Reovirus replication protein μ2 influences cell tropism by promoting particle assembly within viral inclusions.

The double-stranded RNA virus mammalian reovirus displays broad cell, tissue, and host tropism. A critical checkpoint in the reovirus replication cycle resides within viral cytoplasmic inclusions, which are biosynthetic centers of genome multiplication and new-particle assembly. Replication of strain type 3 Dearing (T3) is arrested in Madin-Darby canine kidney (MDCK) cells at a step subsequent to inclusion development and prior to formation of genomic double-stranded RNA.

Molecular determinants of proteolytic disassembly of the reovirus outer capsid.

Following attachment and internalization, mammalian reoviruses undergo intracellular proteolytic disassembly followed by viral penetration into the cytoplasm. The initiating event in reovirus disassembly is the cathepsin-mediated proteolytic degradation of viral outer capsid protein σ3. A single tyrosine-to-histidine mutation at amino acid 354 (Y354H) of strain type 3 Dearing (T3D) σ3 enhances reovirus disassembly and confers resistance to protease inhibitors such as E64.

A single-amino-acid polymorphism in reovirus protein μ2 determines repression of interferon signaling and modulates myocarditis.

Myocarditis is indicated as the second leading cause of sudden death in young adults. Reovirus induces myocarditis in neonatal mice, providing a tractable model system for investigation of this important disease. Alpha/beta-interferon (IFN-α/β) treatment improves cardiac function and inhibits viral replication in patients with chronic myocarditis, and the host IFN-α/β response is a determinant of reovirus strain-specific differences in induction of myocarditis.

A post-entry step in the mammalian orthoreovirus replication cycle is a determinant of cell tropism.

Mammalian reoviruses replicate in a broad range of hosts, cells, and tissues. These viruses display strain-dependent variation in tropism for different types of cells in vivo and ex vivo. Early steps in the reovirus life cycle, attachment, entry, and disassembly, have been identified as pivotal points of virus-cell interaction that determine the fate of infection, either productive or abortive.

An improved reverse genetics system for mammalian orthoreoviruses.

Mammalian orthoreoviruses (reoviruses) are highly useful models for studies of double-stranded RNA virus replication and pathogenesis. We previously developed a strategy to recover prototype reovirus strain T3D from cloned cDNAs transfected into murine L929 fibroblast cells. Here, we report the development of a second-generation reovirus reverse genetics system featuring several major improvements: (1) the capacity to rescue prototype reovirus strain T1L, (2) reduction of required plasmids from 10 to 4, and (3) isolation of recombinant viruses following transfection of baby hamster kidney cells engineered to express bacteriophage T7 RNA polymerase.

Identification of functional domains in reovirus replication proteins muNS and mu2.

Mammalian reoviruses are nonenveloped particles containing a genome of 10 double-stranded RNA (dsRNA) gene segments. Reovirus replication occurs within viral inclusions, which are specialized nonmembranous cytoplasmic organelles formed by viral nonstructural and structural proteins. Although these structures serve as sites for several major events in the reovirus life cycle, including dsRNA synthesis, gene segment assortment, and genome encapsidation, biochemical mechanisms of virion morphogenesis within inclusions have not been elucidated because much remains unknown about inclusion anatomy and functional organization.

Identification of a second-site suppressor mutation of the GTPase defect associated with McCune-Albright syndrome: a model using the yeast heterotrimeric G protein, GPA1.

McCune-Albright syndrome (MAS) causes a variety of bone and endocrine abnormalities due to the post-zygotic mutation of the alpha subunit of the stimulatory G-protein Gsalpha. This mutation causes signal-independent activity of the G-protein in the affected cells. We report the development of a system to study the effects of MAS mutations using Saccharomyces cerevisiae, wherein activation of the yeast G-protein pathway results in growth arrest in a genetically recessive fashion.