Network of Interactions between the Mut Domains of the E2 Protein of Atypical Porcine Pestivirus and Host Proteins.

Atypical porcine pestivirus (APPV) can cause congenital tremor type A-II in neonatal piglets, posing a significant threat to swine herd health globally. Our previous study demonstrated that the Mut domains, comprising 112 amino acids at the N-terminus, are the primary functional regions of the E2 protein of APPV. This study identified 14 host cellular proteins that exhibit potential interactions with the Mut domains of the E2 protein using yeast two-hybrid screening. Using bioinformatics analysis, we discovered that the Mut domains of the E2 protein might exert regulatory effects on apoptosis by modulating energy metabolism within the mitochondria. We also conducted co-immunoprecipitation, glutathione S-transferase pull-down, and immunofluorescence assays to confirm the interaction between the Mut domains of the E2 protein and cathepsin H and signal sequence receptor subunit 4 (SSR4). Ultimately, SSR4 enhanced APPV replication in vitro. In summary, our study successfully elucidated the interactions between the Mut domains of the E2 protein and host cell protein, predicted the potential pathways implicated in these interactions, and demonstrated SSR4 involvement in APPV infection. These significant findings contribute valuable knowledge toward a deeper understanding of APPV pathogenesis and the role of the Mut domains of the E2 protein in this intricate process.

Proposed Update to the Taxonomy of Pestiviruses: Eight Additional Species within the Genus Pestivirus, Family Flaviviridae.

Pestiviruses are plus-stranded RNA viruses belonging to the family Flaviviridae. They comprise several important pathogens like classical swine fever virus and bovine viral diarrhea virus that induce economically important animal diseases. In 2017, the last update of pestivirus taxonomy resulted in demarcation of 11 species designated Pestivirus A through Pestivirus K. Since then, multiple new pestiviruses have been reported including pathogens associated with disease in pigs or small ruminants. In addition, pestivirus sequences have been found during metagenomics analysis of different non-ungulate hosts (bats, rodents, whale, and pangolin), but the consequences of this pestivirus diversity for animal health still need to be established. To provide a systematic classification of the newly discovered viruses, we analyzed the genetic relationship based on complete coding sequences (cds) and deduced polyprotein sequences and calculated pairwise distances that allow species demarcation. In addition, phylogenetic analysis was performed based on a highly conserved region within the non-structural protein NS5B. Taking into account the genetic relationships observed together with available information about antigenic properties, host origin, and characteristics of disease, we propose to expand the number of pestivirus species to 19 by adding eight additional species designated Pestivirus L through Pestivirus S.

The Erns Carboxyterminus: Much More Than a Membrane Anchor.

Pestiviruses express the unique essential envelope protein Erns, which exhibits RNase activity, is attached to membranes by a long amphipathic helix, and is partially secreted from infected cells. The RNase activity of Erns is directly connected with pestivirus virulence. Formation of homodimers and secretion of the protein are hypothesized to be important for its role as a virulence factor, which impairs the host's innate immune response to pestivirus infection. The unusual membrane anchor of Erns raises questions with regard to proteolytic processing of the viral polyprotein at the Erns carboxy-terminus. Moreover, the membrane anchor is crucial for establishing the critical equilibrium between retention and secretion and ensures intracellular accumulation of the protein at the site of virus budding so that it is available to serve both as structural component of the virion and factor controlling host immune reactions. In the present manuscript, we summarize published as well as new data on the molecular features of Erns including aspects of its interplay with the other two envelope proteins with a special focus on the biochemistry of the Erns membrane anchor.

Vaccination with virus-like particles of atypical porcine pestivirus inhibits virus replication in tissues of BALB/c mice.

Congenital tremor (CT) type A-II in piglets is a worldwide disease caused by an emerging atypical porcine pestivirus (APPV). Preparation and evaluation of vaccines in laboratory animals is an important preliminary step toward prevention and control of the disease. Here, virus-like particles (VLPs) of APPV were prepared and VLPs vaccine was evaluated in BALB/c mice. Purified Erns and E2 proteins expressed in E. coli were allowed to self-assemble into VLPs, which had the appearance of hollow spherical particles with a diameter of about 100 nm by transmission electron microscopy (TEM). The VLPs induced strong antibody responses and reduced the viral load in tissues of BALB/c mice. The data from animal challenge experiments, RT-PCR, and immunohistochemical analysis demonstrated that BALB/c mice are an appropriate laboratory model for APPV. These results suggest the feasibility of using VLPs as a vaccine for the prevention and control of APPV and provide useful information for further study of APPV in laboratory animals.

