Detection and genetic characterization of chicken astrovirus and avian nephritis virus from hatchery to farm

Astroviruses are an emerging hazard in hatchery management, and they are responsible forgreat economic losses in poultry farms worldwide. Chicken astrovirus (CAstV) and aviannephritis virus (ANV) are involved in decreased hatching rate, mainly due to embryo deaths,and pale and runted chicks too weak to hatch. Hatchery diseases occur through direct egginfection or vertical transmission. However, the specific role of astroviruses in these diseasesis still largely unknown. To elucidate this a high-quality Piedmont hatchery (Italy) wasselected based on farm clinical signs and the astrovirus serological positivity in the breederfarm. The viral dynamics were followed from the hatchery to the farm. The presence of bothCAstV and ANV was monitored by evaluating the viral load in environmental and birdsamples. Interestingly, both viruses were detected in chick yolk sacs at 18 days ofincubation, and in the gut contents of 1-day chicks, whereas in the hatchery environmentalsamples, the eggs’ external surfaces and the embryos’ intestinal contents were negative. TheCAstV copy number was higher in bird tissues from the hatchery, while a greater ANV loadwas detected in bird tissues from the farm. Moreover, our data suggest vertical transmissionof both viruses. Frequent co-infection was also observed in samples from both the hatcheryand the farm. Lastly, the first Italian full-length genome and molecular characterization ofANV was obtained.