Protective effects of the secondary metabolites from Quercus salicina Blume against gentamicin-induced nephrotoxicity in zebrafish (Danio rerio) model.

To reveal the protective effect on the nephrotoxicity of Quercus salicina Blume(QS), a traditional medicine for the treatment of urolithiasis, the 50 % ethanol extract from the branches and leaves of QS was chemically studied by systematic solvent extraction and HPLC chromatography. Two phenolic acids and three flavonoids were identified by nuclear magnetic resonance spectroscopy, namely Ferulic acid (1), p-Hydroxycinnamic acid (2), Hesperidin (3), Formononetin (4), and Quercetin (5). At the same time, the gentamicin-induced nephrotoxicity of zebrafish was used as a model for the first time. The antioxidant activity of these derivatives with good antioxidant activity screened from free radical scavenging experiments in vitro (DPPH and ABTS) was evaluated in vivo, including protein levels (LPO, NO, GSH, and SOD), kidney injury factor (KIM-1), zebrafish kidney pathology and real-time PCR. The results showed that metabolites 1, 3, and 5 had strong antioxidant activity, and oxidative stress in renal tissue was significantly reduced; KIM-1, TNF-α, and IL-6 mRNA expression in a dose-dependent manner, which preliminarily revealed the protective effect of the secondary metabolites of QS on nephrotoxicity, and preliminarily discussed the structure-activity relationship. This study provides an experimental basis for further exploring the mechanism of QS in the kidney.

High prevalence and genetic diversity of porcine bocaviruses in pigs in the USA, and identification of multiple novel porcine bocaviruses.

Viruses in the genus Bocavirus are associated with respiratory and enteric disease in dogs and cattle. In addition, novel porcine bocaviruses (PBoVs) have been identified in domestic and wild pigs in recent years, but are of unknown relevance to date. The objectives of this study were to determine the prevalence ra tes and genetic diversity of PBoVs in pigs in the USA. Using newly established multiplex real-time PCR assays, 385 lung, lymph node, serum and faecal samples from pigs with various disease conditions were investigated. A high PBoV prevalence rate ranging from 21.3 to 50.8 % was identified in the investigated samples and often two or more PBoV species were detected in the same sample. Cloning and sequencing analysis of the partial non-structural protein NS1 and the capsid proteins VP1 and VP2 of DNA samples positive for PBoV groups 1 (n = 6), 2 (n = 16) and 3 (n = 42), including subgroups 3A, 3B or 3C, revealed a high genetic diversity especially for the PBoV G3 VP2 gene, whereas the PBoV group 1 VP1 gene displayed a low nucleotide polymorphism. Using primer walking, 18 partial or nearly complete genomes of PBoVs were obtained and six of the 18 nearly complete genomes represented novel PBoV species. Recombination analysis using partial NS1, VP1 and VP2 genes and the nearly complete genomes indicated possible recombination events within and between PBoVs. Further studies will be required to reveal the possible pathogenic role of these diverse PBoVs.

Concurrent porcine circovirus type 2a (PCV2a) or PCV2b infection increases the rate of amino acid mutations of porcine reproductive and respiratory syndrome virus (PRRSV) during serial passages in pigs.

Porcine reproductive and respiratory syndrome virus (PRRSV) has a high degree of genetic and antigenic variability. The purpose of this study was to determine if porcine circovirus type 2 (PCV2) infection increases genetic variability of PRRSV during serial passages in pigs and to determine if there is a difference in the PRRSV mutation rate between pigs concurrently infected with PCV2a or PCV2b. After 8 consecutive passages of PRRSV alone (group 1), PRRSV with PCV2a (group 2), or PCV2b (group 3) in pigs, the sequences of PRRSV structural genes for open reading frame (ORF) 5, ORF6, ORF7 and the partial non-structural protein gene (Nsp) 2 were determined. The total number of identified amino acid mutations in ORF5, ORF6, ORF7 and Nsp2 sequences was 30 for PRRSV infection only, 63 for PRRSV/PCV2a concurrent infection, and 77 for PRRSV/PCV2b concurrent infection when compared with the original VR2385 virus used to infect the passage 1 pigs. Compared to what occurred in pigs infected with PRRSV only, the mutation rates in ORF5 and ORF6 were significantly higher for concurrent PRRSV/PCV2b infected pigs. The PRRSV/PCV2a pigs had a significantly higher mutation rate in ORF7. The results from this study indicated that, besides ORF5 and Nsp2, the PRRSV structural genes ORF6 and ORF7 were shown to mutate at various degrees when the PRRSV was passaged over time in vivo. Furthermore, a significantly higher mutation rate of PRRSV was observed when pigs were co-infected with PCV2 highlighting the importance of concurrent infections on PRRSV evolution and control.

Foot-and-mouth disease virus-like particles produced by a SUMO fusion protein system in Escherichia coli induce potent protective immune responses in guinea pigs, swine and cattle.

Foot-and-mouth disease virus (FMDV) causes a highly contagious infection in cloven-hoofed animals. The format of FMD virus-like particles (VLP) as a non-replicating particulate vaccine candidate is a promising alternative to conventional inactivated FMDV vaccines. In this study, we explored a prokaryotic system to express and assemble the FMD VLP and validated the potential of VLP as an FMDV vaccine candidate. VLP composed entirely of FMDV (Asia1/Jiangsu/China/2005) capsid proteins (VP0, VP1 and VP3) were simultaneously produced as SUMO fusion proteins by an improved SUMO fusion protein system in E. coli. Proteolytic removal of the SUMO moiety from the fusion proteins resulted in the assembly of VLP with size and shape resembling the authentic FMDV. Immunization of guinea pigs, swine and cattle with FMD VLP by intramuscular inoculation stimulated the FMDV-specific antibody response, neutralizing antibody response, T-cell proliferation response and secretion of cytokine IFN-γ. In addition, immunization with one dose of the VLP resulted in complete protection of these animals from homologous FMDV challenge. The 50% protection dose (PD50) of FMD VLP in cattle is up to 6.34. These results suggest that FMD VLP expressed in E. coli are an effective vaccine in guinea pigs, swine and cattle and support further development of these VLP as a vaccine candidate for protection against FMDV.

