Analysis of the Properties of Bovine Viral Diarrhea Virus Isolated from the Australian Imported Cattle Herd and the Status of Possession of Neutralizing Antibodies in the Group

Abstract

We analyzed the properties of bovine viral diarrhea virus (BVDV) isolated from an Australian dairy breeding herd in which cattle persistently infected with BVDV (PI cattle) were detected during the import quarantine period, and the BVDV neutralizing antibody titer in the imported herd was measured. The isolate was grouped in subtype 1c. The isolate showed high cross-reactivity to the immune sera of the 1a vaccine strain in Japan. This suggests that vaccines which are marketed in Japan are effective in the prevention of the spread of isolates. Cattle imported from Australia were vaccinated with the BVDV-1c inactivated vaccine prior to export to Japan. When the neutralizing antibody titers in the initial serum of the research herd were examined, they possessed a high antibody titer (GM value, 1:510) against the 1c. Antibodies that are thought to cross-react against 1a, 1b sub-genotypes and type 2 strains were also detected, which are commonly isolated in Japan. Furthermore, the rise of the neutralizing antibody attributable to the existence of the PI cattle was recognized in 30 of the 166 cattle.