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Association of mouse fibrinogen-like protein with murine hepatitis virus-induced prothrombinase activity
1Department of Pathology, University of Texas Medical School at Houston 77225, USA.
Abstract:
Previously, we demonstrated induction of a unique macrophage prothrombinase during infection of BALB/cJ mice by mouse hepatitis virus strain 3 (MHV-3). By immunologic screening, a clone representing this prothrombinase was isolated from a cDNA library and sequenced. The sequence identified this clone as representing part of a gene, musfiblp, that encodes a fibrinogen-like protein. Six additional clones were isolated, and one clone, p11-3-1, encompassed the entire coding region of musfiblp. Murine macrophages did not constitutively express musfiblp but, when infected with MHV-3, synthesized musfiblp-specific mRNA. musfiblp mRNA induction was earlier and significantly greater in BALB/cJ than A/J macrophages. Prothrombinase activity was demonstrated when musfiblp was expressed from p11-3-1 in RAW 264.7 cells. These data suggest that musfiblp encodes the MHV-induced prothrombinase.
Insights
Mouse hepatitis virus-3 (MHV-3) infection induces a unique macrophage prothrombinase. This study identified the musfiblp gene as encoding this prothrombinase, crucial for viral infection response.
Area of Science:
- Immunology
- Virology
- Molecular Biology
Background:
- Macrophage prothrombinase induction was previously observed during mouse hepatitis virus strain 3 (MHV-3) infection.
- The specific gene responsible for this induced prothrombinase remained unidentified.
Purpose of the Study:
- To identify and characterize the gene encoding the MHV-3-induced macrophage prothrombinase.
- To investigate the expression patterns of this gene in different mouse strains during MHV-3 infection.
Main Methods:
- Immunologic screening of a cDNA library to isolate prothrombinase-encoding clones.
- Sequencing of isolated clones to identify the gene.
- Analysis of musfiblp mRNA expression in murine macrophages after MHV-3 infection.
- Functional assay of prothrombinase activity upon expression of the identified gene.
Main Results:
- A clone representing part of the musfiblp gene, encoding a fibrinogen-like protein, was isolated and sequenced.
- Murine macrophages did not constitutively express musfiblp but synthesized musfiblp-specific mRNA upon MHV-3 infection.
- musfiblp mRNA induction was significantly higher and earlier in BALB/cJ than A/J macrophages.
- Expression of musfiblp from a clone (p11-3-1) conferred prothrombinase activity.
Conclusions:
- The musfiblp gene encodes the prothrombinase induced during MHV-3 infection.
- Differential expression of musfiblp in BALB/cJ and A/J macrophages suggests strain-specific responses to MHV-3.
- musfiblp plays a role in the host response to MHV-3 infection.