Autonomously Replicating RNAs of Bungowannah Pestivirus: ERNS Is Not Essential for the Generation of Infectious Particles.

Autonomously replicating subgenomic Bungowannah virus (BuPV) RNAs (BuPV replicons) with deletions of the genome regions encoding the structural proteins C, ERNS, E1, and E2 were constructed on the basis of an infectious cDNA clone of BuPV. Nanoluciferase (Nluc) insertion was used to compare the replication efficiencies of all constructs after electroporation of in vitro-transcribed RNA from the different clones. Deletion of C, E1, E2, or the complete structural protein genome region (C-ERNS-E1-E2) prevented the production of infectious progeny virus, whereas deletion of ERNS still allowed the generation of infectious particles. However, those ΔERNS viral particles were defective in virus assembly and/or egress and could not be further propagated for more than three additional passages in porcine SK-6 cells. These "defective-in-third-cycle" BuPV ΔERNS mutants were subsequently used to express the classical swine fever virus envelope protein E2, the N-terminal domain of the Schmallenberg virus Gc protein, and the receptor binding domain of the Middle East respiratory syndrome coronavirus spike protein. The constructs could be efficiently complemented and further passaged in SK-6 cells constitutively expressing the BuPV ERNS protein. Importantly, BuPVs are able to infect a wide variety of target cell lines, allowing expression in a very wide host spectrum. Therefore, we suggest that packaged BuPV ΔERNS replicon particles have potential as broad-spectrum viral vectors.IMPORTANCE The proteins NPRO and ERNS are unique for the genus Pestivirus, but only NPRO has been demonstrated to be nonessential for in vitro growth. While this was also speculated for ERNS, it has always been previously shown that pestivirus replicons with deletions of the structural proteins ERNS, E1, or E2 did not produce any infectious progeny virus in susceptible host cells. Here, we demonstrated for the first time that BuPV ERNS is dispensable for the generation of infectious virus particles but still important for efficient passaging. The ERNS-defective BuPV particles showed clearly limited growth in cell culture but were capable of several rounds of infection, expression of foreign genes, and highly efficient trans-complementation to rescue virus replicon particles (VRPs). The noncytopathic characteristics and the absence of preexisting immunity to BuPV in human populations and livestock also provide a significant benefit for a possible use, e.g., as a vector vaccine platform.

Characterization of the Humoral Immune Response Induced after Infection with Atypical Porcine Pestivirus (APPV).

Atypical porcine pestivirus (APPV) is a widely distributed pathogen causing congenital tremor (CT) in piglets. So far, no data are available regarding the humoral immune response against APPV. In this study, piglets and their sows from an affected herd were tested longitudinally for viral genome and antibodies. APPV genome was detected in the majority of the piglets (14/15) from CT affected litters. Transient infection of gilts was observed. Kinetics of Erns- and E2-specific antibodies and their neutralizing capacity were determined by recently (Erns) and newly (E2) developed antibody ELISAs and virus neutralization assays. Putative maternally derived antibodies (MDA) were detected in most piglets, but displayed only low to moderate neutralizing capacity (ND50 ≤ 112). Horizontal APPV transmission occurred when uninfected and infected piglets were mingled on the flat deck. Horizontally infected piglets were clinically inapparent and showed only transient viremia with subsequently consistently high E2 antibody levels. For piglets from CT affected litters, significantly lower neutralizing antibody titers were observed. Results indicate that E2 represents the main target of neutralizing antibodies. Characterization of the humoral immune response against APPV will help to provide valuable serological diagnosis, to understand the epidemiology of this novel pathogen, and to implement tailored prevention strategies.

Molecular characterization of two novel atypical porcine pestivirus (APPV) strains from piglets with congenital tremor in China.

