Development of an indirect ELISA against African swine fever virus using two recombinant antigens, partial p22 and p30.

African swine fever (ASF) is a highly fatal viral disease affecting pigs. It is caused by the ASF virus (ASFV), and causes serious economic losses to the swine industry worldwide, including in Korea. Commercially available enzyme-linked immunosorbent assay (ELISA) kits for detecting anti-ASFV antibodies are used for the diagnosis and surveillance of ASF. In this study, an ELISA was developed to detect anti-ASFV antibodies using two recombinant proteins, p22 and p30, from genotype II ASFV. Recombinant transmembrane domain-deleted p22 (p22∆TM) and p30 were expressed in E.coli vector system pET32a and mixed for use as antigens in indirect ELISA. The p22∆TM/p30-based indirect ELISA was validated using 31 sera from genotype I ASFV-infected pigs and 1133 sera from uninfected pigs. Area under the curve of this test was 0.999 [95 % concentration interval 0.992-1.000], and sensitivity and specificity were 93.5 % and 99.8 %, respectively. The between run coefficient of variation for internal quality control serum was 6.61 %. In the seroconversion analysis, the p22∆TM/p30-based indirect ELISA showed equal or better ability to detect antibodies in pigs experimentally challenged with ASFV p72 genotypes I and II (p < 0.05). In conclusion, the p22∆TM/p30-based indirect ELISA is a reliable diagnostic method for detecting anti-ASFV antibodies.