Establishment of real-time PCR method on detecting costimulatory molecule B7-H4 expression

Objective To establish a real-time polymerase chain reaction (PCR) method to detect costimulatory molecule B7-H4 gene expression. Methods The mRNA levels of costimulatory molecule B7-H4 and the reference gene GAPDH were detected by using real-time PCR using TaqMan technology. The primers and TaqMan probes of B7-H4 and GAPDH were designed. The B7-H4 and internal reference gene GAPDH fragments in pure form from classical PCR amplification were cloned into pMD19-T vector, and recombinant plasmids were used as the standard substances of B7-H4 and GAPDH quantitative detection.Standard curves were established using a serial dilution of quantified plasmids to measure B7-H4 and GAPDH. The reaction systems were optimized, and the sensitivity, specificity and reproducibility were evaluated. Results The amplification products were confirmed as the specific fragments of B7-H4 and GAPDH by DNA sequencing instrument. For B7-H4, the sensitivity was 527 copies/ml. The linear range was from 5.27 × 102 to 5.27 × 107 copies/ml, the standard curve equation was Y = - 3. 1395X +41. 805, the correlation coeffecient was 0. 995, the interassay coefficient of variations was 2. 39% -3.59%, and the amplification efficiency was 108.2%; For GAPDH, the sensitivity was 386 copies/ml. The linear range was from 3. 86 × 102 to 3.86 × 107 copies/ml, the standard curve equation was Y = - 3. 2436X +41. 083, the correlation coeffecient was 0. 999, the interassay coefficient of variations was 2. 26% -3. 86%, and the amplification efficiency was 103.4%. Conclusion The real-time PCR system for quantifying costimulatory molecule B7-H4 mRNA levels has been established successfully with high specificity, sensitivity and good repeatability. Key words: B7-H4; Costimulatory molecule; Real-time PCR