As one of emerging porcine viruses, atypical porcine pestivirus (APPV) was found in three continents since it emerged in 2015. It is now thought as the causative agent for congenital tremor type A-II in piglets. At the end of 2017, two APPV strains were identified from piglets with congenital tremor in Guangxi and Yunnan, China. The genome of APPV GX04/2017 strain was so far determined to be 11,534 nucleotides (nt) in length and contains a single open reading frame (ORF) encoding a polyprotein comprising 3,635 amino acids. Comparative analysis of ORF, Npro , E2, and NS3 gene sequences revealed that the APPV GX04/2017 strain shares nucleotide sequence identities of 82.8%-92.8% with other APPV strains, while YN01/2017 strain is 79.4%-97.4% homology to the others. Phylogenetic analysis showed that the APPV GX04/2017 and YN01/2017 are two novel APPV strains with the highest homology to each other, and relative high similarity to the APPV 000515 and JX-JM01 strains in genome sequence. The current findings provide updated information about APPV epidemiology and divergence in China, which would certainly help to establish reliable diagnosis and surveillance programs for APPV.

Identification of structural glycoprotein E2 domain critical to mediate replication of Classical Swine Fever Virus in SK6 cells.

Envelope glycoprotein E2 of Classical Swine Fever Virus (CSFV) is involved in several critical virus functions. To analyze the role of E2 in virus replication, a series of recombinant CSFVs harboring chimeric forms of E2 CSFV and Bovine viral diarrhea virus (BVDV) were created and tested for their ability to infect swine or bovine cell lines. Substitution of native CSFV E2 by BVDV E2 abrogates virus replication in both cell lines. Substitution of individual domains in CSFV Brescia E2 by the homologous from BVDV produces chimeras that efficiently replicate in SK6 cells with the exception of a chimera harboring BVDV E2 residues 93-168. Further mapping revealed a critical area in E2 required for CSFV replication in SK6 cells between protein residues 136-156. This is the first report categorically defining a discrete portion of E2 as essential to pestivirus infection in susceptible cells.

Experimental infection of mice with noncytopathic bovine viral diarrhea virus 2 increases the number of megakaryocytes in bone marrow.

BACKGROUND: Bovine viral diarrhea virus (BVDV) causes significant economic losses worldwide in the cattle industry through decrease in productive performance and immunosuppression of animals in herds. Recent studies conducted by our group showed that mice can be infected with BVDV-1 by the oral route. The purpose of this study was to assess the clinical signs, hematological changes, histopathological lesions in lymphoid tissues, and the distribution of the viral antigen after oral inoculation with a Korean noncytopathic (ncp) BVDV-2 field isolate in mice. METHODS: Mice were orally administered a low or high dose of BVDV-2; blood and tissue samples were collected on days 2, 5, and 9 postinfection (pi). We monitored clinical signs, hematological changes, histopathological lesions, and tissue distribution of a viral antigen by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) and then compared these parameters with those in ncp BVDV-1 infections. RESULTS: None of the infected mice developed any clinical signs of the illness. Significant thrombocytopenia was found in both low- and high-dose-inoculated mice on day 2 pi. Leukopenia was apparent only in low-dose-inoculated mice on day 2 pi, whereas lymphopenia was not observed in any ncp BVDV-2-infected animal. Viral RNA was found in the spleen in of low- and high-dose-inoculated mice by RT-PCR. According to the results of IHC, the viral antigen was consistently detected in lymphocytes of bone marrow and spleen and less frequently in bronchus-associated lymphoid tissue (BALT), mesenteric lymph nodes, and Peyer's patches. Despite the antigen detection in BALT and mesenteric lymph nodes, histopathological lesions were not observed in these tissues. Lympholysis, infiltration by inflammatory cells, and increased numbers of megakaryocytes were seen in Peyer's patches, spleens, and bone marrow, respectively. In contrast to ncp BVDV-1 infection, lympholysis was found in the spleen of ncp BVDV-2-infected mice. These histopathological lesions were more severe in high-dose-inoculated mice than in low-dose-inoculated mice. CONCLUSIONS: Our results provide insight into the pathogenesis of ncp BVDV-2 infection in mice. Collectively, these results highlight significant differences in pathogenesis between ncp BVDV-1 and ncp BVDV-2 infections in a murine model.

Characterization of a Pestivirus H isolate originating from goats.

