Abstract: Objective To study the clinical value of Ag85B mRNA of M.tuberculosis in the sputums as a marker of monitoring the response of patients with pulmonary tuberculosis to chemotherapy.Method The sputums were collected from 15 smear-positive,primary treated patients with pulmonary tuberculosis at 2,4,7,14,30,60 days after receiving a standard short-course chemotherapic regimen,measured Ag85B mRNA of M.tuberculosis using quantitative reverse-transcribed polymerase chain reaction assay.The Results were compared with that using culture method.Results The level of Ag85B mRNA declined rapidly at 2 days after initiation of therapy,which was consistent with viable M.tuberculosis colony counts.Of 15 patients,11,12,and 14 had no detectable mRNA at 7,14,and 30 days after treatment,respectively.None of sputa had detectable mRNA at 60 days after treatment.Conclusion The rapid disappearance of M.tuberculosis Ag85B mRNA from sputum suggests that it might be a good indicator of microbial viability and a useful marker for rapid evaluation of response to chemotherapy.

Key words: Mycobacterium tuberculosis, Pulmonary tuberculosis, mRNA, RT?PCR, Response to chemotherapy