Expression of porcine reproductive and respiratory syndrome virus (PRRSV) ORF7 gene and monoclonal antibody production

Abstract Porcine reproductive and respiratory syndrome virus (PRRSV) is the etiological agent of PRRS charac-terized by reproductive losses in sows and respiratory disorders in piglets. The PRRSV is a small envel-oped virus containing a positive-sense, single-stranded RNA genome and divided into two genotype, type 1 (European) and type 2 (North American), respectively, by nucleotide identity. In this study, ORF7 gene of the type 1 and type 2 PRRSV was cloned and expressed in Baculovirus expression system. Also, monoclonal antibodies (MAbs) against ORF7 were produced and characterized. The ex-pressed ORF7 proteins in the recombinant virus were confirmed by indirect fluorescence antibody (IFA) test using His6 and PRRSV-specific antiserum. A total of eight MAbs were produced and characterized. One (3G12) MAb was type 1 PRRSV ORF7-specific and two (6B10 and 16H8) were type 2 PRRSV ORF7-specific. Other five (1A1, 2A4, 4B4, 12C4 and 13F11) MAbs reacted with both type 1 and type 2 PRRSV. Some PRRSV ORF7-specific MAbs recognized the porcine tissues infected with PRRSV by IFA or immunohistochemistry (IHC) assay. From this experiment, it was confirmed that MAbs produced in this study were PRRSV ORF7-specific and could be used as reliable reagents for type 1/type 2 PRRSV detection.