Natural Pestivirus H infections in cattle have been reported worldwide; however, only a few cases of Pestivirus H have been described in non-bovine ruminants such as goats. A new Pestivirus H HN1507 strain was isolated from an infected goat in 2015 and the genome sequence was determined. The full-length genome sequence was 12,556 nucleotides. Phylogenetic analysis, based on the complete genome and Npro fragments, revealed that the isolate belonged to Pestivirus H and was closely related to strains from Italy. Two unique amino acid substitutions were found in the C-terminal of the E2 protein. To the best of our knowledge, this is first report determining the complete genome of a Pestivirus H strain from goat.

Phylogenetic and genomic characterization of a novel atypical porcine pestivirus in China.

Atypical porcine pestivirus (APPV) has been considered a novel pestivirus and causative agent of congenital tremor type A-II. An APPV CH-GX2016 strain was characterized from newly born piglets with clinical symptoms of congenital tremor in Guangxi, China. The genome of APPV CH-GX 2016 strain was 11,475 bp in length and encoded a polyprotein composed of the 3,635 amino acids. This genome sequence exhibited 88.0% to 90.8% nucleotide sequence homology with other APPV reference sequences in GenBank. Phylogenetic analysis further showed that APPV CH-GX is a novel pestivirus compared with previously described classical pestivirus strains. Therefore, APPV is present in pigs in China.

Uncoupling of Protease trans-Cleavage and Helicase Activities in Pestivirus NS3.

The nonstructural protein NS3 from the Flaviviridae family is a multifunctional protein that contains an N-terminal protease and a C-terminal helicase, playing essential roles in viral polyprotein processing and genome replication. Here we report a full-length crystal structure of the classical swine fever virus (CSFV) NS3 in complex with its NS4A protease cofactor segment (PCS) at a 2.35-Å resolution. The structure reveals a previously unidentified ∼2,200-Å2 intramolecular protease-helicase interface comprising three clusters of interactions, representing a "closed" global conformation related to the NS3-NS4A cis-cleavage event. Although this conformation is incompatible with protease trans-cleavage, it appears to be functionally important and beneficial to the helicase activity, as the mutations designed to perturb this conformation impaired both the helicase activities in vitro and virus production in vivo Our work reveals important features of protease-helicase coordination in pestivirus NS3 and provides a key basis for how different conformational states may explicitly contribute to certain functions of this natural protease-helicase fusion protein.IMPORTANCE Many RNA viruses encode helicases to aid their RNA genome replication and transcription by unwinding structured RNA. Being naturally fused to a protease participating in viral polyprotein processing, the NS3 helicases encoded by the Flaviviridae family viruses are unique. Therefore, how these two enzyme modules coordinate in a single polypeptide is of particular interest. Here we report a previously unidentified conformation of pestivirus NS3 in complex with its NS4A protease cofactor segment (PCS). This conformational state is related to the protease cis-cleavage event and is optimal for the function of helicase. This work provides an important basis to understand how different enzymatic activities of NS3 may be achieved by the coordination between the protease and helicase through different conformational states.

The core protein of a pestivirus protects the incoming virus against IFN-induced effectors.

A multitude of viral factors - either inhibiting the induction of the IFN-system or its effectors - have been described to date. However, little is known about the role of structural components of the incoming virus particle in protecting against IFN-induced antiviral factors during or immediately after entry. In this study, we take advantage of the previously reported property of Classical swine fever virus (family Flaviviridae, genus Pestivirus) to tolerate a deletion of the core protein if a compensatory mutation is present in the NS3-helicase-domain (Vp447∆c). In contrast to the parental virus (Vp447), which causes a hemorrhagic-fever-like disease in pigs, Vp447∆c is avirulent in vivo. In comparison to Vp447, growth of Vp447∆c in primary porcine cells and IFN-treated porcine cell lines was reduced >20-fold. Also, primary porcine endothelial cells and IFN-pretreated porcine cell lines were 8-24 times less susceptible to Vp447∆c. This reduction of susceptibility could be partially reversed by loading Vp447∆c particles with different levels of core protein. In contrast, expression of core protein in the recipient cell did not have any beneficial effect. Therefore, a protective effect of core protein in the incoming virus particle against the products of IFN-stimulated genes could be demonstrated.

Pig BVDV-2 non-structural protein (Npro) links to cellular antiviral response in vitro.

