Inhibition of caspase-1-dependent apoptosis suppresses peste des petits ruminants virus replication

Background@#Peste des petits ruminants (PPR), caused by the PPR virus (PPRV), is an acute and fatal contagious disease that mainly infects goats, sheep, and other artiodactyls.Peripheral blood mononuclear cells (PBMCs) are considered the primary innate immune cells. @*Objectives@#PBMCs derived from goats were infected with PPRV and analyzed to detect the relationship between PPRV replication and apoptosis or the inflammatory response. @*Methods@#Quantitative real-time polymerase chain reaction was used to identify PPRV replication and cytokines expression. Flow cytometry was conducted to detect apoptosis and the differentiation of CD4+ and CD8+T cells after PPRV infection. @*Results@#PPRV stimulated the differentiation of CD4+ and CD8+ T cells. In addition, PPRV induced apoptosis in goat PBMCs. Furthermore, apoptosis and the inflammatory response induced by PPRV could be suppressed by Z-VAD-FMK and Z-YVAD-FMK, respectively.Moreover, the virus titer of PPRV was attenuated by inhibiting caspase-1-dependent apoptosis and inflammation. @*Conclusions@#This study showed that apoptosis and the inflammatory response play an essential role in PPR viral replication in vitro, providing a new mechanism related to the cell host response.

Selection and identification of singledomain antibody against Peste des Petits Ruminants virus

Background@#Peste des petits ruminants (PPR) is an infectious disease caused by the peste des petits ruminants virus (PPRV) that mainly produces respiratory symptoms in affected animals, resulting in great losses in the world's agriculture industry every year. Singledomain variable heavy chain (VHH) antibody fragments, also referred to as nanobodies, have high expression yields and other advantages including ease of purification and high solubility. @*Objectives@#The purpose of this study is to obtain a single-domain antibody with good reactivity and high specificity against PPRV. @*Methods@#A VHH cDNA library was established by immunizing camels with PPRV vaccine, and the capacity and diversity of the library were examined. Four PPRV VHHs were selected, and the biological activity and antigen-binding capacity of the four VHHs were identified by western blot, indirect immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) analyses. ELISA was used to identify whether the four VHHs were specific for PPRV, and VHH neutralization tests were carried out. ELISA and western blot analyses were used to identify which PPRV protein was targeted by VHH2. @*Results@#The PPRV cDNA library was constructed successfully. The library capacity was greater than 2.0 × 106 cfu/mL, and the inserted fragment size was approximately 400 bp to 2000 bp. The average length of the cDNA library fragment was about 1000 bp, and the recombination rate was approximately 100%. Four single-domain antibody sequences were selected, and proteins expressed in the supernatant were obtained. The four VHHs were shown to have biological activity, close affinity to PPRV, and no cross-reaction with common sheep diseases. All four VHHs had neutralization activity, and VHH2 was specific to the PPRV M protein. @*Conclusions@#The results of this preliminary research of PPRV VHHs showed that four screened VHH antibodies could be useful in future applications. This study provided new materials for inclusion in PPRV research.

Selection and identification of singledomain antibody against Peste des Petits Ruminants virus

Background@#Peste des petits ruminants (PPR) is an infectious disease caused by the peste des petits ruminants virus (PPRV) that mainly produces respiratory symptoms in affected animals, resulting in great losses in the world's agriculture industry every year. Singledomain variable heavy chain (VHH) antibody fragments, also referred to as nanobodies, have high expression yields and other advantages including ease of purification and high solubility. @*Objectives@#The purpose of this study is to obtain a single-domain antibody with good reactivity and high specificity against PPRV. @*Methods@#A VHH cDNA library was established by immunizing camels with PPRV vaccine, and the capacity and diversity of the library were examined. Four PPRV VHHs were selected, and the biological activity and antigen-binding capacity of the four VHHs were identified by western blot, indirect immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) analyses. ELISA was used to identify whether the four VHHs were specific for PPRV, and VHH neutralization tests were carried out. ELISA and western blot analyses were used to identify which PPRV protein was targeted by VHH2. @*Results@#The PPRV cDNA library was constructed successfully. The library capacity was greater than 2.0 × 106 cfu/mL, and the inserted fragment size was approximately 400 bp to 2000 bp. The average length of the cDNA library fragment was about 1000 bp, and the recombination rate was approximately 100%. Four single-domain antibody sequences were selected, and proteins expressed in the supernatant were obtained. The four VHHs were shown to have biological activity, close affinity to PPRV, and no cross-reaction with common sheep diseases. All four VHHs had neutralization activity, and VHH2 was specific to the PPRV M protein. @*Conclusions@#The results of this preliminary research of PPRV VHHs showed that four screened VHH antibodies could be useful in future applications. This study provided new materials for inclusion in PPRV research.

