UNIVERSITY PARK, Pa., April 23 (UPI) -- Live vaccines that protect domestic poultry against Newcastle disease may be creating unpredictable wild virus strains, scientists in Pennsylvania said.
Newcastle disease is a bird-contagious influenza-like disease that costs the poultry industry millions of dollars annually.
While the live vaccines against Newcastle work in the short term, they may be making it more difficult to fight in the long term, said Mary Poss, professor of biomedical sciences at Pennsylvania State University.
Vaccinated birds can shed the vaccine virus to infect wild birds, Poss said, noting her team found new viruses were created when a vaccine strain was combined with at least three wild strains.
"This raises concerns that modified live virus vaccines, though effective, may combine with circulating viruses to create unpredictable new strains," Poss and her team wrote in a recent issue of PLoS Pathogens.
Vaccine developers who now use modified live viruses should consider using killed or inactivated viruses, she said.