In this study, we constructed for the first time a full-length cDNA clone of pig-original bovine viral diarrhea virus 2 (BVDV-2) strain SH-28, modified the cDNA clone (pASH28) for mutant pASHΔNpro and derived virus strain vASHΔNpro by deleting the genomic region encoding the Npro polypeptide, and examined significance of protein Npro for antiviral responses in vitro. Data showed that Npro-deletion mutant virus vASHΔNpro led to significant overexpression of oligo adenylate synthetase (OAS), myxovirus-resistant protein 1 (Mx1), and ubiquitin-like protein 15 (ISG15). Data also revealed that overexpression of Npro, but not NS2 and NS3 proteins, resulted in significant down-regulation of OAS, Mx1, and ISG15 production (p ≤ 0.05) in bovine cells as well as porcine cells transfected with Npro recombinant eukaryotic expression plasmids. Npro (but not NS2 and NS3) was also found to inhibit poly(IC) from inducing production of type I interferon (IFN-I). These results indicated that protein Npro may play multiple roles in regulating antiviral response in host cells interfered by pig BVDV-2 strain, and provided useful information to understand better the mechanism of BVDV-2 persistent infection in pigs.

Towards a peptide-based suspension array for the detection of pestivirus antibodies in swine.

Classical swine fever (CSF) is a highly contagious and lethal disease in swine. Serological tests for the diagnosis of CSF need not only to detect antibodies against CSFV, but also need to differentiate these from antibodies against other pestiviruses. To investigate the possibilities of specific peptide-based serology, various synthetic peptides that represent a well-described linear epitope of the CSFV E2 protein (TAVSPTTLR) were used to test the viability of a peptide-based suspension array for the detection of antibodies against pestiviruses in swine. The results show that N-terminally biotinylated peptides can bind to avidin conjugated beads, and function in detection of the corresponding monoclonal antibody WH303. There are indications that the length of the spacer between epitope and biotin affect the efficiency of the peptide-antibody interaction. A protocol was established that enables probing for antibodies in porcine sera, where neutravidin-blocking of serum and the use of empty control beads for normalization was crucial. With a set of porcine sera with antibodies against various pestiviruses, the proof of concept of a peptide-based suspension array for specific detection of antibodies against pestiviruses in porcine sera was demonstrated.

Comparison of 'HoBi'-like viral populations among persistent infected calves generated under experimental conditions and to inoculum virus.

Like other members from the Pestivirus genus, 'HoBi'-like pestiviruses cause economic losses for cattle producers due to both acute and persistent infections. The present study analyzed for the first time PI animals derived from a controlled infection with two different 'HoBi'-like strains where the animals were maintained under conditions where superinfection by other pestiviruses could be excluded. The sequence of the region coding for viral glycoproteins E1/E2 of variants within the swarms of viruses present in the PI calves and two viral inoculums used to generate them were compared. Differences in genetic composition of the viral swarms were observed suggesting that host factors can play a role in genetic variations among PIs. Moreover, PIs generated with the same inoculum showed amino acid substitutions in similar sites of the polyprotein, even in serum from PIs with different quasispecies composition, reinforcing that some specific sites in E2 are important for host adaptation.

Discovery of a novel putative atypical porcine pestivirus in pigs in the USA.

Pestiviruses are some of the most significant pathogens affecting ruminants and swine. Here, we assembled a 11 276 bp contig encoding a predicted 3635 aa polyprotein from porcine serum with 68 % pairwise identity to that of a recently partially characterized Rhinolophus affinis pestivirus (RaPV) and approximately 25-28 % pairwise identity to those of other pestiviruses. The virus was provisionally named atypical porcine pestivirus (APPV). Metagenomic sequencing of 182 serum samples identified four additional APPV-positive samples. Positive samples originated from five states and ELISAs using recombinant APPV Erns found cross-reactive antibodies in 94 % of a collection of porcine serum samples, suggesting widespread distribution of APPV in the US swine herd. The molecular and serological results suggest that APPV is a novel, highly divergent porcine pestivirus widely distributed in US pigs.

Structures and Functions of Pestivirus Glycoproteins: Not Simply Surface Matters.

