Detection and Identification of the Atypical Bovine Pestiviruses in Commercial Foetal Bovine Serum Batches

The recently emerging atypical bovine pestiviruses have been detected in commercial foetal bovine serum (FBS) of mainly South American origin so far. It is unclear how widely the viruses are presented in commercial FBS of different geographic origins. To further investigate the possible pestivirus contamination of commercially available FBS batches, 33 batches of FBS were obtained from ten suppliers and analysed in this study for the presence of both the recognised and the atypical bovine pestiviruses. All 33 batches of FBS were positive by real-time RT-PCR assays for at least one species of bovine pestiviruses. According to the certificate of analysis that the suppliers claimed for each batch of FBS, BVDV-1 was detected in all 11 countries and BVDV-2 was detected exclusively in the America Continent. The atypical pestiviruses were detected in 13 batches claimed to originate from five countries. Analysis of partial 5′UTR sequences showed a high similarity among these atypical bovine pestiviruses. This study has demonstrated, for the first time that commercial FBS batches of different geographic origins are contaminated not only with the recognised species BVDV-1 and BVDV-2, but also with the emerging atypical bovine pestiviruses

Coronavirus Gene 7 Counteracts Host Defenses and Modulates Virus Virulence

Transmissible gastroenteritis virus (TGEV) genome contains three accessory genes: 3a, 3b and 7. Gene 7 is only present in members of coronavirus genus a1, and encodes a hydrophobic protein of 78 aa. To study gene 7 function, a recombinant TGEV virus lacking gene 7 was engineered (rTGEV-Δ7). Both the mutant and the parental (rTGEV-wt) viruses showed the same growth and viral RNA accumulation kinetics in tissue cultures. Nevertheless, cells infected with rTGEV-Δ7 virus showed an increased cytopathic effect caused by an enhanced apoptosis mediated by caspase activation. Macromolecular synthesis analysis showed that rTGEV-Δ7 virus infection led to host translational shut-off and increased cellular RNA degradation compared with rTGEV-wt infection. An increase of eukaryotic translation initiation factor 2 (eIF2α) phosphorylation and an enhanced nuclease, most likely RNase L, activity were observed in rTGEV-Δ7 virus infected cells. These results suggested that the removal of gene 7 promoted an intensified dsRNA-activated host antiviral response. In protein 7 a conserved sequence motif that potentially mediates binding to protein phosphatase 1 catalytic subunit (PP1c), a key regulator of the cell antiviral defenses, was identified. We postulated that TGEV protein 7 may counteract host antiviral response by its association with PP1c. In fact, pull-down assays demonstrated the interaction between TGEV protein 7, but not a protein 7 mutant lacking PP1c binding motif, with PP1. Moreover, the interaction between protein 7 and PP1 was required, during the infection, for eIF2α dephosphorylation and inhibition of cell RNA degradation. Inoculation of newborn piglets with rTGEV-Δ7 and rTGEV-wt viruses showed that rTGEV-Δ7 virus presented accelerated growth kinetics and pathology compared with the parental virus. Overall, the results indicated that gene 7 counteracted host cell defenses, and modified TGEV persistence increasing TGEV survival. Therefore, the acquisition of gene 7 by the TGEV genome most likely has provided a selective advantage to the virus

Bovine Viral Diarrhea Virus Proteins - Relatedness of P175 with P80 and P125 and Evidence of Glycoprotein Processing

Three monoclonal antibodies, which recognized two nonoverlapping antigenic domains and were reactive to the bovine viral diarrhea virus (BVDV) p80 protein, were found to cross react with the p125 protein of both cytopathic and noncytopathic BVDVs and a molecular weight 175000 BVDV protein (p175). Results from limited proteolysis and chemical cleavage experiments confirmed the relatedness of these three proteins. In pulse-chase experiments it was apparent that p175 was a transient protein, as it was diminished during the chase, with a half-life of about 30 min. However, both p125 and p80 were also observed in short-pulsed lysates. Furthermore, during the chase, radiolabel was not found to accumulate into p125 or p80. Rather, these two proteins were stable with half-lives greater than 2 h. A fourth nonglycosylated protein, p37, increased during the chase. Processing of several glycoproteins was evident in these experiments. A glycoprotein of molecular weight 75000 (gp75) diminished during the chase period, while glycoproteins gp62, gp48, and gp25 appeared or increased during the chase period. In contrast, the glycoprotein gp53 was a major protein in pulse-labeled cell lysates and remained constant throughout the chase period. In further experiments two stable forms of p80 differing in intramolecular disulphide bonding were observed