.
The U.S. Department of Agriculture has granted conditional licenses to two vaccines, but the efficacy of the two conditionally-licensed vaccines in the United States remains to be seen. Meng said there are also attenuated live vaccines available to pork producers mostly in Asia, but these have not successfully controlled the disease there or in Europe.
From research to marketing, vaccine development typically takes five to 10 years before commercialization. The two-year grant not only allows Rogers to take the first steps in developing a new vaccine but also encourages his development as an independent biomedical scientist.
“This is a prestigious grant,” Meng explained. “Adam is the principal investigator on this grant, and it has given him an opportunity to learn how to write a successful grant, manage it, and complete the training that will help him become an independent academic researcher.”
Rogers is the fourth postdoctoral associate in Meng’s laboratory to receive a federal grant to study important swine virus diseases in recent years. The others are Christopher Overend, Shannon Matzinger, and Scott Kenny.
Meng’s lab studies the molecular mechanisms of viral replication and pathogenesis and develops vaccines against emerging, reemerging, and zoonotic viral diseases. In 2006, the lab invented the first USDA fully licensed vaccine against porcine circovirus-associated disease in pigs, which is now commercially available worldwide.