Suckling mouse model establishment of myocarditis induced by foot-and-mouth disease vi rus / 中国人兽共患病学报

Interactions between FMDV and cardiac cells are multifaceted and complex ,these interactions leads to pro-teins alterations in cardiac cells inevitably .To understand the pathogenesis of myocarditis after FMDV infection in mice ,the suckling mouse model for myocarditis induced by foot-and-mouth disease virus (FMDV) was established in this study .Suckling mice within 3 days old was selected to infect by FMDV .Myocarditis caused by FMDV in suckling mice was confirmed with clinical symptom monitor .The observation of Hematoxylin and eosin stain (H&E stain) and transmission electron microscopy (TEM) were performed after samples processing .According to conventional polymerase chain reaction (PCR) methods ,prim-ers of VP1 gene was designed ,synthesised and specific FMDV VP1 gene was amplified from the heart muscle of suckling mice . The results indicated that suckling mice appeared low spirit condition ,dyspnea ,and dull reaction within 36 hours after chal-lenge with FMDV .Infiltration of inflammatory cells and dissolution of myocardial fibers were observed with H&E stain and TEM .Special target gene of FMDV was amplified from the heart of infected group .Obvious inflammation in the heart of suck-ling mice caused by FMDV was observed .It's suggested that suckling mouse model for myocarditis induced by FMDV was es-tablished successfully ,which would lay the foundation for researches of myocarditis mechanism in young cloven-hoofed ani-mals .

Application of GP5 Protein to Develop Monoclonal Antibody against Porcine Reproductive and Respiratory Syndrome Virus / 中国病毒学·英文版

In this study,a panel of monoclonal antibodies (mAbs) against Porcine reproductive and respiratory syndrome virus(PRRSV),named as 8C9 and4B4,were produced by fusing SP2/0 myeloma cells and spleen cells of BALB/c mice immunized with the PRRSV (TCID50=5.5),screened by the indirect ELISA and subjected to several limiting dilutions.mAbs were then identified by biological characterization.Among the two fusion cell strains,8C9 belonged to the IgG1 subclass and 4B4 belonged to the IgG2a subclass.The titers in cell culture supernatant and abdomen liquor reached to 1:104and 1:105,respectively.The specificity test indicated that the two cells had specific reactions for the PRRSV and GP5 protein respectively,and no reaction with Classical swine fever virus (CSFV) or Swine vesicular disease virus (SVDV).The molecular weights of the heavy chain and light chain were about 45.0 kDa and 25.0 kDa,respectively.In neutralization activity tests,the results showed that the prepared mAb 4B4 can protect 50% of cells with no CPE in dilution up to 1:512,but mAB 8C9 has no neutralization activities to PRRSV.

Indirect ELISA with Recombinant GP5 for Detecting Antibodies to Porcine Reproductive and Respiratory Syndrome Virus / 中国病毒学·英文版

Porcine reproductive and respiratory syndrome is caused by the PRRS virus(PRRSV), which has six structural proteins(GP2, GP3, GP4, GP5, M and N). GP5 and N protein are important targets for serological detection by enzyme-linked immunosorbent assay(ELISA)and other methods. Toward this goal, we developed an indirect ELISA with recombinant GP5 antigens and this method was validated by comparison to the LSI PRRSV-Ab ELISA kit. The results indicated that the optimal concentration of coated recombinant antigen was 0.2 μg/well for a serum dilution of 1:40. The rate of agreement with the LSI PRRSV-Ab kit was 88.7%(266/300). These results support the potential use of recombinant GP5 as an antigen for indirect ELISA to detect PRRSV antibodies in pigs.

