Emergence of canine adenovirus infection in mink from five provinces in Northern China

Canine adenovirus 1 (CAV-1) is the causative agent of canine infectious hepatitis and fox encephalitis. However, epidemiological information regarding CAV-1 infection in mink remains limited. From September 2022 to February 2023, a total of 540 rectal swab samples from 18 mink farms from five provinces in China were collected, and viral nucleic acids were identified, sequenced, and analyzed. The overall positive rate across mink farms was 34.00%, with that of Shandong Province being the highest (67.33%). In Shandong Province, the positive rate of mink CAV-1 in Rizhao city was 100%. According to the fiber phylogenetic tree, the fiber sequences in the cities of Qinhuangdao (042803), Rizhao (042801), and Weihai (050101) were located in the same distinct branch and were different from strains isolated from other animals. These obtained fiber sequences were under purifying selection compared with the CAV-1 fiber (AC_000003.1). Compared with the fiber sequence AP_000069.1, the mutation of the 042402-TS amino acid changed the B-cell epitope and the 3D structure. However, the binding affinity between the obtained fiber sequence and the coxsackievirus and adenovirus receptor (CAR) was not different. These results indicate that strain 042402 exhibits notable genetic divergence in the fiber fragment compared with the strains from other host species, and the prevalence of CAV-1 has been confirmed in mink. Therefore, it is important to further clarify the evolution and molecular epidemiology of CAV-1 in mink in the future.