The deltacoronavirus is a new member of the subfamily Coronaviridae of the family Coronaviridae. Deltacoronaviruses can infect birds and mammals. Deltacoronaviruses were detected in early 2007 in Asian leopard cats and Chinese ferret badgers. In 2014, porcine deltacoronavirus (PDCoV) infection spread rapidly in the USA. Moreover, cell culture-adapted PDCoV has been obtained from infected piglets. Animal experiments have confirmed that the isolated PDCoV is highly pathogenic and causes severe diarrhea in piglets. Thus, the PDCoV can be considered to be a good model to study the deltacoronavirus. In this review, we discuss the etiology, epidemiology, pathogenicity, culture, and diagnostic methods of the PDCoV.
Animals ; Coronavirus ; classification ; genetics ; isolation & purification ; Coronavirus Infections ; veterinary ; virology ; Diarrhea ; veterinary ; virology ; Phylogeny ; Swine ; Swine Diseases ; virology

An indirect porcine epidemic diarrhea (PED) virus (PEDV) enzyme-linked immunosorbent assay (ELISA) was compared with the serum neutralization (SN) test by testing 46 samples from experimentally infected sows, 73 samples from naive sows, and 1, 024 field sow samples from 48 commercial swine farms of undefined PED status. The SN test and the ELISA were performed using PEDV, KPEDV-9 strain. Viral proteins as a coating antigen of PEDV ELISA were extracted from the cytoplasm of PEDV-infected Vero cells using a non-ionic detergent, Triton X-100, and a simple protocol of PEDV ELISA was followed. The presence of antibodies in these experimental samples was confirmed by SN and ELISA in which the sensitivity of the ELISA was 89.1%, and the corresponding specificity was 94.5%. On testing 1, 024 field samples, an overall agreement of 84.2% was generated between the SN and ELISA. This study demonstrates that the PEDV ELISA is a useful serodiagnostic screening test at herd level for detecting swine antibodies against PEDV.
Animals ; Antibodies, Viral/blood ; Coronavirus Infections/diagnosis/*veterinary/virology ; Diarrhea/diagnosis/*veterinary ; Enzyme-Linked Immunosorbent Assay/veterinary ; Female ; Neutralization Tests/veterinary ; Sensitivity and Specificity ; Swine ; Swine Diseases/diagnosis/*virology

Porcine epidemic diarrhea virus (PEDV) causes an acute enteritis in pigs of all ages, often fatality for neonates. PEDV occupies an intermediate position between two well characterized members of the coronavirus group I, human coronavirus (HCoV-229E)and transmissible gastroenteritis virus (TGEV) which uses aminopeptidase N (APN), a 150 kDa protein, as their receptors. However, the receptor of the PEDV has not been identified yet. A virus overlay protein binding assay (VOPBA) was used to identify PEDV binding protein in permissive cells. The binding ability of PEDV to porcine APN (pAPN) and the effects of pAPN on infectivity of PEDV in Vero cells were also investigated. VOPBA identified a 150 kDa protein, as a putative PEDV receptor in enterocytes and swine testicle (ST) cells. Further the PEDV binding to pAPN was blocked by anti-pAPN and pAPN enhanced PEDV infectivity in Vero cells. In conclusion, these results suggested that pAPN may act as a receptor of PEDV.
Animals ; Antigens, CD13/*metabolism ; Cercopithecus aethiops ; Coronavirus/*metabolism ; Coronavirus Infections/*veterinary/virology ; Digestive System Diseases/metabolism/*veterinary/virology ; Enterocytes/enzymology/metabolism/virology ; Enzyme-Linked Immunosorbent Assay/veterinary ; Male ; Protein Binding ; Receptors, Virus/*metabolism ; Swine ; Swine Diseases/metabolism/*virology ; Vero Cells

Porcine epidemic diarrhea (PED) is a major disease of pigs that inflicts heavy losses on the global pig industry. The etiologic agent is the porcine epidemic diarrhea virus (PEDV), which is assigned to the genus Alphacoronavirus in the family Coronaviridae. This review consists of five parts, the first of which provides a brief introduction to PEDV and its epidemiology. Part two outlines the passive immunity in new born piglets and the important role of colostrum, while the third part summarizes the characteristics of the immune systems of pregnant sows, discusses the concept of the "gut-mammary gland-secretory IgA(sIgA) axis" and the possible underpinning mechanisms, and proposes issues to be addressed when designing a PEDV live vaccine. The final two parts summarizes the advances in the R&D of PEDV vaccines and prospects future perspectives on prevention and control of PEDV, respectively.
Animals ; Antibodies, Viral ; Coronavirus Infections/veterinary* ; Female ; Immunization ; Porcine epidemic diarrhea virus ; Pregnancy ; Swine ; Swine Diseases/prevention & control* ; Viral Vaccines

