Atypical 'HoBi'-like pestiviruses--recent findings and implications thereof

In 2004, an atypical pestivirus named D32/00_'HoBi', isolated from foetal calf serum (FCS) originating from Brazil, was described (Schirrmeier et al., 2004). A few years later, a closely related virus (Th/04_KhonKaen) was detected in serum from a calf in Thailand, indicating that this group of atypical pestiviruses already is spread in cattle populations in various regions of the world. At the Friedrich-Loeffler-Institute, Insel Riems, Germany, FCS batches are regularly tested for pestivirus contamination, in general with positive PCR results, and in some cases the contaminants have been typed as 'HoBi'-like. At the National Veterinary Institute (SVA) in Uppsala, Sweden, a recent event with contaminated FCS ruined much of the ongoing cell culture work. From the FCS and the contaminated cells we were able to amplify and sequence nucleic acid from three different pestivirus strains, including BVDV-1, -2 and 'HoBi'-like; this in a commercial FCS that had been tested free from pestivirus by the manufacturer. In this short communication we review the current status of atypical 'HoBi'-like pestiviruses, describe recent findings and discuss the implications thereof.