AMES - Just four months after April 2013's announcement that porcine epidemic diarrhea virus was found in U.S. swine herds, an Ames-based company had a vaccine developed, tested and available for sale.
PEDV has been a pig-killing problem in China, Vietnam and Thailand since 2007. It is virtually 100 percent lethal in young pigs.
Since April 2013, the U.S. swine industry has lost upward to 2 percent of its newborn pig crop.
-Messenger photo by Larry Kershner
Dillion Harris, a production assistant for Harrisvaccines, works over the filtration system that filters the raw vaccine from solutions in the Ames company’s lab.
A few years ago, having a vaccine ready for distribution against a new virus developed in such a short time was unimaginable, since traditional methods can take up to 12 months.
Harrisvaccines has revolutionized the vaccine-production industry using new technology that allows it to respond far more quickly with vaccines for epidemics than the standard method.
The difference? Having the virus is not needed to develop a vaccine.
Called RNA particle platform, this technology uses the genetic sequence of a virus, submitted electronically, to create a vaccine.
No live virus is needed for the process, and therefore no viruses are brought into the laboratory - a major biosecurity benefit.
By copying that part of the genome, a vaccine can be produced in a fraction of the time as in the past.
Dr. Hank Harris, founder and president of Harrisvaccines, said PED virus was a good example of how this vaccine-producing technique has helped the swine industry, since PEDV grows slowly in lab environments.
In addition, he said, because live cultures are being grown in traditional vaccine production, additional safety steps must be in place to prevent a breakout from the lab.
The RNA particle platform technique creates a non-viable culture, which saves time and expense, Harris said.
"We started working on (PEDV) immediately after it was announced," Harris said. "We found the spike gene sequence online, published by the Chinese."
The spike gene is one of the main structural proteins that makes PED capable of inducing neutralizing antibodies.
Harris said they determined the U.S. virus was 99 percent genetically connected with the Asian version.
With testing assistance at Plum Island Animal Disease Center, in Long Island, N.Y., and Kansas State University, Harris said, innoculating weaned pigs showed their immune systems were responding satisfactorily.
Since August, the company has sold up to a million doses, mostly in North Carolina, Iowa and Oklahoma, the three states that have recorded the most outbreaks.
The doses were primarily sold to integrators through veterinary prescription, Harris said.
As it moved in Ontario, Canada, the Canadian Food Inspection Agency has been awarded emergency import permits to purchase the vaccine from the Ames company.
The RNS particle platform technique can develop farm or region-specific vaccines in just four weeks, while conventional production methods can take up to 12 months.
This allows for rapid response to farm-specific disease outbreaks.
As diseases are constantly evolving, this is crucial to containment and eradication efforts.
Harris said the first generation of the PEDV vaccine used a portion of the spike gene and the second generation used the entire sequence, both getting good responses.
Harrisvaccines focuses primarily on swine diseases. Prior to PEDV, its most sought-for vaccine was for porcine reproductive and respiratory diseases and H1N1 influenza.
New PED strain
With production ongoing, the company has turned its attention on a second strain of the PED virus has been detected.
Iowa State University researchers announced on Feb. 2 that another strain was found in five of 15 suspected PEDV cases from Jan. 24 through Jan. 29.
"Based on the data currently available," the ISU report said, "it appears unlikely that this strain is a mutant evolved from PEDV previously identified in U.S. swine.
"Determination of the entire genome sequences of these new PEDVs are in progress and will help determine the origin of the viruses."
Harris said research in Virginia Polytechnic Institute in Blackburg, Va., determined the first PEDV in the U.S. came from China.
"But how it got here," Harris said, "is a mystery."
Dr. Mark Mogler, head of research at Harrisvaccines, said it is unclear if the current vaccine will work against the new strain.
"But it's relatively simple to develop a new vaccine if needed," he said. "That's the feature. We can respond quickly to epidemic diseases."
Harrisvaccines announced on Jan. 30 it was granted an autogenous licensure of its rotavirus C vaccine by the United States Department of Agriculture.
The license is for the SirraVax RNA Particle Technology, approved by USDA's Center for Veterinary Biologics, for disease caused by rotavirus subtype C.
Rotavirus C is a cause of diarrhea and mortality in young piglets. Preparing effective vaccines using traditional methods is difficult, due to the poor growth characteristics of rotavirus in laboratory cell culture.
This is the first time SirraVax technology has been granted an autogenous license, the company said in a news release.
Harrisvaccines received a USDA license using SirraVax technology for swine influenza vaccine, RNA in September 2012, which is licensed as an aid in the prevention of disease caused by H3N2.
Harrisvaccines has submitted a conditional license application for its PEDV vaccine which is anticipated to gain approval in 2014.