An ELISA Based on a Truncated Soluble ORF2 Protein for the Detection of PCV2 Antibodies in Domestic Pigs / 中国病毒学·英文版

Postweaning multisystemie wasting syndrome (PMWS) is an important swine disease that is closely associated with porcine circovirus type 2 (PCV2). The capsid protein (Cap protein) is a major structural protein that has at least three immunoreactive regions, and it can be a suitable candidate antigen for detecting the specific antibodies of a PCV2 infection. In the present study, an indirect enzyme-linked immunosorbent assay (TcELISA)based on a truncated soluble Cap protein produced in Escherichia coli (E.coli) was established and validated for the diagnostic PCV2 antibodies in swine. The TcELISA was validated by comparison with an indirect immunofluorescence assay (IIFA). The diagnostic sensitivity (DSN), specificity (DSP), and accuracy of the TcELISA were 88.6%, 90.7% and 89.4%, respectively. The agreement rate was 89.38% between results obtained with TcELISA and IIFA on 113 field sera. A cross-reactivity assay showed that the method was PCV2-specific by comparison with other sera of viral disease. Therefore ,the TcELISA will be helpful for the development of a reliable serology diagnostic test for large scale detection of PCV2 antibodies and for the evaluation of vaccine against PCV2 in swine.

Expression and Immunological Analysis of Capsid Protein Precursor of Swine Vesicular Disease Virus HK/70 / 中国病毒学·英文版

VP1, a capsid protein of swine vesicular disease virus, was cloned from the SVDV HK/70 strain and inserted into retroviral vector pBABE puro, and expressed in PK15 cells by an retroviral expression system. The ability of the VP1 protein to induce an immune response was then evaluated in guinea pigs. Western blot and ELISA results indicated that the VP1 protein can be recognized by SVDV positive serum, Furthermore,anti-SVDV specific antibodies and lymphocyte proliferation were elicited and increased by VP1 protein after vaccination. These results encourage further work towards the development of a vaccine against SVDV infection.

Genetic Variation Analyses of nsp2 Gene of PRRSV in Ningxia Hui Autonomous Region of China / 中国病毒学·英文版

To gain a better understanding of the genetic diversity and evolution of PRRSV in the Ningxia Hui Nationality Autonomous Region (Ningxia) of China, the nsp2 genes from a series of PRRSV strains collected from the region in 2007 were partially sequenced. These sequences were then analyzed along with the classical strain (ch-la) and two other epidemic strains SD (3) and SD2006. Comparison of the nucleotide sequence with ch-la indicated that nsp2 genes of seventeen Ningxia isolates (NX strain) have deletions of 87 nucleotides. Sequence analysis indicated that homology between the Ningxia strain and ch-la was 60.3%-79.9% in the nucleotide sequence, and homology between the NX strains and SD strains was 80.3%-98.8% in the nucleotide sequence. The nsp2 genes of the seventeen isolates had 74.9%-100% nucleotide sequence identities with each other. This study was undertaken to assess the regional variation of prevalent PRRSV and to establish a sequence database for PRRSV molecular epidemiological studies.

Expression of Major Antigen Domains of Gene of E2 CSFV and Analysis of its Immunological Activity / 中国病毒学·英文版

E2 is an envelope glycoprotein of Classical swine fever virus (CSFV) and contains sequential neutralizing epitopes to induce virus-neutralizing antibodies and mount protective immunity in the natural host. In this study, four antigen domains (ABCD) of the E2 gene was cloned from CSFV Shimen strain into the retroviral vector pBABE puro and expressed in eukaryotic cell (PK15) by an retroviral gene expression system, and the activity of recombinant E2 protein to induce immune responses was evaluated in rabbits. The results indicated that recombinant E2 protein can be recognized by fluorescence antibodies of CSFV and CSFV positive serum (Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China) using Western blot, indirect immunofluorescence antibody test (IFAT) and ELISA, Furthermore, anti-CSFV specific antibodies and lymphocyte proliferation were elicited and increased by recombinant protein after vaccination. In the challenge test, all of rabbits vaccinated with recombinant protein and Chinese vaccine strain (C-strain) were fully protected from a rabbit spleen virus challenge. These results indicated that a retroviral-based epitope-vaccine carrying the major antigen domains of E2 is able to induce high level of epitope-specific antibodies and exhibits similar protective capability with that induced by the C-strain, and encourages further work towards the development of a vaccine against CSFV infection.

