Serological and molecular evidence for natural infection of Bactrian camels with multiple subgenotypes of bovine viral diarrhea virus in Western China

Bovine viral diarrhea virus (BVDV) infects both domestic and wild animals, causing substantial economic losses. In order to investigate possible infection in Bactrian camels in Western China, a total of 56 blood samples were collected from clinically healthy Bactrian camels and tested for BVDV antigens and antibodies using antigen capture enzyme-linked immunosorbent assay (ELISA) and virus neutralization test. The antigen-positive samples (n = 17) were further tested for viral nucleic acids by species-specific real-time RT-PCR assays, which showed presence of BVDV-1, but not BVDV-2 nor atypical bovine pestivirus, in the camel samples. Twelve non-cytopathogenic viruses were isolated and genetically typed by sequencing of the 5′untranslated region (5′UTR) and Npro coding sequences. Phylogenetic analysis divided the isolates into six known subgenotypes: BVDV-1a, BVDV-1b, BVDV-1c, BVDV-1m, BVDV-1o, BVDV-1p and a putative subgenotype, BVDV-1q. This study provides, for the first time, serological and molecular evidence for natural infection of Bactrian camels in Western China with highly divergent BVDV-1 strains. Further investigations are needed to elucidate the possible roles of Bactrian camels in the epidemiology of BVD in Western China.