Identification and Genetic Evolution Analysis of One Strain of H3N2 Canine Influenza Virus Isolated from Nanjing, China

Nasopharyngeal swabs were collected from 6 dogs with severe respiratory syndrome at the Animal Clinics of Nanjing Agricultural University in 2014. One viral strain was isolated from SPF embryonated chicken eggs. Sequencing analysis of hemagglutinin (HA) and neuraminidase (NA) genes showed 93 to 99% similarity between each other. The CIV isolates shared high similarity (above 98%) to the H3N2 viruses from dogs in China. On the comparison of gene sequence four unique mutations were found in the amino acid of HA (A144T, R158K, D291N, L383F) and NA (T19A, V33L, V82A, S336N). The HA and NA genetic evolution analysis revealed that one isolate was most similar to the newly isolated H3N2 viruses from dogs in China and had the same evolutionary branching. The result provided a foundation for further studies on biological characteristics of CIV.