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Physiology
and gene expression in Borrelia
burgdorferi
We are
investigating the physiology of B.
burgdorferi (the causative agent
of Lyme disease) with an emphasis on gene expression during
starvation-stress. Lyme disease is the most prevalent arthropod
vector-borne disease in North America. B.
burgdorferi cells shuttle
between their tick-vector and their mammalian hosts. The tick host
(Ixodes
scapularis) takes only
three blood meals during its two-year
life cycle, yet the bacteria survive for extended periods in the tick
midgut between feedings. Additionally, the bacteria may enter nutrient
limited sites in the mammalian host, such as the cerebral spinal fluid.
We are interested in examining the regulation of the of gene expression
during starvation or nutrient limitation. Recent evidence from my lab
suggests that B. burgdorferi
cells: 1) respond to serum starvation with a temporally controlled
program of changes in protein expression; and 2) regulate their
responses to starvation by the stringent response, controlled by SpoT
(encoded by spoT)
and by alternative sigma factors such as RpoS or  (encoded by rpoS).
This work is being
carried out in collaboration with Dr. Thomas Mather (URI), Dr. Ira
Schwartz (NY Medical College), and Dr. Richard Marconi (Virginia
Commonwealth University). Our previous studies of B.
burgdorferi have examined heat
shock or stress-proteins and their roles in disease and as chaperone
proteins.
Borrelia
burgdorferi - micrograph (strain
B31 in BSK
media) after staining with fluorochrome dye, acridine orange.
Magnification 500x
- Girouard,
L.A., S. Jindal, D.C. Laux, and D.R. Nelson. 1993. Immune
recognition of human Hsp60 by Lyme disease patient sera. Microbial
Path. 14:287-297.
- Scorpio,
A., A. Laquerre, P.
Johnson, D.C. Laux, and D.R. Nelson. 1994. Subcellular localization and
chaperone functions of Hsp60 and Hsp70 in Borrelia
burgdorferi. J. Bacteriol.
176:6449-6456.
- Ewing,
C.A. Scorpio, D.R. Nelson,
and T. Mather. 1994. Isolation of Borrelia
burgdorferi from saliva of the
tick vector, Ixodes scapularis.
J. Clin. Microbiol. 32:755-758.
- Alban,
P.S., P.W. Johnson, and
D.R. Nelson. 2000. Serum starvation-induced changes in protein
synthesis and morphology of Borrelia
burgdorferi. Microbiology
146:119-127
- Nelson,
D.R., Rooney, S., N.
Miller, and T.N. Mather. 2000. Complement-mediated killing of Borrelia
burgdorferi in deer sera. J.
Parasitol. 86:1232-1238.
- Roberts,
D.M., M.J. Caimano, J.D.
Radolf, D.R. Nelson, and R.T. Marconi. 2002. Influence of environmental
conditions on the expression and cellular partitioning of members of
the Bdr protein family in the Lyme disease spirochetes. Infect. Immun.
70:7033-7041
- Concepcion,
M.B. and D.R. Nelson.
2003. Expression of spoT in Borrelia
burgdorferi during serum
starvation. J.
Bacteriol. 185:444-452
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