Despite the existence of an active vaccination program, recently emerged strains of nephropathogenic infectious bronchitis virus (IBV) in Korea have caused significant economic losses in the poultry industry. In this study, we assessed the pathogenic and antigenic characteristics of a K-IIb type field strain of IBV that emerged in Korea since 2003, such as Kr/Q43/06. Specific pathogen free 1-week-old chickens exhibited severe respiratory symptoms (dyspnea) and nephropathogenic lesions (swollen kidneys with nephritis and urate deposits) following challenge with the recent IBV field strain. The antigenic relatedness (R value), based on a calculated virus neutralization index, of the K-IIb type field strain and K-IIa type strain KM91 (isolated in 1991) was 30%, which indicated that the recent strain, Kr/Q43/06, is a new variant that is antigenically distinct from strain KM91. This report is the first to document the emergence of a new antigenic variant of nephropathogenic IBV in chicken from Korea.
Animals ; Antigens, Viral ; *Chickens ; Coronavirus Infections/epidemiology/*veterinary/virology ; Infectious bronchitis virus/classification/*pathogenicity ; Korea ; Nephritis/*veterinary/virology ; Poultry Diseases/*virology ; Specific Pathogen-Free Organisms ; Virulence

The aim of this study was to develop a blocking enzyme-linked immunosorbent assay (bELISA) based on a biotinylated nanobody target the S1 protein of porcine epidemic diarrhea virus (PEDV) for detecting the anti-PEDV antibodies and evaluating the immune effect of the vaccine. The gene encoding the single-domain antibody sdAb3 target the PEDV S1 protein was amplified and the Avitag sequence was fused at its 3'-end. The PCR product was cloned into the expression vector pET-21b for expression and purification of the sdAb3-Avitag protein. The purified sdAb3-Avitag fusion protein was biotinylated and its activity was determined. Using the recombinant S1 protein as a coating antigen, a bELISA was established and optimized. Serum samples were tested in parallel by the bELISA and a commercial kit. The recombinant vector pET21b-sdAb3-Avitag was constructed to express the tagged sdAb3. After induction for expression, the biotin-labeled sdAb3 (sdAb3-Biotin) with high purity and good activity was obtained. For the optimized bELISA, the coating concentration of the S1 protein was 200 ng/well, the serum dilution was 1:2 and incubated for 2 h, the dilution ratio of the biotinylated sdAb3 was 1:8 000 and incubated for 30 min, the dilution of the enzyme-labeled antibody was 1:5 000 and incubated for 30 min. The bELISA had no cross reaction with the sera of major porcine viruses including transmissible gastroenteritis virus, porcine reproductive and respiratory syndrome virus and showed good specificity and reproducibility. For a total of 54 porcine serum samples tested, the overall compliance rate of the bELISA with a commercial kit was 92.56%. This study developed a rapid and reliable bELISA method, which can be used for serosurveillance and vaccine evaluation for PEDV.
Animals ; Antibodies, Viral ; Coronavirus Infections/veterinary* ; Enzyme-Linked Immunosorbent Assay ; Porcine epidemic diarrhea virus/genetics* ; Reproducibility of Results ; Sensitivity and Specificity ; Single-Domain Antibodies ; Swine ; Swine Diseases

To investigate whether the engineered Lactobacillus plantarum expressing the porcine epidemic diarrhea virus (PEDV) S1 gene can protect animals against PEDV, guinea pigs were fed with recombinant L. plantarum containing plasmid PVE5523-S1, with a dose of 2×10⁸ CFU/piece, three times a day, at 14 days intervals. Guinea pigs fed with wild type L. plantarum and the engineered L. plantarum containing empty plasmid pVE5523 were used as negative controls. For positive control, another group of guinea pigs were injected with live vaccine for porcine epidemic diarrhea and porcine infectious gastroenteritis (HB08+ZJ08) by intramuscular injection, with a dose of 0.2 mL/piece, three times a day, at 14 days intervals. Blood samples were collected from the hearts of the four groups of guinea pigs at 0 d, 7 d, 14 d, 24 d, 31 d, 41 d and 48 d, respectively, and serum samples were isolated for antibody detection and neutralization test analysis by enzyme-linked immunosorbent assay (ELISA). The spleens of guinea pigs were also aseptically collected to perform spleen cells proliferation assay. The results showed that the engineered bacteria could stimulate the production of secretory antibody sIgA and specific neutralizing antibody, and stimulate the increase of IL-4 and IFN-γ, as well as the proliferation of spleen cells. These results indicated that the engineered L. plantarum containing PEDV S1 induced specific immunity toward PEDV in guinea pigs, which laid a foundation for subsequent oral vaccine development.
Animals ; Antibodies, Viral ; Coronavirus Infections/veterinary* ; Guinea Pigs ; Lactobacillus plantarum/genetics* ; Porcine epidemic diarrhea virus/genetics* ; Swine ; Swine Diseases ; Viral Vaccines/genetics*