Amplification and Characterization of Bull Semen Infected Naturally with Foot-and-mouth Disease Virus Type Asial by RT-PCR / 中国病毒学·英文版

To investigate the security of semen biologically, 15 bull semen samples were collected (of which 5 exhibited clinical signs of Foot-and-mouth disease) and identified by RT-PCR and virus isolation. The results indicated that the semen of the infected bulls were contaminated by Foot-and-mouth disease virus (FMDV), but FMDV was not detected in semen samples from those bulls not showing clinical signs of Foot-and-mouth disease (FMD). This is the first report of the presence of FMDV in bull semen due to natural infection in China. The analysis of the partial sequence of the VP1 gene showed that the virus strain isolated from semen has 97.9% identity with the virus isolated from vesicular liquid of infected bulls showing typical signs of FMD and belonged to the same gene sub-group.

Cloning of foot-and-mouth disease virus integrin receptor beta1 subunit and antibody production to its ligand-binding domain / 生物工程学报

We produced beta1 gene which is about 2400 bp by reverse transcription polymerase chain reaction (RT-PCR) from bovine trachea, reclaimed and purified, then cloned the amplified fragment to pGEM-T easy vector, confirmed by sequencing. The immune-dominant epitope of beta1 gene was chosen by computer analysis and then syncretized ligand-binding domain from 346 bp to 843 bp of ecytoplasm with six histidine, expressed LBD protein massly in E. coli BL21 (DE3), and identified by SDS-PAGE. The fusion protein was purified with Ni-NTA affinity chromatography and immunized New Zealand rabbits preparing of its polyclonal antibody, the specific antibody titer was above 1:12,800 detected by indirect ELISA, the result of Western blot showed that this antibody could be recognized by LBD fusion protein.

Establishment of IBRS-2 Cell Line Stably Expressing T7 RNA Polymerase and Recovery of SVDV From IBRST7 Cells / 生物化学与生物物理进展

The bacteriophage T7 RNAP gene was amplified via PCR from -lysogen DE3, and the gene was cloned into pBABEpuro retrovial vector, a recombinant plasmid named as pT7BABEpuro was constructed and sequenced. Then the pT7BABEpuro and pVSV-G plasmids were cotransfected into GP2-293 packaging cells by liposomese, some pseudotype viruses were ingathered and transfected into IBRS-2 cell under polybrene. The IBRS-2 cell was propagated in DMEM with puromycin. The genome extraction from the cells transfected different times, the T7 RNAP gene was amplified from the genome by PCR, the mRNA of T7 RNAP protein expressed in IBRST7 cells was analyzed by RT-PCR, respectively, the results showed the T7 RNAP gene had been integrated into the chromosome of IBRS-2 cell and expressed stably at high level. To study whether T7 RNAP is of transcriptional activity in the established IBRST7 cell line, a plasmid pIERS-EGFP-ET with a reporter gene (EGFP) under control of the T7 promoter was constructed. IRES element from FMDV (for CAP-independent translation) was cloned into plasmid pET-43.1a-c(+) downstream of the T7 promoter sequence, then EGFP gene was cloned in frame downstream of the AUG codon of the FMDV IRES, resulting in the plasmid. IBRST7 cells were transfected with plasmid pIERS-EGFP-ET using lipfection, EGFP was expressed, the results showed the T7 RNAP in IBRST7 cells has transcriptional activity. IBRST7 cell line was directly transfected with linearized full-length cDNA of swine vesicular disease virus (SVDV) HK/70, infectious SVDV was efficiently recovered from the cDNA. The reverse genetic procedure is simplified to a faster, one step protocol to recover RNA virus and will be useful to understand the mechanisms of molecular pathology of RNA virus and develop effective vaccines.

Immunological analysis of the swine vesicular disease virus (SVDV) recombinant P1 protein in Guinea pigs / 中国免疫学杂志

Objective:To investigate the immunogeneicity of a subunit vaccine of capsid protein precursor(P1) of swine vesicular diseas(SVD).Methods:In this study,the guinea pigs were immunized with the home-made antigen,T-lymphocyte proliferation response,blocking ELISA and micro-neutralization assay were used to detect the effect of the immunized responses in guinea pigs.Results:The results indicated that a retroviral-based vaccine carrying the capsid protein precursor(P1) of SVD was able to elicit strong SVDV-specific humoral immune responses in guinea pigs.Conclusion:It encourages further work towards the development of a vaccine against SVDV infection.