Background: ASF was first reported in Kenya in 1910 in 1921. In China, ASF spread to 31 provinces including Henan and Jiangsu within six months after it was first reported on August 3, 2018. The epidemic almost affected the whole China, causing direct economic losses of tens of billions of yuan. Cause great loss to our pig industry. As ELISA is cheap and easy to operate, OIE regards it as the preferred serological method for ASF detection. P54 protein has good antigenicity and is an ideal antigen for detection. Objective: To identify a conservative site in the African swine fever virus (ASFV) p54 protein and perform a Cloth-enzyme-linked immunosorbent assay (ELISA) for detecting the ASFV antibody in order to reduce risks posed by using the live virus in diagnostic assays.Method: We used bioinformatics methods to predict the antigen epitope of the ASFV p54 protein in combination with the antigenic index and artificially synthesized the predicted antigen epitope peptides. Using ASFV-positive serum and specific monoclonal antibodies (mAbs), we performed indirect ELISA and blocking ELISA to verify the immunological properties of the predicted epitope polypeptide. Results: The results of our prediction revealed that the possible antigen epitope regions were A23–29, A36–45, A72–94, A114–120, A124–130, and A137–150. The indirect ELISA showed that the peptides A23–29, A36–45, A72–94, A114–120, and A137–150 have good antigenicity.Moreover, the A36–45 polypeptide can react specifically with the mAb secreted by hybridoma cells, and its binding site contains a minimum number of essential amino acids in the sequence 37DIQFINPY44. Conclusions Our study confirmed a conservative antigenic site in the ASFV p54 protein and its amino acid sequence. A competitive ELISA method for detecting ASFV antibodies was established based on recombinant p54 and matching mAb. Moreover, testing the protein sequence alignment verified that the method can theoretically detect antibodies produced by pigs affected by nearly all ASFVs worldwide.

We designed the specific primers and TaqMan probes targeting cytochrome b genes of mitochondrial DNA from bovine, goat and sheep. We used different fluorescents to label the probes. After optimization of reaction conditions, we set up a multiplex fluorescent real-time PCR method to detect bovine, goat and sheep derived materials, simultaneously. We finished the detection tests of 17 kinds of animal DNA and 200 DNA samples from different sources with the developed method and the National Standard GB/T 20190Y-2006 routine PCR method. The coincidence rate of these two methods was 100%. Without electrophoresis or restriction digestion, the developed method could reduce the test time to one third as routine PCR and identify three kinds of animal derived materials including bovine, goat and sheep in one reaction. The developed method was approximately 10 times more sensitive than routine PCR, and was applicable to identifications of bovine, goat and sheep derived materials in feed stuff, meat, milk, pelt and grease, etc. The study showed that the developed real-time PCR method is a rapid, sensitive and efficacious detection assay for bovine, goat and sheep derived materials in animal products.
Animal Feed ; analysis ; Animals ; Cattle ; Cytochromes b ; genetics ; DNA Primers ; DNA, Mitochondrial ; analysis ; genetics ; Food Contamination ; analysis ; Genes, Mitochondrial ; Goats ; Meat ; analysis ; Mitochondria, Muscle ; enzymology ; genetics ; Polymerase Chain Reaction ; methods ; Sheep

African swine fever virus(ASFV)I177L gene deletion vaccine is one of the key directions of African swine fever(ASF)live attenuated vaccine research and development.In order to effec-tively distinguish between the wild-type ASFV strain and the I177L gene-deleted strain,specific primers and probes were designed based on ASFV B646L and I177L genes,respectively.After screening and optimization,a duplex real-time PCR method was developed that can simultaneously detect these two genes.The results showed that ASFV B646L and I177L genes were detected spe-cifically and simultaneously by the method developed without cross-reactions with porcine circovir-us type 2,Seneca virus A,classical swine fever virus,foot-and-mouth disease virus,porcine respira-tory and reproductive syndrome virus.The detection limits of the duplex real-time PCR for recom-binant plasmids pUC57-B646L and pUC57-I177L were 1×103 copies/mL.The intra-and inter-as-say coefficients of variation were less than 4％,respectively.Detection of 122 pork and pork prod-ucts using the duplex real-time PCR developed and the real-time PCR recommended by WOAH showed that the coincidence rates of the two methods for B646L gene detection was 100％with two amplification curves appeared in the positive results of the established methods.The method established in this study can be used for the detection of ASFV I177L gene deletion strains,which provides technical support for ASF surveillance and epidemiological investigation.