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The first animal study of a pig virus’s potential to jump to another species shows that the virus, once introduced to a select group of birds, is easily transmitted to healthy chickens and turkeys.
The researchers who led this work were part of a team that previously found in a lab setting that the virus could infect cells from multiple species, including chickens and humans.
In this study, birds that were given the virus developed diarrhea by two days after infection. Healthy birds housed with infected chickens and turkeys also developed diarrhea two days after exposure.
That rapid spread of disease surprised the Ohio State University scientists.
“We weren’t even sure the virus would transmit from bird to bird. That’s a significant finding,” said senior author Scott Kenney, assistant professor of veterinary preventive medicine based in Ohio State’s Food Animal Health Research Program at the Ohio Agricultural Research and Development Center (OARDC) in Wooster.
“It looks like it’s pretty readily able to spread between birds. It’s a little concerning because if the virus gets into one or two animals in a large layer or broiler house, it would probably permeate through the entire house pretty quickly,” Kenney said.
Susceptibility to a pig virus can’t ethically be tested in humans – but the previous work in cells showed the virus attaches itself to the same type of receptor in many different host species.
“If the human cell culture model is as predictive as it was with the chickens, then humans are definitely susceptible to having virus-related disease,” he said.
The study is published in the online journal Emerging Infectious Diseases.
This virus, porcine deltacoronavirus, was first detected in pigs in Asia in 2009 and caused a swine diarrhea outbreak in the United States – involving Ohio pigs – in 2014. It is part of the family of pathogens that cause respiratory and gastrointestinal diseases in the species they infect.
There are four types of coronaviruses. Two illnesses known for life-threatening regional outbreaks, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), were caused by betacoronaviruses. The current respiratory disease outbreak associated with a live animal market in China is also attributed to a betacoronavirus. Deltacoronaviruses historically have been linked to birds, and scientists suspect that this porcine virus originated in an avian species.
In this study, researchers worked with 14-day-old chickens and turkeys. In each group, they directly gave 10 birds the virus obtained from an infected pig. Two days later, the researchers allowed uninfected “sentinel” chickens and turkeys to live among the infected birds.