Preparation and Identification of Specific Monoclonal Antibody against Porcine Circovirus Type 2

BALB/c mice were immunized using synthetic tandem polypeptide of Cap protein epitope of porcine circovirus type 2 （PCV2） as the antigen. By using lym-phocyte hybridoma technique, a hybridoma cellline stably secreting monoclonal an-tibody against PCV2-rCap protein was successful y obtained and named as 670#. The ascites titer of the obtained monoclonal antibody was 1∶100 000. Western blot results showed that the monoclonal antibody could react with prokaryotical y ex-pressed PET32a-ORF2 recombinant protein, eukaryotical y expressed ORF1-ORF2 tandem protein and PCV2 whole virus celllysate. Indirect EILSA demonstrated that the monoclonal antibody could bind with ORF1-ORF2 tandem protein. Indirect im-munofluorescence assay （IFA） indicated that the monoclonal antibody could identify native PCV2 virus. The preparation of this monoclonal antibody provided technical tools for epitope analysis and molecular diagnosis of PCV2 virus.

An Indirect ELISA of Classical Swine Fever Virus Based on Quadruple Antigenic Epitope Peptide Expressed in E.coli

In this study,a synthesized quadruple antigenic epitope gene region of the classical swine fever virus (CSFV)E2 glycoprotein was expressed in E.coli to a obtain target protein.This target protein was used as a coating antigen to establish an indirect ELISA for specifically detecting anti-CSFV antibodies in serum samples from pigs.The P/N cut-off value of this assay was 1.92 by receiver operating characteristic curve(ROC)analysis based on 30 negative sera and 80 positive samples.The test gave 97.5%sensitivity and 96.7%specificity compared with the indirect hemagglutination(IHA)test.The inter-assay and intra-assay coefficients of variation (CVs)for 16 sera were both≤6.8%.No cross-reactivity between the coating antigen and anti-bovine viral diarrhoea virus(BVDV)antibodies was observed.

Identification of the Epitopes of Monoclonal Antibodies against P74 of Helicoverpa armigera Nucleopolyhedrovirus

P74 is a per os infectivity factor of baculovirus.Here,we report the production of three monoclonal antibodies (mAbs),denoted as 20D9,20F9 and 21E1,raised against P74 of Helicoverpa armigera nucleopolyhedrovirus (HearNPV),and the identification of their recognition epitopes.The full-length P74,without the transmembrane domains at the C-terminus,was first divided into three segments (N,M and C,respectively),based on the proposed cleavage model for the protein,which were then expressed individually.Western blot analyses revealed specific cross-reactions with the N fragment,for both 20D9 and 21E1.Extensive truncation,followed by prokaryotic expression,of the P74 N fragment was then performed in order to screen for linear epitopes of P74.The recognition regions of 20D9 and 21E1 were revealed to be localized at R144-T153 and T199-C219,respectively.In addition,immunofluorescence microscopy indicated that 20D9 and 20F9 could recognize native P74 in HearNPV-infected cells.These findings will facilitate further investigations of the proteolytic processing of HearNPV P74,and of its involvement in virus-host interactions.

Epitope variation in the Newcastle disease virus HN gene under antibody immune selective pressure in cell culture

The influence of antibody immune selective pressure on Newcastle disease virus (NDV) HN and F gene mutations was studied in cell cultures.NDV field strain TZ060107 was inoculated into chicken embryo fibroblast cells and continuously passaged with (group A) or without (group B) anti-NDV monospecific serum.Each group contained three independent passage series.HN and F genes were amplified and sequenced for the 10th,20th,30th,40th and 50th generations of each serial passage,and compared with the original strain.The results demonstrated that increased HN gene mutations were observed in group A with the antibody than in group B without the antibody.The nonsynonymous (NS) to synonymous (S) mutations ratio was 6 for group A,significantly higher than 3.4 in group B.In group A with the antibody,there were five stable NS mutations in HN gene,three of which (related to aa#353,521 and 568) were related to known epitopes.There were two stable NS mutations in F gene in group A,but no stable NS mutations in group B.The NS/S ratios of F gene were less than 2.5 for both groups A and B.Our results suggested that the antibody strongly influenced HN gene mutations,while the F gene was less influenced by the same antibody.

Synthetic immunity to break down the bottleneck of cancer immunotherapy

As a result of recent breakthroughs in cancer immunotherapies, unprecedented and durable remission, and even cure, has been reported in some patients. Importantly, this progress has been achieved, not by the induction of immunity, but by the delivery of immunity in the form of engineered antibodies （cAbs） or effector T cells. However, these single-target technologies have failed to result in a therapeutic effect in some patients, and evidence suggests that further advances depend on an effective strategy for coping with cancer heterogeneity and dynamics. A synthetic immunity （SI） strategy is proposed to achieve this goal. The fundamental basis of SI involves the generation of a panel of cAbs and antibody-retargeted CTLs designed to destroy all cell lineages of a cancer with high specificity. This goal can be achieved only when the composition of the cAbs is determined using a systematic approach, i.e., selecting the antigens targeted by the cAbs based on an epitope-tree illustrating the clonal antigen architecture of the cancer. Integration of technologies that increase the epitope breadth, cAb affinity and T cell activity will further enhance the efficacy of SI. Using DNA vectors to express the eAbs will be a safe, effective and affordable solution.