We wished to ascertain the prevalence as well as the genetic and antigenic variation of infectious bronchitis viruses (IBVs) circulating in the Guangxi Province of China in recent years. The S1 gene of 15 IBV field isolates during 2012-2013 underwent analyses in terms of the similarity of amino-acid sequences, creation of phylogenetic trees, recombination, and serologic identification. Similarities in amino-acid sequences among the 15 isolates of the S1 gene were 54.3%-99.6%, and 43.3%-99.3% among 15 isolates and reference strains. Compared with the vaccine strain H120, except for GX-YL130025, the other 14 isolates showed a lower similarity of amino-acid sequences of the S1 gene (65.1-81.4%). Phylogenetic analyses of the S1 gene suggested that 15 IBV isolates were classified into eight genotypes, with the predominant genotype being new-type II. Recombination analyses demonstrated that the S1 gene of the GX-NN130048 isolate originated from recombination events between vaccine strain 4/91 and a LX4-like isolate. Serotyping results suggested that seven serotypes prevailed during 2012-2013 in Guangxi Province, and that only one isolate was consistent with the vaccine strain H120 in serotype (which has been used widely in recent years). The serotype of recombinant isolate GX-NN130048 was different from those of its parent strains. These results suggested that not only the genotype, but also the serotype of IBV field isolates in Guangxi Province had distinct variations, and that increasing numbers of genotypes and serotypes are in circulation. We showed that recombination events can lead to the emergence of new serotypes. Our study provides new evidence for understanding of the molecular mechanisms of IBV variations, and the development of new vaccines against IBVs.
Animals ; Antibodies, Viral ; blood ; Chickens ; China ; Coronavirus Infections ; blood ; veterinary ; virology ; Genetic Variation ; Genotype ; Infectious bronchitis virus ; classification ; genetics ; immunology ; isolation & purification ; Molecular Sequence Data ; Phylogeny ; Poultry Diseases ; blood ; virology ; Sequence Homology, Amino Acid ; Spike Glycoprotein, Coronavirus ; chemistry ; genetics ; immunology

The entire S1 protein gene of five infectious bronchitis (IB) vaccine strains (JAAS, IBN, Jilin, J9, H120) used in China were compared with that of the IB field isolate CK/CH/LDL/97 I present in China. The nucleotide and deduced amino acid similarities between the five IB vaccine strains and the field strain, CK/CH/LDL/97 I, were not more than 76.4% and 78.7%, respectively. Phylogenetic analysis based on the S1 gene showed that the vaccine strains and the field strain belonged to different clusters and had larger evolutionary distances, indicating that they were of different genotypes. The five vaccine strains were used for protection test against challenge of the field isolate CK/CH/LDL/97 I. The chickens inoculated with five vaccine strains showed morbidity as high as 30%-100% after challenged with the CK/CH/ LDL/97 I strain. The organ samples at 5 days post challenge showed that the viral detection rates were 50%-90% and 10%-30% for trachea and kidney, respectively. The live attenuated vaccines only provided partial protection to the vaccinated chickens against heterologous IBV infection, CK/CH/LDL/97 I.
Animals ; Antibodies, Viral ; blood ; Chickens ; virology ; Coronavirus Infections ; prevention & control ; veterinary ; Infectious bronchitis virus ; classification ; genetics ; immunology ; isolation & purification ; Membrane Glycoproteins ; genetics ; Phylogeny ; Poultry Diseases ; prevention & control ; Spike Glycoprotein, Coronavirus ; Vaccines, Attenuated ; immunology ; Viral Envelope Proteins ; genetics ; Viral Vaccines ; immunology

To explore the expression potential of heterogeneous genes using the backbone of infectious bronchitis virus (IBV) Beaudette strain, the ectodomain region of the Spike gene (1,302 bp) of IBV H120 strain was amplified by RT-PCR and replaced into the corresponding location of the IBV Beaudette strain full-length cDNA. This recombinant was designated as BeauR-H120(S1). BeauR-H120(S1) was directly used as the DNA template for the transcription of viral genomic RNA in vitro. Then, the transcription product was transfected into Vero cells by electroporation. At 48 h post-transfection, the transfected Vero cells were harvested, and passaging continued. A syncytium was not observed until the recombinant virus had passed through four passages. The presence of rBeau-H120(S1) was verified by the detection of the replaced ectodomain region of the H120 Spike gene using RT-PCR. Western blot analysis of rBeau-H120 (S1)-infected Vero cell lysates demonstrated that the nucleocapsid (N) protein was expressed, which implied that rBeau-H120(S1) could propagate in Vero cells. The TCIDs0 and EIDs0 data demonstrated that the titer levels of rBeau-H120(S1) reached 10(590+/-0.22)TCID50/mL and 10(6.13+/-0.23)EID50/mL in Vero cells and 9-day-old SPF chicken embryos, respectively. Protection studies showed that the percentage of antibody-positive chickens, which were vaccinated with rBeau-H120(S1) at 7 days after hatching, rose to 90% at 21 days post-inoculation. Inoculation provided an 85% rate of immune protection against a challenge of the virulent IBV M41 strain (103EID50/chicken). This recombinant virus constructed using reverse genetic techniques could be further developed as a novel genetic engineering vaccine against infectious bronchitis.
Animals ; Cercopithecus aethiops ; Chick Embryo ; Chickens ; Coronavirus Infections ; veterinary ; virology ; Infectious bronchitis virus ; chemistry ; genetics ; growth & development ; metabolism ; Poultry Diseases ; virology ; Protein Structure, Tertiary ; Spike Glycoprotein, Coronavirus ; chemistry ; genetics ; metabolism ; Transfection ; Vero Cells