Study finds Porcine deltacoronavirus is easily transmitted among chickens and turkeys

Experimental Porcine deltacoronavirus (PDCoV) infection and subsequent transmission among poultry is reported in Emerging Infectious Diseases.

The Ohio State University researchers who led this work were part of a team that previously found in a laboratory setting that the virus could infect cells from multiple species, including chickens and humans.

In the latest study, birds that were infected with PDCoV developed diarrhoea by two days after inoculation. Healthy birds housed with infected chickens and turkeys also developed diarrhoea 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.

Previous work in cells showed the virus attaches itself to the same type of receptor in many different host species, including humans.

“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.

For the experimental infection, 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.

Most infected birds developed diarrhoea at various time points, and the sentinels had mild to moderate diarrhoea after joining the infected flock. Based on the length and severity of symptoms, the study showed that turkeys are more susceptible to the virus than chickens.

Other signs of disease in the birds included distended intestinal tracts containing gas and yellow liquid, high levels of the virus RNA in swabs of their tracheas and digestive tracts, and increased antibody levels in the directly infected birds and some sentinels, said Patricia Boley, first author of the study and a research associate in Kenney’s lab.

“Both chickens and turkeys were still shedding the virus at 14 days, when the study ended. We don’t know how long either species would continue shedding the virus,” Boley said.

Despite the presence of virus RNA in the trachea, the birds showed no signs of respiratory symptoms, which would make this virus more dangerous than enteric symptoms. The virus also did not kill the birds, but it can lead to death in piglets.

“We want to figure out why the virus is enteric versus respiratory, and how the hosts respond differently,” Kenney said. “With piglets we see mortality. We don’t have chickens dying, but we have piglets dying from the virus, so what makes the chickens different in their response to the virus? Maybe we can learn something from chickens and apply it to the pigs so they get less sick from the virus.”

The work was supported by the National Institute of Food and Agriculture’s funding to the Food Animal Health Research Program.

Article: Boley, P. A., Alhamo, M. A., Lossie, G., Yadav, K. K., Vasquez-Lee, M., Saif, L. J., Kenney, S. P. (2020). Porcine deltacoronavirus infection and transmission in poultry, United States. Emerging Infectious Diseases, vol. 26, no. 2 [Early Release] doi: 10.3201/eid2602.190346

[SOURCE: Ohio State University]

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