Researchers in South Dakota State University’s Animal Disease Research and Diagnostic Laboratory are racing to develop a vaccine for a new strain of a highly contagious disease that is currently wreaking havoc on the U.S. poultry industry.
Avian metapneumovirus, or aMPV, is an upper respiratory tract viral infection that affects all types of poultry but is most harmful to turkeys. The virus is divided into four different subgroups: A, B, C or D. While each subgroup can be found in different parts of the world, the U.S. has previously only experienced outbreaks of subgroup C.
That was until last January.
SDSU assistant professor Sunil Mor and his research team identified the U.S.’s first known instance of aMPV subgroup B after testing a sample from an outbreak in a North Carolina turkey flock. The news of subgroup B’s arrival was surprising to virologists and veterinarians around the U.S. and sent shockwaves through the U.S.’s $67 billion poultry industry. Four months after Mor identified the virus, it had spread to all the major poultry-producing regions in the U.S.
Minnesota is the country’s largest producer of turkeys, and reports from the state’s independent producers during a recent aMPV working group session paint a grim picture. Egg shortages. Thousands of dead birds. Entire operations on the brink of bankruptcy.
The virus is challenging in that it “moves silently,” according to Mor. Once a producer notices symptoms, like a cough, nasal discharge or swelling, the entire flock is already most likely infected. The aMPV virus doesn’t usually outright kill the birds, Mor said. But it weakens their immune system so much that a secondary infection, like E. coli, will. With limited antibiotics available for treatment, the challenges turkey producers face are being compounded.
“Producers are facing the issue from different sides,” Mor said. “This is why the virus is so threatening. The economic impact is huge.”
This all comes at a time when the turkey industry is still reeling from the highly pathogenic avian influenza (HPAI) and other ongoing diseases.
Official numbers of aMPV cases are difficult to count because the U.S. Department of Agriculture does not officially track aMPV infections. However, the National Turkey Federation estimated in September that the virus is present in 60-80% of U.S. flocks.
It’s not just turkeys being affected; chickens are dying, albeit at a lower rate. Turkey breeders are also seeing significant reductions in eggs being produced, which is leading to a national shortage of poults.
The SDSU team, headed by Mor and Tamer Sharafeldin, an SDSU assistant professor and veterinary pathologist, is leading a nationwide effort to develop safe and effective vaccines for aMPV subgroup B. Vaccine development began immediately after subgroup B was first identified back in January. The team successfully isolated the virus in just four weeks and since been able to “weaken” it — a key part of vaccine development. Now, the researchers are in the process of developing the baseline criteria for testing the vaccine’s efficacy.
“Our main concern right now is developing the vaccine,” Sharafeldin said. “It’s our top priority.”
But the vaccine is only part of the solution. The SDSU team is also working to develop very specific diagnostic testing that will help producers identify the virus quicker.
“There’s a very small window to detect the virus,” Mor said. “This testing is more specific to subgroup A and subgroup B.”
Improved testing will help producers manage this multifaceted challenge better while the vaccine is in development, which in these instances, takes around two to three years to get on the market. However, the circumstances may allow for the vaccine to be expediated, and Mor is hopeful the development timeline can be shortened.
“We are working hard to provide the vaccines to producers,” Mor said. “Our target is next year, hopefully in the fall, to complete all vaccine trials.”
The SDSU team is working to not only develop a safe and effective vaccine, but also to improve testing. This will help poultry producers minimize loses while the vaccine is in development.
aMPV poses little to no risk to humans. While other metapneumoviruses may affect humans, aMPV does not. Turkeys that have been infected with aMPV and pass USDA inspection at slaughter are also safe to eat.
The SDSU team members, the first to discover aMPV subgroup B in the U.S. and the first to isolate the virus, have cemented themselves as nationally recognized leaders in aMPV research and are continuing to work closely with poultry producers and industry stakeholders to solve this complex challenge.
“I am impressed with Dr. Mor’s close connections to poultry production stakeholders and his responsiveness to help improve the health of their flocks,” said Angela Pillatzki, director of Animal Disease Research and Diagnostic Laboratory. “His research contributions will positively impact poultry production for years to come.”
Source: South Dakota State University
