Ka. Mcdonough et al., Intracellular passage within macrophages affects the trafficking of virulent tubercle bacilli upon reinfection of other macrophages in a serum-dependent manner, TUBERC LUNG, 80(6), 2000, pp. 259-271
Objective: The objective was to determine whether prior passage within macr
ophages affects the behavior of Mycobacterium tuberculosis (Mtb) upon re-en
try into other macrophages.
Design: Transmission electron microscopy was used to monitor fusion of bact
erial phagosomes with late endosomal/lysosomal compartments using thoria as
a fluid phase marker. Two-dimensional polyacrylamide gel electrophoresis w
as used to study bacterial protein expression within macrophages.
Results: H37Rv and BCG expressed novel proteins within macrophages. H37Rv a
lso underwent less fusion after intracellular (IC) (24.2 +/- 7.7%) than ext
racellular (XC) (67.4 +/- 5.5%) passage when the bacteria entered new macro
phages in small clusters. These effects were inhibited by serum, and were n
ot observed with H37Ra or BCG bacteria (78.9 +/- 1.6% fused for all conditi
ons). In addition, vacuoles which contained single bacilli were less likely
to acquire markers (26.9 +/- 2.6%) than those that contained multiple baci
lli (77.3 +/- 2.8%).
Conclusion: These results indicate that phagolysosomal fusion patterns can
be modulated by a variety of factors and that virulent Mtb bacteria may exp
ress proteins within macrophages that alter their interaction with these ho
st cells. (C) 2001 Harcourt Publishers Ltd.