Pestiviruses, which include economically important animal pathogens such as bovine viral diarrhea virus and classical swine fever virus, possess three envelope glycoproteins, namely Erns, E1, and E2. This article discusses the structures and functions of these glycoproteins and their effects on viral pathogenicity in cells in culture and in animal hosts. E2 is the most important structural protein as it interacts with cell surface receptors that determine cell tropism and induces neutralizing antibody and cytotoxic T-lymphocyte responses. All three glycoproteins are involved in virus attachment and entry into target cells. E1-E2 heterodimers are essential for viral entry and infectivity. Erns is unique because it possesses intrinsic ribonuclease (RNase) activity that can inhibit the production of type I interferons and assist in the development of persistent infections. These glycoproteins are localized to the virion surface; however, variations in amino acids and antigenic structures, disulfide bond formation, glycosylation, and RNase activity can ultimately affect the virulence of pestiviruses in animals. Along with mutations that are driven by selection pressure, antigenic differences in glycoproteins influence the efficacy of vaccines and determine the appropriateness of the vaccines that are currently being used in the field.

Host factors that interact with the pestivirus N-terminal protease, Npro, are components of the ribonucleoprotein complex.

UNLABELLED: The viral N-terminal protease N(pro) of pestiviruses counteracts cellular antiviral defenses through inhibition of IRF3. Here we used mass spectrometry to identify a new role for N(pro) through its interaction with over 55 associated proteins, mainly ribosomal proteins and ribonucleoproteins, including RNA helicase A (DHX9), Y-box binding protein (YBX1), DDX3, DDX5, eIF3, IGF2BP1, multiple myeloma tumor protein 2, interleukin enhancer binding factor 3 (IEBP3), guanine nucleotide binding protein 3, and polyadenylate-binding protein 1 (PABP-1). These are components of the translation machinery, ribonucleoprotein particles (RNPs), and stress granules. Significantly, we found that stress granule formation was inhibited in MDBK cells infected with a noncytopathic bovine viral diarrhea virus (BVDV) strain, Kyle. However, ribonucleoproteins binding to N(pro) did not inhibit these proteins from aggregating into stress granules. N(pro) interacted with YBX1 though its TRASH domain, since the mutant C112R protein with an inactive TRASH domain no longer redistributed to stress granules. Interestingly, RNA helicase A and La autoantigen relocated from a nuclear location to form cytoplasmic granules with N(pro). To address a proviral role for N(pro) in RNP granules, we investigated whether N(pro) affected RNA interference (RNAi), since interacting proteins are involved in RISC function during RNA silencing. Using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) silencing with small interfering RNAs (siRNAs) followed by Northern blotting of GAPDH, expression of N(pro) had no effect on RNAi silencing activity, contrasting with other viral suppressors of interferon. We propose that N(pro) is involved with virus RNA translation in the cytoplasm for virus particle production, and when translation is inhibited following stress, it redistributes to the replication complex. IMPORTANCE: Although the pestivirus N-terminal protease, N(pro), has been shown to have an important role in degrading IRF3 to prevent apoptosis and interferon production during infection, the function of this unique viral protease in the pestivirus life cycle remains to be elucidated. We used proteomic mass spectrometry to identify novel interacting proteins and have shown that N(pro) is present in ribosomal and ribonucleoprotein particles (RNPs), indicating a translational role in virus particle production. The virus itself can prevent stress granule assembly from these complexes, but this inhibition is not due to N(pro). A proviral role to subvert RNA silencing through binding of these host RNP proteins was not identified for this viral suppressor of interferon.

Genomic characterization of a bovine viral diarrhea virus 1 isolate from swine.

The SD0803 strain of the bovine viral diarrhea virus (BVDV) was isolated from a piglet in China in 2008 and has been classified as a novel subgenotype of BVDV-1. To describe the molecular features of this novel subgenotype, we sequenced and characterized the complete genome of the SD0803 virus. The genome is 12,271 bp in length and contains 5' and 3' untranslated regions (UTRs) that flank an open reading frame (ORF) encoding a 3,898-amino-acid polypeptide. The full-length genome of the SD0803 strain shares 78.8% to 83.3% identity with those of other BVDV-1 strains, 70.0% to 70.7% identity with those of BVDV-2 strains, and less than 67.6% identity with those of other pestiviruses. The highest level of shared identity was 83.3% between the complete SD0803 genome and that of the ZM-95 strain of BVDV-1. Phylogenetic analysis of the 5' UTR and the coding sequence for the N-terminal protease fragment of the SD0803 polyprotein indicated that the SD0803 virus is a member of the novel subgenotype BVDV-1q, isolates of which have been identified recently in dairy cattle and camels in China.