Abstract:

Objective
To study the interaction between D29 and macrophages and observe the titer variation of D29 both inside and outside the Mycobacterium tuberculosis(MTB) after phagocytised by macrophages and provide references for study on the mechanism and clinic therapy dose for treating tuberculosis. Methods The macrophages cultured in vitro were cracked at different time after D29 was mixed to estimate the titers of D29,at the same time,the supernatant fluid was collected after coincubated for 12 h to detect the levels of NO and IL-12 by enzyme-linked immunosorbent assay(ELISA);the titers of D29 were calculated both inside and outside the MTB by fluorescence quantitative PCR at different time after coincubated with macrophages which had phagocytised MTB.
Results There were about 2.5×104PFU of D29 phagocytised by macrophages after coincubated with 1×108PFU for 20 min,many of them were inactive after 180 min,there were hardly active D29 at 190 min;the supernatant IL-12 and NO levels  had no significant differences between D29 group and blank control group(P>0.05),but they  were significantly lower than those in LPS positive group (P<0.05);D29 could enter MTB phagocytised by macrophages after coincubated for 30 min;when coincubated for 40 and 50 min,the titers of D29 were increased both inside and outside the MTB,then were decreased;they began to decrease largely at 190 and 210 min,while at 48 h D29 couldn’t be detected.Conclusion D29 might be inactive after phagocytised by macrophages,and D29 could not influence the immunologic function of macrophages;D29 can enter MTB phagocytised by macrophages,at first,with the prolongation of the time,the number of D29 in MTB is increased,afterwards,D29 begins to decrease and disappears in the end.

Key words: mycobacteriophage;macrophages;Mycobacterium tuberculosis