Publications by authors named "Kang Rok Han"

Zika virus (ZIKV), a mosquito-borne flavivirus that has recently emerged globally, poses a major threat to public health. To control this emerging disease, accurate diagnostics are required for monitoring current ZIKV outbreaks. Owing to the high nucleotide sequence similarity and cross-reactivity of ZIKV with other members of the Flaviviridae family, discrimination from other flavivirus infections is often difficult in endemic areas.

View Article and Find Full Text PDF

Modulation of RNA structure is essential in the life cycle of RNA viruses. Immediate replication upon infection requires RNA unwinding to ensure that RNA templates are not in intra- or intermolecular duplex forms. The calicivirus NS3, one of the highly conserved nonstructural (NS) proteins, has conserved motifs common to helicase superfamily 3 among six genogroups.

View Article and Find Full Text PDF

Until recently, molecular studies on human norovirus (HuNoV), a major causative agent of gastroenteritis, have been hampered by the lack of an efficient cell culture system. Murine norovirus-1 (MNV-1) has served as a surrogate model system for norovirus research, due to the availability of robust cell culture systems and reverse genetics. To identify amino acids involved in RNA synthesis by the viral RNA-dependent RNA polymerase (NS7), we constructed NS7 mutants in which basic amino acids surrounding the catalytic site were substituted with alanine.

View Article and Find Full Text PDF

Background: Although the World Health Organization has declared the eradication of smallpox in 1980, the fear of its potential use in bioterrorism has become a reality. Since the effectiveness of current vaccines and antiviral drugs is limited, development of new therapeutic strategies is needed. In this study, we investigated small interfering RNA (siRNA) as a therapeutic approach for preventing and treating smallpox infection.

View Article and Find Full Text PDF

Norovirus, a member of the Caliciviridae family, is a major causative agent of gastroenteritis worldwide. The cDNA of the entire genome of human norovirus (HuNV) was cloned using the RNA extracted from the stool sample of a Korean patient. The RNA genome consists of 7,559 nucleotides, carries 3 open reading frames (ORFs), 5 and 3 noncoding regions, and a poly(A) tail at the 3 end.

View Article and Find Full Text PDF

Murine norovirus-1 (MNV-1) shares many features with human norovirus (HuNoV) and both are classified within the norovirus genus of Caliciviridae family. MNV-1 is used as the surrogate for HuNoV research since it is the only form that can be grown in cell culture. HuNoV and MNV-1 RNA dependent RNA polymerase (RdRp) proteins with the sequence identity of 59% show essentially identical conformations.

View Article and Find Full Text PDF

Norovirus is one of the leading agents of gastroenteritis and is a major public health concern. In this study, the crystal structures of recombinant RNA-dependent RNA polymerase (RdRp) from murine norovirus-1 (MNV-1) and its complex with 5-fluorouracil (5FU) were determined at 2.5 Å resolution.

View Article and Find Full Text PDF

We investigated the roles and biochemical properties of recombinant murine norovirus-1 (MNV-1) 3D(pol) in RNA synthesis and virus genome-linked protein (VPg) nucleotidylylation. We therefore expressed VPg and 3D(pol) of MNV-1 in Escherichia coli. MNV-1 3D(pol) exhibited RNA-dependent RNA polymerase (RdRp) activity in vitro with poly(A) RNA as a template and MnCl(2) as a cofactor.

View Article and Find Full Text PDF