Establishment and application of a new immune-comb assay for detection of serum antibody against simian immunodeficiency virus / 中国实验动物学报

Objective SIV30 protein of simian immunodeficiency virus(SIV)was prepared by genetic engineering technique as an antigen diagnostic reagent, to establish an immune comb method for the specific detection of anti SIV IgG in monkey serum. Methods Recombinant expression plasmid of SIV SIV30 gene was constructed by prokaryotic expression vector pGEX-4T-1, and expressed in the competent BL21 cells. The recombinant protein was purified as a diagnostic antigen, and a standardized procedure for the detection of immune comb was established and applied for clinical detection. Results The optimum coating amount of antigen was 0.02 mg/mL. The prepared IC was able to specifically detect the positive serum of SIV. There was no cross reaction between the sera of other viruses. It showed a high specificity of the detection method. Sensitivity analysis showed that the SIV30 protein was able to detect 1:400 times diluted SIV positive sera. The result of stability and repeatability test(the same sample was repeated 3 times) showed that the coefficient of variation(CV)was less than 10%. The serum samples of 10 suspicious monkeys were detected by this method, showing a consistent rate of comb method and ELISA test result of 100%, Kappa =1.000. Conclusions SIV30 protein is expressed in prokaryotic cells. The immune comb is prepared,and is successfullyl applied in clinical examination. It shows that the method has a high sensitivity, strong specificity, good reproducibility and practicability.

Isolation and identification of porcine epidemic diarrhea virus strain LN-2015-1 and its S gene mutation analysis / 中国兽医学报

In order to understand the porcine epidemic diarrhea virus (PEDV) origin and variant characteristics in Liaoning province,diagnosed by PCR,separated by Vero cell,and identified by cell pathological observation,RT-PCR and S gene sequence analysis,1 PEDV strains (LN-2015-1) was successfully isolated from a pig farm of Liaoning province.Analysis of S gene sequence showed that compared withCV777 strain,there were the longest 9 bp insertion,6 bp deletion and 13 bp continuous mutation in addition to point mutation.There also were the longest 3 AA insert,2 AA deletion,and 3 AA or more continuous mutation.The epitope analysis showed that there were 16AA mutations in the 5 epitope regions.Homology analysis show that it had the highest sequence similarity of 99.2％ with HB-HA2015 strain,higher sequence similarity of 98.5％-98.8％ with the domestic and foreign representative strains isolated since 2010,and lower sequence similarity of 93.2％-95.6％ with the traditional strain isolated before 2010;the phylogenetic analysis showed that LN-2015-1 was clustered into the same group with home and abroad variation strain in recent years,and formed a small subgroup with HB-HA2015 at the same time.The evolutionary distance was far from the traditional strains.

A recombinant polypeptide from velvet antler of Cervus nippon Temminck exhibits similar immunomodulatory effects as its natural counterpart.

CONTEXT: Velvet antler (VA) is recognized as one of the most important Chinese traditional medical herbs. To date, the immunoactivity of the single component of VA is rarely studied though its compound extracts have been well analyzed. OBJECTIVE: The current study was designed to evaluate the immunomodulatory effects of a recombinant polypeptide (rVAP32) based on the VA of the sika deer by comparison with its natural counterpart (nVAP32). MATERIALS AND METHODS: Splenocytes proliferation and NK-cell cytotoxicity assay was evaluated by the WST-8 colorimetric method. CD4+/CD8+ cell subpopulations regulation was screened by the flowcytometry method and the Th1 or Th2-related cytokine production was measured by ELISA. RESULTS: In vitro tests showed that both rVAP32 and nVAP32 could significantly stimulate splenocytes proliferation and enhance the NK-cell cytotoxicity and CD4+/CD8+ cell subpopulations when compared with the irrelevant peptide and blank control groups. Also, they demonstrated a significant capacity in up- and down-regulating the expression of Th1- and Th2-related cytokines, respectively. There is no statistically significant difference found between the rVAP32 tested group and nVAP32 control group. DISCUSSION AND CONCLUSION: The results obtained herein indicate that rVAP32 has the similar immunomodulatory effects on the immune system of mice as its counterpart nVAP32 in vitro. The further test in vivo is qualified and rVAP32 is promised for developing a new biopharmaceutical product as a substitute for nVAP32.

Design and evaluation of a recombinant multi-epitope-based ELISA for the serological surveillance of HEV infection in northern China.

In this study, seven recombinant epitope peptides from within the ORF2 protein of the local genotype 4 swine hepatitis E virus (HEV) DQ strain were designed and analyzed. Then, a new multi-epitope-based ELISA was established. In comparison with a commercial kit, this test exhibited good specificity and sensitivity for anti-HEV genotype 4. Subsequently, this test was applied for analyzing serum samples from either swine herds or human populations in northern China. The overall seroprevalence rate of anti-HEV IgG reached up to 40.4% for swine and 8.1% for humans. A statistical difference was observed for humans in rural and urban areas, with a higher prevalence for people living in rural than urban areas. Moreover, sequencing confirmed that all RNA-positive samples belonged to genotype 4.

High-level prokaryotic expression of envelope exterior of membrane protein of porcine epidemic diarrhea virus.

The truncated fragment M' gene, encoding the exterior of the viral envelope protein of PEDV, was subcloned into prokaryotic expression vector pGEX-6p-1. The recombinant plasmid pGEX-6p-M' was constructed and transformed into E. coli BL21(DE3)pLysS for expression. SDS-PAGE analysis showed recombinant truncated M' protein was highly expressed by pGEX-6p-M' and the product fusion protein GST-M' reached 45% in the total bacteria proteins with the analysis of software AlphaImager2200. The preliminary purified recombinant protein was evaluated for its antigenicity and reactivity through Western blotting and indirect enzyme-linked immunosorbent assay (ELISA) with monoclonal antibody against M protein of PEDV and porcine polyclonal anti-PEDV antiserum as the primary antibody. The results indicated the recombinant truncated M' protein should be candidate as a feasible recombinant diagnostic reagent.