RESUMO
Objective To introduce real-time polymerase chain reaction (real-time PCR) into the initial sample screening, to improve the effectiveness of traditional trace sample extraction method.Methods Serial diluted 9947A was quantified using a Rotor-Gene Q real-time RT-PCR, and the genotype was determined with AmpF?STRTMIdentifilerTMPlus PCR kit.Thus a quantitative threshold model was built to obtain complete STR typing from the trace samples.In addition, 903 trace samples were used to verify the reliability.Results When the samples quality concentration was＞0.03 ng/μL, the effective STR typing could be directly obtained;when the concentration was＞0.01 and≤0.03 ng/μL, the effective STR typing could be directly obtained by optimizing the PCR thermal cycle parameters (30 cycles);and when the concentration was≤0.01 ng/μL, no effective map could be obtained even if PCR was optimized.Conclusion The real-time PCR quantitative threshold model is effective for the screening of trace samples.