Development and validation of an ELISA using a protein encoded by ORF2 antigenic domain of porcine circovirus type 2.

BACKGROUND: The capsid protein (ORF2) is a major structural protein of porcine circovirus type 2 (PCV2). A simple and reliable diagnostic method based on ORF2 protein immunoreactivity would serve as a valuable diagnostic method for detecting serum antibodies to PCV2 and monitoring PCV infection. Here, we reported an indirect enzyme-linked immunosorbent assay (I-ELISA) by using an antigenic domain (113-147AA) of ORF2-encoded antigen, expressed in E. coli, for diagnosis of PCV infection. RESULTS: The ELISA was performed on 288 serum samples collected from different porcine herds and compared with an indirect immunofluorescent assay (IFA). In total, 262 of 288 samples were positive as indicated by both I-ELISA and IFA. The specificity and sensitivity of I-ELISA were 87.7% and 93.57%. CONCLUSIONS: This ELISA is suitable for detection and discrimination of PCV2 infection in both SPF and farm antisera.

An ELISA based on a truncated soluble ORF2 protein for the detection of PCV2 antibodies in domestic pigs.

Postweaning multisystemic 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.

[Eukaryonization of T7 RNA polymerase prokaryotic expression system and development of its couple expression system].

To make transcription of the target gene be driven by T7 RNA polymerase (T7 RNAP) in the eukaryotic cells, and the transcripts be CAP-independent translated. Firstly, the T7 RNAP was introduced into eukaryotic cells by two methods: (1) the BHK-21 cells were contransfected by the plasmid expressing T7 RNAP and pIERS-EGFP-ET vector; (2) by transfection of the cell line stably expressing T7 RNAP. The internal ribosome entry site (IRES) element from FMDV was cloned into the downstream of the T7 promoter sequence of the prokaryotic expressing vector pET-40a-c (+), resulted in the plasmid would express the transcripts carrying the IERS element at its 5' end. The enhanced green fluorescent protein (EGFP) gene was cloned into the downstream of the IERS element, resulted in plasmid pIERS-EGFP-ET. Then, the two kinds of cells expressing T7 RANP were transfected by pIERS-EGFP-ET. The green fluorescence in the transfected cells was observed under a fluorescence microscope equipped with a video documentation system. And the expressional efficiency was analyzed with flow cytometry (FCM). The results show that the IRES element from FMDV has the role of initiating CAP-independent translation, and lay foundation for researching function of the element and interrelated proteins. It would be potential for expressing target gene by the T7 RNAP couple expression system.

[Construction and sequencing of full-length cDNA clone of swine vesicular disease virus strain HK'1/70].

By RACE, 2 overlapping cDNA fragments (3'PCR and 5'PCR fragments) covering the full genome of swine vesicular disease virus strain HK'1/70 were amplified from total RNA extracted from experimentally infected suckling mice. These fragments were cloned into pGEM-T Easy vector, respectively. 5'PCR fragment was digested by enzymes of Aat II and BssH II, and the Aat II-BssH II-digested 5'PCR fragment was obtained and cloned into the recombinant pGEM-T Easy vector containing 3'PCR fragment,the recombinant plasmid encoding full-length cDNA of SVDV HK'I/70 strain was then obtained and sequenced. The results showed that the complete genome of HK'1/70 was 7401 nucleotides (nts) long (excluding the poly (A) tract) which encodes a single polyprotein of 2185 amino acids, a 5'u ntranslating region (UTR) of 743 nts, a 3'UTR of 102 nts and a poly (A) tail at least 74 adenines. T' promoter was added at the 5'e nd of the full-length cDNA and an additional Pspl406I restriction site was added at the 3'e nd of poly (A) tail. The nucleotide and amino acid sequences were compared and phylogenetic analysis was used to examine the evolutionary relationships. The results showed that HK'1 /70 belonged to the second antigenic group. SVD virus was antigenically closely related to Coxsackie B5 virus, and located on the branches of CB5 evolutionary tree. Successful construction of full-length cDNA clone of SVDV HK'1/70 strain lays foundation for rescuing SVDV effectively and enables further research of SVDV on molecular level.

Protective immune responses in guinea pigs and swine induced by a suicidal DNA vaccine of the capsid gene of swine vesicular disease virus.

A suicidal DNA vaccine based on a Semliki Forest virus (SFV) replicon was evaluated for the development of a vaccine against swine vesicular disease virus (SVDV). The 1BCD gene of SVDV was cloned and inserted into pSCA1, an SFV DNA-based replicon vector. The resultant plasmid, pSCA/1BCD, was transfected into BHK-21 cells and the antigenicity of the expressed protein was confirmed using an indirect immunofluorescence assay. Immunogenicity was studied in guinea pigs and swine. Animals were injected intramuscularly three times with pSCA/1BCD at regular intervals. Anti-SVDV antibodies were detected by ELISA, the lymphocyte proliferation response was tested by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide method and neutralizing antibodies were measured by microneutralization tests. The data showed that SVDV-specific antibodies, neutralizing antibodies and lymphocyte proliferation were induced in both guinea pigs and swine. Furthermore, after three successive vaccinations with pSCA/1BCD, half of the pigs were protected against challenge with SVDV. These results should encourage further work towards the development of a DNA vaccine against SVDV.