ABSTRACT
This study was aimed to establish ELISA for recombinant bovine IFN-gamma (BovIFN-gamma) detection and provide a new method for diagnosis of pathogenic infection. The total RNA was isolated from peripheral blood leucocytes cultured with PHA mitogen stimulation. Then bovine IFN-gamma (BovIFN-gamma) gene cDNA was amplified by RT-PCR and cloned into pET28a to obtain the expression plasmid designated as pETBovIFN-gamma. The pETBovlFN-gamma was further transformed into competent E. coli BL21 cells and a 18kD His-tagged protein as expected was expressed after IPTG induction. By using purified recombinant BovIFN-gamma as antigen and lymphocyte-hybridoma technique, four hybridoma cell lines which stably secreted monoclonal antibodies against rBovIFN-gamma were generated, designated as A7, A10, G6, and G10. The immunoglobin subset was identified as IgG1 . Western-blotting analysis and ELISA demonstrated that the monoclonal antibodies secreted by all the four hybridoma cell lines could react specifically to the recombinant BovIFN-gamma, but not irrelative proteins such as Ag85B, ESAT-6-CFP-10 and GM-CSF, suggesting that the four hybridoma cell lines were rBovIFN-gamma specific monoclonal antibodies. A sandwich ELISA was established by using A10 secreted monoclonal antibody and rabbit polyclonal antibodies against BovIFN-gamma, HRP labeled goat anti-rabbit IgG. The results indicated that the sensitivity was 2ng/mL. This sandwich ELISA to detect BovIFN-gamma paved the way to develop a sensitive method for specific infection detection such as bovine tuberculosis diagnosis.
Subject(s)
Animals , Cattle , Female , Mice , Rabbits , Animals, Newborn , Antibodies, Monoclonal , Allergy and Immunology , Antibody Specificity , Allergy and Immunology , Blotting, Western , Cells, Cultured , DNA, Complementary , Genetics , Enzyme-Linked Immunosorbent Assay , Methods , Hybridomas , Interferon-gamma , Genetics , Allergy and Immunology , Metabolism , Mice, Inbred BALB C , Plasmids , Genetics , Recombinant Proteins , Allergy and Immunology , Metabolism , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Taking the genome DNA of Infectious Bovine Rhinotracheitis Virus (IBRV) as the template, the gG gene was amplified with PCR and cloned into the T cloning vector pMD18-T. After being identified by restriction digestion and DNA sequencing, the insert was subcloned into the expression vector pGEX-KG. Sodium docecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot assay showed that this gene was expressed as both soluble form and inclusion body by the transformed E. coli BL21 strain (DE3). The fusion protein was purified and used as the coating antigen to develop the indirect Enzyme-Linked Immunosorbent Assay (ELISA). Comparison between this gG-ELISA and commercial IBRV gB-ELISA Kit (IDEXX) was made in the detection of 380 cow serum samples. The results demonstrated an agreement of 92%. By using this novel gG-ELISA, 1248 cow serum samples were tested and the average positive rate of IBRV antibodies for imported cows is 21.7%, while the positive rate ranged greatly from 0.0%-41.5% for Hubei local Chinese Black and White Dairy Cows.