RESUMEN
Objective To analyze the protein expression profile of HeLa cells transfected with pORF5 gene of Chlamydia trachomatis. Methods A lentiviral expression vector containing pORF5 gene was constructed. The lentiviral expression vector and helper plasmids were co-transfected into 293T cells to construct the recombinant lentivirus, which was used to infect HeLa cells. HeLa cells transfected with pORF5 gene and control HeLa cells were sorted out by flow cytometry. The isobaric tags for relative and absolute quantitation ( iTRAQ) approach combined with nano-liquid chromatography-tandem mass spec-trometry ( NanoLC-MS/MS) analysis was performed to understand protein expression profiles and to iden-tify and quantify the differentially expressed proteins in the pORF5-transfected HeLa cells ( pORF5-Hela) and the control HeLa cells. Quantitative real-time PCR ( qRT-PCR ) and Western blot analysis were performed to detect the expression of some proteins at mRNA and protein levels, respectively. Results HeLa cell line stably transfected with pORF5 gene and control HeLa cell line were constructed successful-ly. Totally 314 proteins were differentially expressed between the pORF5-HeLa and control HeLa cells, 159 of which showed increased expression and the other 155 showed decreased expression in pORF5-HeLa cells. The differentially expressed proteins were involved in many processes, such as metabolic process, immune response, biological adhesion and so on. Results of qRT-PCR showed that the expression of HIST1H1C(histone H1. 2C), HBA1(hemoglobin subunit alpha), PARK7(parkinson disease protein 7), HMGB1(high mobility group protein B1) and HMGB2 at mRNA level in pORF5-HeLa cells were up-regulated, while the expression of CLIC1 ( chloride intracellular channel protein 1 ) , KRT7 ( typeⅡ cy-toskeletal 7), SFN(14-3-3 protein sigma) and CDKN2A(cyclin-dependent kinase inhibitor 2A) were down-regulated. Western blot analysis confirmed the enhanced expression of HMGB1 and PRAK7 at pro-tein level. The results of qRT-PCR and Western blot analysis were consistent with proteomic data. Con-clusion Expression profiles for differentially expressed proteins between pORF5-HeLa and control HeLa cells were established successfully. The differentially expressed proteins regulated by pORF5 gene were found to be related to cell metabolism, proliferation, adhesion and so on, suggesting that pORF5 might promote the growth and proliferation of Ct by regulating protein expression and biological behavior of host cells.
RESUMEN
Objective:To investigate the immunogenicity of pORF5 plasmid protein,and further to screen and identify its im-munodominant domian.Methods: 10 different fragments of pORF5 gene including full length were amplified from the DNA of Chlamydia trachomatis serovar D by PCR and cloned into appropriate site of pGEX-6p vector to construct recombinant vectors after digested with BamHⅠand NotⅠrestriction endonucleases.After identification by PCR and sequencing,the recombinant plasmids were transformed into XL1 Blue E.coli to express the GST fusion proteins.ELISA and Western blot were carried out to identify the immunogenicity and immunoreaction of pORF5 plasmid protein.10 different fragments were reacted with sera from patients urogenitally infected with Chlamydia trachomatis, mouse polyclonal antibodies and mouse monoclonal antibodies of pORF5 plasmid protein with ELISA method.Results: pORF5 plasmid protein displayed strong immunogenicity and could induce a strong antibody response in human.The reactivity of human antibodies almost completely disappeared,when the native structure of pORF5 plasmid protein was de-stroyed.F6 that only lacked the N-terminal 66 amino acids was recognized by antibodies in ELISA as strongly as the whole pORF5 plasmid protein was.However,no other fragments were significantly recognized although there was a minimal reactivity of F2 and F3 with antibodies.Conclusion:pORF5 plasmid protein was an immunodominant antigen containing conformation-dependent epitope,and the C-terminal three quarters of pORF5 amino acid sequence was required for maintaining its immune dominance and conformation.The significance of the above findings lay a foundation for the further study on pORF5 protein function and vaccine development.