Xiangtao Liu

Introduction: Orf virus (ORFV) is a prototype Parapoxvirus species in the Poxviridae family that causes serious zoonotic infectious disease. Goat skin fibroblast (GSF) cells are the major host targets of ORFV. Interleukin 8 (IL-8) and tumour necrosis factor (TNF)-α are known to play a vital role in immune response during viral infections. However, the manner of variation over time of their level of expression in GSF cells remains unclear.Material and Methods: In this study, quantitative enzyme-linked immunosorbent assay chips were used to detect changes in the levels of these cytokines expressed and secreted in GSF cells after ORFV infection.Results: Results showed that the expression of IL-8, TNF-α, and decorin was upregulated in the cell lysates, and that secreted decorin and IL-8 were significantly increased in cell supernatant.Conclusion: The results provided possible approaches to elucidation of how ORFV infection initiates host cell immune response.

This study reviews the FMDV receptor-binding domain, integrin receptors, and heparan sulfate receptors to provide references for studies regarding the mechanisms underlying FMDV infection.

Background: Orf virus (ORFV) causes orf (also known as contagious ecthyma or contagiouspapular dermatitis), a severe infectious skin disease in goats, sheep andother ruminants. Therefore, a rapid, highly specific and accurate method forthe diagnosis of ORFV infections is essential to ensure that the appropriatetreatments are administered and to reduce economic losses. Methods: A loop-mediated isothermal amplification (LAMP) assay based on theidentification of the F1L gene was developed for the specific detection ofORFV infections. The sensitivity and specificity of the LAMP assay wereevaluated, and the effectiveness of this method was compared with that ofreal-time PCR. Results: The sensitivity of this assay was determined to be 10 copies of a standardplasmid. Furthermore, no cross-reactivity was found with either capripoxvirus or FMDV. The LAMP and real-time PCR assays were both able to detectintracutaneous- and cohabitation-infection samples, with a concordance of97.83%. LAMP demonstrated a sensitivity of 89.13%. Conclusion: The LAMP assay is a highly efficient and practical method for detecting ORFVinfection. This LAMP method shows great potential for monitoring theprevalence of orf, and it could prove to be a powerful supplemental tool forcurrent diagnostic methods.

Background: In this study, we developed a SYBR Green-based real-time PCR assay for the detection of sheep pox virus using a plasmid construct carrying one of the highly conserved genes encoding the virion envelope protein (P32) as a template. Results: The method was demonstrated to be highly sensitive, allowing a precise SPV DNA quantitation over a range of nine orders of magnitude (from 10¹ to 10⁹ copies of standard DNA). Then, specimens from SPV suspected sheep were analyzed by conventional gel-based PCR, real-time PCR and sequence analysis. Conclusion: Comparison between these different techniques revealed that real-time PCR is more sensitive than conventional gel-based PCR, allowing detection low viral titers of SPV in infected sheep.

Background: Sheeppoxvirus (SPPV), goatpoxvirus (GTPV) and lumpy skin disease virus (LSDV) of cattle belong to the Capripoxvirus genus of the Poxviridae family and can cause significant economic losses in countries where they are endemic. Despite the considerable threat that these viruses pose to livestock production and global trade in sheep, goats, cattle and their products, convenient and effective serodiagnostic tools are not readily available. Toward this goal, two synthetic peptides corresponding to the major antigen P32 were synthesized. These synthetic peptides were then used as antigen to develop an ELISA method to detect anti-SPPV and GTPV antibodies. Results: The results indicated that the optimal concentration of coated recombinant antigen was 0.2 μg per well for a serum dilution of 1:10. The ELISA performed favorably when sera from sheep immunized experimentally were tested. Conclusion: This assay offers the prospect of synthetic peptide as antigens for indirect ELISA to detect SPPV and GTPV antibody in sheep and goat sera.

Background: Prompt detection of PRRSV in the field samples is important for effective PRRS control, thereby reducing the potentially serious economic damage which can result from an outbreak. In this study, a rapid SYBR-based, one step real-time RT-PCR quantitative reverse transcription PCR (qRT-PCR) has been developed for the detection of porcine reproductive and respiratory syndrome virus (PRRSV). Primers were designed based on the sequence of highly conservative region of PRRSV N gene. Results: The sensitivity of the real-time qRT-PCR assay was achieved through PRRSV ch-1a RNA for the generation of a standard curve. The detection limit of the assay was found to be 9.6 RNA copies per reaction mixture. This assay had excellent intra- and inter-assay reproducibility as in total 65 field samples were screened for the presence of PRRSV by conventional RT-PCR in parallel with qRT-PCR, and the detection rate increased from 60.0% to 76.9%. Moreover, the specificity result indicated that this assay could reliably differentiate PRRSV from the other swine viral diseases, such as classical swine fever virus (CSFV), swine vesicular disease virus (SVDV) and vesicular exanthema of swine virus (VESV). Conclusion: The real-time qRT-PCR assay described in this report allows the rapid, specific and sensitive laboratory detection of PRRSV in field samples.

A multiplex reverse transcription polymerase chain reaction (multiplex RT-PCR) was developed for the detection of porcine reproductive and respiratory syndrome virus (PRRSV). A set of three pairs of primer were designed based on the sequence of high conservative region of PRRSV. The diagnostic accuracy of the multiplex RT-PCR assay was evaluated using 25 field clinical samples, 10 reference strains and 6 true-negative samples. Simultaneously, the specificity and sensitivity of this method were evaluated. The result indicated that this assay could reliably differentiate between PRRSV and other swine viral disease, such as classical swine fever virus (CSFV), swine vesicular disease virus (SVDV) and vesicular exanthema of swine virus (VESV). Meanwhile, this assay was shown to be 10-fold more sensitive than the conventional single RT-PCR (conventional sRT-PCR) method. The results indicated that the multiplex RT-PCR developed in this study has high sensitivity, strong specificity and easy operation,it is not only suitable for diagnosis of samples of insignifiance content,but also it has important applied value in getting rid of animals with recessive virus and veterinary quarantine .The method may provide a new avenue to the rapid detection of this important pathogen in one reaction.