Phosphatidylserine vesicles enable efficient en bloc transmission of enteroviruses.

A central paradigm within virology is that each viral particle largely behaves as an independent infectious unit. Here, we demonstrate that clusters of enteroviral particles are packaged within phosphatidylserine (PS) lipid-enriched vesicles that are non-lytically released from cells and provide greater infection efficiency than free single viral particles. We show that vesicular PS lipids are co-factors to the relevant enterovirus receptors in mediating subsequent infectivity and transmission, in particular to primary human macrophages.

Picornavirus morphogenesis.

The Picornaviridae represent a large family of small plus-strand RNA viruses that cause a bewildering array of important human and animal diseases. Morphogenesis is the least-understood step in the life cycle of these viruses, and this process is difficult to study because encapsidation is tightly coupled to genome translation and RNA replication. Although the basic steps of assembly have been known for some time, very few details are available about the mechanism and factors that regulate this process.

Production and pathogenicity of hepatitis C virus core gene products.

Hepatitis C virus (HCV) is a major cause of chronic liver diseases, including steatosis, cirrhosis and hepatocellular carcinoma, and its infection is also associated with insulin resistance and type 2 diabetes mellitus. HCV, belonging to the Flaviviridae family, is a small enveloped virus whose positive-stranded RNA genome encoding a polyprotein. The HCV core protein is cleaved first at residue 191 by the host signal peptidase and further cleaved by the host signal peptide peptidase at about residue 177 to generate the mature core protein (a.

An interaction between glutathione and the capsid is required for the morphogenesis of C-cluster enteroviruses.

Glutathione (GSH) is the most abundant cellular thiol playing an essential role in preserving a reduced cellular environment. Cellular GSH levels can be efficiently reduced by the GSH biosynthesis inhibitor, L-buthionine sulfoximine (BSO). The aim of our study was to determine the role of GSH in the growth of two C-cluster enteroviruses, poliovirus type 1 (PV1) and coxsackievirus A20 (CAV20).

A C-terminal, cysteine-rich site in poliovirus 2C(ATPase) is required for morphogenesis.

The morphogenesis of viruses belonging to the genus Enterovirus in the family Picornaviridae is still poorly understood despite decades-long investigations. However, we recently provided evidence that 2C(ATPase) gives specificity to poliovirus encapsidation through an interaction with capsid protein VP3. The polypeptide 2C(ATPase) is a highly conserved non-structural protein of enteroviruses with important roles in RNA replication, encapsidation and uncoating.

Both core and F proteins of hepatitis C virus could enhance cell proliferation in transgenic mice.

The role of the protein encoded by the alternative open reading frame (ARF/F/core+1) of the Hepatitis C virus (HCV) genome in viral pathogenesis remains unknown. The different forms of ARF/F/core+1 protein were labile in cultured cells, a myc-tag fused at the N-terminus of the F protein made it more stable. To determine the role of core and F proteins in HCV pathogenesis, transgenic mice with either protein expression under the control of Albumin promoter were generated.

SARS-CoV nucleocapsid protein interacts with cellular pyruvate kinase protein and inhibits its activity.

The pathogenesis of SARS-CoV remains largely unknown. To study the function of the SARS-CoV nucleocapsid protein, we have conducted a yeast two-hybrid screening experiment to identify cellular proteins that may interact with the SARS-CoV nucleocapsid protein. Pyruvate kinase (liver) was found to interact with SARS-CoV nucleocapsid protein in this experiment.

Adenovirus structural protein IIIa is involved in the serotype specificity of viral DNA packaging.

The packaging of the adenovirus (Ad) genome into a capsid displays serotype specificity. This specificity has been attributed to viral packaging proteins, the IVa2 protein and the L1-52/55K protein. We previously found that the Ad17 L1-52/55K protein was not able to complement the growth of an Ad5 L1-52/55K mutant virus, whereas two other Ad17 packaging proteins, IVa2 and L4-22K, could complement the growth of Ad5 viruses with mutations in the respective genes.

Expression and membrane integration of SARS-CoV E protein and its interaction with M protein.

The severe acute respiratory syndrome (SARS)-CoV E gene fragment was cloned and expressed as a recombinant protein fused with a myc tag at the N-terminus in vitro and in Vero E6 cells. Similar to other N-glycosylated proteins, the glycosylation of SARS-CoV E protein occurred co-translationally in the presence of microsomes. The SARS-CoV E protein is predicted to be a double-spanning membrane protein lacking a conventional signal peptide.

Expression and membrane integration of SARS-CoV M protein.

SARS-CoV M gene fragment was cloned and expressed as a recombinant protein fused with a V5 tag at the C-terminus in Vero E6 cells. In addition to un-glycosylated and glycosylated proteins, one product with smaller size initiated in-frame from the third Met residues probably through ribosomal re-initiation was also detected. Translation initiated in-frame from the third Met is unusual since the sequence around the first Met of SARS-CoV M protein contains the optimal consensus Kozak sequence.

Hepatitis C virus ARFP/F protein interacts with cellular MM-1 protein and enhances the gene trans-activation activity of c-Myc.

The ARFP/F protein is synthesized from the +1 reading frame of the hepatitis C virus (HCV) core protein gene. The function of this protein remains unknown. To study the function of the HCV ARFP/F protein, we have conducted the yeast two-hybrid screening experiment to identify cellular proteins that may interact with the ARFP/F protein.

Characterization of the cleavage of signal peptide at the C-terminus of hepatitis C virus core protein by signal peptide peptidase.

Production of hepatitis C virus (HCV) core protein requires the cleavages of polyprotein by signal peptidase and signal peptide peptidase (SPP). Cleavage of signal peptide at the C-terminus of HCV core protein by SPP was characterized in this study. The spko mutant (mutate a.

Thermal aggregation of SARS-CoV membrane protein.

SARS-CoV membrane protein could be detected easily using Western blotting in non-denaturing condition but not regular denaturing treatment. Boiling treatment, causing the aggregation of SARS-CoV membrane protein in the stacking gels, results in the failure to detect the membrane protein in the separating gels. Aggregated membrane proteins could not be dissociated by 1% Triton-X 100, 6M urea, or 2% SDS.

Detection of serologic responses to GB virus C/hepatitis G virus infection.

Objectives: To investigate the prevalence of GB virus C/hepatitis G virus (GBV-C/HGV) and compare the serologic responses to various GBV-C/HGV markers in eastern Taiwan aborigines.

Methods: We used RT-PCR and anti-HGenv u-plate to investigate the prevalence of GBV-C/HGV in eastern Taiwan aborigines. We also used ELISA, dot blot assay, and Western blot to detect the serologic responses to various GBV-C/HGV markers.

The first hydrophobic domain of the hepatitis C virus E1 protein is important for interaction with the capsid protein.

The interaction between the hepatitis C virus capsid protein and the envelope protein E1 has been demonstrated previously in vivo. To determine the binding region of the E1 protein with the capsid protein, this interaction was characterized in vitro. This study shows that the interaction between these proteins should occur in the endoplasmic reticulum membrane rather than in the cytosol and that the first hydrophobic domain of the E1 protein (aa 261-291) is important for the interaction with the capsid protein.