modifications that are not present in leptospires cultivated in vitro
[21]. The DMC model also provides an appropriate biological
framework for phenotypic characterization of a wide range of
mutations. Because leptospires are separated from host tissues, the
DMC model enables one to distinguish between gene products
required for physiological adaptation and nutrient acquisition and
those that serve virulence-related functions, such as adherence,
immune evasion, and motility. Lastly, this model is also well suited
to the investigation of environmental sensing, signal transduction,
and the molecular pathways underlying differential gene expression
by pathogenic Leptospira spp. within mammals.
The DMC model has been used successfully with several wellcharacterized virulent L. interrogans reference strains, including the
highly virulent sv. Manilae st. L495, the sv. Copenhageni
st. Fiocruz L1-130, and numerous transposon mutant strains.
The Fiocruz L1-130 and L495 strains grow at similar rates within
DMCs (Fig. 1) and yield comparable numbers of host-adapted
organisms. However, saprophytic L. biflexa sv. Patoc st. Patoc1
and pathogenic L. borgpetersenii sv. Hardjo sts. HB203 and
JB197 grew poorly or not at all within DMCs.
Fig. 1 L. interrogans serovar Copenhageni strain Fiocruz L1-130 and serovar Manilae strain L495 display
similar growth rates in DMCs. Growth of Fiocruz L1-130 (Cop) and L495 (Man) strains was compared in DMCs
and in vitro in EMJH at 37
C (IVC37). Both DMCs and IVC37 cultures were started at a density of
10
4 leptospires per ml in 10 ml total volume. One animal per day for each strain was euthanized beginning
either day 5 (Man) or day 7 (Cop). The content of each DMC was collected and counted in triplicate by darkfield microscopy using a Petroff-Hausser counting chamber. For IVC37, triplicate cultures of each strain were
counted once a day starting on day 5 postinoculation until days 11 (Man) or 12 (Cop)
Cultivation of Leptospira interrogans within DMCs
231
[21]. The DMC model also provides an appropriate biological
framework for phenotypic characterization of a wide range of
mutations. Because leptospires are separated from host tissues, the
DMC model enables one to distinguish between gene products
required for physiological adaptation and nutrient acquisition and
those that serve virulence-related functions, such as adherence,
immune evasion, and motility. Lastly, this model is also well suited
to the investigation of environmental sensing, signal transduction,
and the molecular pathways underlying differential gene expression
by pathogenic Leptospira spp. within mammals.
The DMC model has been used successfully with several wellcharacterized virulent L. interrogans reference strains, including the
highly virulent sv. Manilae st. L495, the sv. Copenhageni
st. Fiocruz L1-130, and numerous transposon mutant strains.
The Fiocruz L1-130 and L495 strains grow at similar rates within
DMCs (Fig. 1) and yield comparable numbers of host-adapted
organisms. However, saprophytic L. biflexa sv. Patoc st. Patoc1
and pathogenic L. borgpetersenii sv. Hardjo sts. HB203 and
JB197 grew poorly or not at all within DMCs.
Fig. 1 L. interrogans serovar Copenhageni strain Fiocruz L1-130 and serovar Manilae strain L495 display
similar growth rates in DMCs. Growth of Fiocruz L1-130 (Cop) and L495 (Man) strains was compared in DMCs
and in vitro in EMJH at 37
C (IVC37). Both DMCs and IVC37 cultures were started at a density of
10
4 leptospires per ml in 10 ml total volume. One animal per day for each strain was euthanized beginning
either day 5 (Man) or day 7 (Cop). The content of each DMC was collected and counted in triplicate by darkfield microscopy using a Petroff-Hausser counting chamber. For IVC37, triplicate cultures of each strain were
counted once a day starting on day 5 postinoculation until days 11 (Man) or 12 (Cop)
Cultivation of Leptospira interrogans within DMCs
231