2.2 Sample collection
In total, 571 serum samples were collected from apparently healthy
pigeons from 39 racing pigeon clubs between November 2016 and August
2019 in 11 provinces or municipalities of China including Beijing,
Hebei, Liaoning, Shanxi, Gansu, Qinghai, Shandong, Shaanxi, the Xinjiang
Uygur Autonomous Region, Ningxia Hui Autonomous Region and Inner
Mongolia Autonomous Region. Moreover, fifty-one fatally diseased racing
pigeons from 7 racing pigeon club of the 5 provinces or municipalities
were submitted to our laboratory in College of Veterinary Medicine,
Northwest A&F University to determine the pathogen of the disease. The
0.2 g sections of internal organs (the heart, liver, spleen, lung, and
intestine) were obtained during the postmortem examination of all
mentioned above dead pigeons. All samples were stored at −80°C before
DNA extraction.