My
lab has two ongoing research projects. The first relates to the molecular
biology and replication of mouse hepatitis virus, the second to the molecular
and cellular bases for the pathogenesis of MHV induced disease. We have
recently identified two RNA sequences at the 3' end of the MHV genome which
specifically bind host proteins. We are investigating the hypothesis that binding
of
host cell proteins to the genome is an important step in MHV RNA replication.
Biochemical characterization of protein binding sites is being undertaken by
mutagenesis and structural studies of RNAs with protein binding activity. Synthetic
RNA replicons are utilized to study the role of protein binding in viral replication.
We have recently identified several of the proteins which interact with the
3' end of the RNA genome. One of these proteins is surprisingly the enzyme mitochondrial
aconitase. Mitochondrial aconitase is the mitochondrial counterpart to
a very well characterized RNA binding protein, cytoplasmic aconitase, better
known as the iron regulatory protein (IRP-1). We are studying the
structural basis of this interaction and its functional significance.
Interactions with MHV proteins, particularly MHV polymerase proteins are being
sought by genetic and biochemical methods.
A second project
relates to the mechanism by which MHV kills infected cells, and how this
may affect the pathogenesis of disease in both the fulminant hepatitis
and multiple sclerosis models. In fully susceptible strains of mice, MHV-3
produces a lethal fulminant hepatitis characterized by massive hepatocellular
necrosis. In contrast, resistant strains of mice survive the infection
little evidence of hepatic injury. We have recently observed that MHV-3
induces rapid cell suicide (apoptosis) in infected macrophages derived
from strain resistant A/J mice, while replicating rapidly and efficiently
in susceptible Balb/c derived macrophages. This rapid onset of apoptosis
is correlated with inhibition of MHV induced cell fusion and virus spread.
We have recently extended this observation to demonstrate the MHV infectioni
induces apoptosis in other types of cells as well. We are interested in
delineating the pathways and regulators of MHV induced apoptosis using
biochemical, pharmacologic, and genetic approaches as well as investigating
the role of the apoptotic response in the pathogenesis of MHV induced disease.
A third ongoing
project investigates the mechanism of induction of a host-encoded prothrombinase
during MHV infection. This enzyme is an important mediator of liver injury,
and the induction of prothrombinase activity is a major determinant in
the outcome of infection. We are currently investigating the transcriptional
and post-transcriptional mechanisms of up-regulation of this gene during
MHV infection. Additional projects available for study include investigations
into the structure and function of MHV non-virion proteins and the role
of the small viral envelope protein in replication.
Representative
Publications:
Liu,Q., Johnson, R.F., and Leibowitz, J.L.: Secondary structural elements
within the 3' untranslated region of mouse hepatitis virus strain JHM genomic
RNA. J. Virol., in press.
Nanda, S.K., and Leibowitz, J.L.: Mitochondrial aconitase binds to the
3'-untranslated region of the mouse hepatitis virus genome. J. Virol.
75:3352-3362, 2001.
Ninq, Q., Liu, M., Lai, M.M.C., Marsden, P.A., Cole, E., Tseng, J.,
Pereira, B., Belyavskyi, M., Leibowitz, J.L., Phillips, M.J., and Levy,
G.A.: The nucleocapsid protein of murine hepatitis virus type 3 induces
transcription of the novel fgl2 prothrombinase gene. J. Biol. Chem.
274:9930-9936, 1999.
Belyavskyi, M., Belyavskaya, E., Levy, G.A., and Leibowitz, J.L.: Coronavirus
MHV-3 induced apoptosis in macrophages. Virology 250:41-49, 1998.
Liu,Q., Yu, W., and Leibowitz, J.L.: A specific host cellular protein
binding element near the 3' end of mouse hepatitis virus genomic RNA. Virology
232:74-85, 1997.
Yu, W., and Leibowitz, J.L.: A conserved motif at the 3' end of mouse
hepatitis virus genomic RNA required for host protein binding and viral
RNA replications. Virology 214:128-138, 1995.
Yu, W., and Leibowitz, J.L.: Specific binding of host cellular proteins
to multiple sites within the 3' end of mouse hepatitis virus genomic RNA.
J. Virol. 69:2016-2023, 1995.
Parr, R.L., Fung, L.S., Reneker, S.J., Myers-Mason, N., Leibowitz, J.L.,
and Levy, G.A.: The association of mouse fibrinogen-like protein (musfiblp)
with murine hepatitis virus induced prothrombinase activity. J. Virol.
69:5033-5038, 1995.
My
lab has two ongoing research projects. The first relates to the molecular
biology and replication of mouse hepatitis virus, the second to the molecular
and cellular bases for the pathogenesis of MHV induced disease. We have
recently identified two RNA sequences at the 3' end of the MHV genome which
specifically bind host proteins. We are investigating the hypothesis that binding
o
f
host cell proteins to the genome is an important step in MHV RNA replication.
Biochemical characterization of protein binding sites is being undertaken by
mutagenesis and structural studies of RNAs with protein binding activity. Synthetic
RNA replicons are utilized to study the role of protein binding in viral replication.
We have recently identified several of the proteins which interact with the
3' end of the RNA genome. One of these proteins is surprisingly the enzyme mitochondrial
aconitase. Mitochondrial aconitase is the mitochondrial counterpart to
a very well characterized RNA binding protein, cytoplasmic aconitase, better
known as the iron regulatory protein (IRP-1). We are studying the
structural basis of this interaction and its functional significance.
Interactions with MHV proteins, particularly MHV polymerase proteins are being
sought by genetic and biochemical methods. 